Photo by Taylor Vick (Unsplash)

Linux networking can be confusing due to the wide range of technology stacks and tools in use, in addition to the complexity of the surrounding network environment. The configuration of bridges, bonds, VRFs or routes can be done programmatically, declaratively, manually or with automated with tools like ifupdown, ifupdown2, ifupdown-ng, iproute2, NetworkManager, systemd-networkd and others. Each of these tools use different formats and locations to store their configuration files. Netplan, a utility for easily configuring networking on a Linux system, is designed to unify and standardise how administrators interact with these underlying technologies. Starting from a YAML description of the required network interfaces and what each should be configured to do, Netplan will generate all the necessary configuration for your chosen tool. In this article, we will provide an overview of how Ubuntu uses Netplan to manage Linux networking in a unified way. By creating a common interface across two disparate technology stacks, IT administrators benefit from a unified experience across both desktops and servers whilst retaining the unique advantages of the underlying tech. But first, let s start with a bit of history and show where we are today.

The history of Netplan in Ubuntu Starting with Ubuntu 16.10 and driven by the need to express network configuration in a common way across cloud metadata and other installer systems, we had the opportunity to switch to a network stack that integrates better with our dependency-based boot model. We chose systemd-networkd on server installations for its active upstream community and because it was already part of Systemd and therefore included in any Ubuntu base installation. It has a much better outlook for the future, using modern development techniques, good test coverage and CI integration, compared to the ifupdown tool we used previously. On desktop installations, we kept using NetworkManager due to its very good integration with the user interface. Having to manage and configure two separate network stacks, depending on the Ubuntu variant in use, can be confusing, and we wanted to provide a streamlined user experience across any flavour of Ubuntu. Therefore, we introduced Netplan.io as a control layer above systemd-networkd and NetworkManager. Netplan takes declarative YAML files from /etc/netplan/ as an input and generates corresponding network configuration for the relevant network stack backend in /run/systemd/network/ or /run/NetworkManager/ depending on the system configuration. All while keeping full flexibility to control the underlying network stack in its native way if need be.

Design overview (netplan.io)

Who is using Netplan? Recent versions of Netplan are available and ready to be installed on many distributions, such as Ubuntu, Fedora, RedHat Enterprise Linux, Debian and Arch Linux.

Ubuntu As stated above, Netplan has been installed by default on Ubuntu systems since 2016 and is therefore being used by millions of users across multiple long-term support versions of Ubuntu (18.04, 20.04, 22.04) on a day-to-day basis. This covers Ubuntu server scenarios primarily, such as bridges, bonding, VLANs, VXLANs, VRFs, IP tunnels or WireGuard tunnels, using systemd-networkd as the backend renderer. On Ubuntu desktop systems, Netplan can be used manually through its declarative YAML configuration files, and it will handle those to configure the NetworkManager stack. Keep reading to get a glimpse of how this will be improved through automation and integration with the desktop stack in the future.

Cloud It might not be as obvious, but many people have been using Netplan without knowing about it when configuring a public cloud instance on AWS, Google Cloud or elsewhere through cloud-init. This is because cloud-init s Networking Config Version 2 is a passthrough configuration to Netplan, which will then set up the underlying network stack on the given cloud instance. This is why Netplan is also a key package on the Debian distribution, for example, as it s being used by default on Debian cloud images, too.

Our vision for Linux networking We know that Linux networking can be a beast, and we want to keep simple things simple. But also allow for custom setups of any complexity. With Netplan, the day-to-day networking needs are covered through easily comprehensible and nicely documented YAML files, that describe the desired state of the local network interfaces, which will be rendered into corresponding configuration files for the relevant network stack and applied at (re-)boot or at runtime, using the netplan apply CLI. For example /etc/netplan/lan.yaml:

network:
  version: 2
  renderer: networkd
  ethernets:
    enp3s0:
      dhcp4: true

Having a single source of truth for network configuration is also important for administrators, so they do not need to understand multiple network stacks, but can rely on the declarative data given in /etc/netplan/ to configure a system, independent of the underlying network configuration backend. This is also very helpful to seed the initial network configuration for new Linux installations, for example through installation systems such as Subiquity, Ubuntu s desktop installer or cloud-init across the public and private clouds. In addition to describing and applying network configuration, the netplan status CLI can be used to query relevant data from the underlying network stack(s), such as systemd-networkd, NetworkManager or iproute2, and present them in a unified way.

Netplan status (Debian)

At the Netplan project we strive for very high test automation and coverage with plenty of unit tests, integration tests and linting steps, across multiple Linux distros, which gives high confidence in also supporting more advanced networking use cases, such as Open vSwitch or SR-IOV network virtualization, in addition to normal wired (static IP, DHCP, routing), wireless (e.g. wwan modems, WPA2/3 connections, WiFi hotspot, controlling the regulatory domain, ) and common server scenarios. Should there ever be a scenario that is not covered by Netplan natively, it allows for full flexibility to control the underlying network stack directly through systemd override configurations or NetworkManager passthrough settings in addition to having manual configuration side-by-side with interfaces controlled through Netplan.

The future of Netplan desktop integration On workstations, the most common scenario is for end users to configure NetworkManager through its user interface tools, instead of driving it through Netplan s declarative YAML files, which makes use of NetworkManager s native configuration files. To avoid Netplan just handing over control to NetworkManager on such systems, we re working on a bidirectional integration between NetworkManager and Netplan to further improve the single source of truth use case on Ubuntu desktop installations. Netplan is shipping a libnetplan library that provides an API to access Netplan s parser and validation internals, that can be used by NetworkManager to write back a network interface configuration. For instance, configuration given through NetworkManager s UI tools or D-Bus API can be exported to Netplan s native YAML format in the common location at /etc/netplan/. This way, administrators just need to care about Netplan when managing a fleet of Desktop installations. This solution is currently being used in more confined environments, like Ubuntu Core, when using the NetworkManager snap, and we will deliver it to generic Ubuntu desktop systems in 24.04 LTS. In addition to NetworkManager, libnetplan can also be used to integrate with other tools in the networking space, such as cloud-init for improved validation of user data or installation systems when seeding new Linux images.

Conclusion Overall, Netplan can be considered to be a good citizen within a network environment that plays hand-in-hand with other networking tools and makes it easy to control modern network stacks, such as systemd-networkd or NetworkManager in a common, streamlined and declarative way. It provides a single source of truth to network administrators about the network state, while keeping simple things simple, but allowing for arbitrarily complex custom setups.
If you want to learn more, feel free to follow our activities on Netplan.io, GitHub, Launchpad, IRC or our Netplan Developer Diaries blog on discourse.

I m six months into my journey of building a business which means its time to reflect and review the goals I set for the year.

No further investment in co2mon.nz In March I made the decision to focus on completing the market research for co2mon.nz. The results of that research led to two key conclusions:

1. Indoor air quality/ventilation is not a problem many people are actively thinking about or looking to spend money to improve.
2. Even when introduced to the problem and educated about the need, most people are looking for a one-off expense or solution (e.g. the physical monitor) and are much less interested in a monitoring software service.

Based on that, it was clear that this is not an opportunity that I should continue pursuing and I ve put co2mon.nz into maintenance mode. I ve committed to maintaining the infrastructure to support existing customers, but I won t be investing time or energy in developing it further.

Discipline in selecting product opportunities The decision to stop investing more time into co2mon.nz was straightforward given the results of the research, but it was also painful given the time I ve already sunk into it. I hindsight it s clear that my enthusiasm to solve a problem with technology I enjoyed was my driving force rather than a deep understanding of the wants and needs of potential customers. I don t entirely regret trying my luck once - but it s not time efficient and I know that following that pattern again is not a sustainable or viable path to building a successful business. I ve decided to use the following list of questions to bring more discipline to how I evaluate product opportunities in future:

1. Problem: Is this something that a sizeable number of people are struggling with AND are willing to spend money solving?
   • I find the framework from Excuse me, is there a problem? really useful in thinking about this question.
2. Capability: Can I deliver a solution that solves the problem in a reliable and cost-effective way?
3. Excitement: Am I excited and motivated to invest time in building the solution to this problem?
4. Trust: Do I have the expertise and experience to be trusted to solve the problem by potential customers?
5. Execution: Can I package, market and sell that solution in a profitable manner?

My plan is to answer these questions and then make an evaluation of the potential before I commit time to building any part of a product. As an example of how I think that will help, here s what I think the answer to those questions for ventilation monitoring would have been:

1. Problem: No - as the market research eventually showed.
2. Capability: Low - The part of the solution which customers primarily value (the hardware) is complex and outside of my core experience. The software I can easily deliver is not where the value is seen.
3. Excitement: Yes - this was the primary driver of starting the project.
4. Trust: Low - I m trusted to build software, but cannot claim any specific expertise in air quality and ventilation.
5. Execution: Low confidence - These skills are not ones I ve exercised a lot in my career to date.

What these answers point to is that identifying the problem alone is not enough. I don t expect every question to have a perfect answer, but I want to hold myself to only pursuing opportunities where there s only one major area of doubt. In this case, even had the market research demonstrated a problem that many customers would pay to solve, there were still some big answers missing to the trust, capability and execution questions. Overall my conclusion is that co2mon.nz was not the ideal business to start my journey with given the number of open questions in the plan. I like to think that conclusion would also have been clear to me six months ago had I taken the time to go through this process then!

Prioritising areas of growth Applying those questions to my other product ideas results in a lot of I don t know yet answers to the problem and capability questions, further reinforcing the lesson that I need to spend more understanding if there is a problem with a viable business model attached in those areas before progressing any of those ideas. Beyond that lesson, a more interesting observation comes from the last question regarding execution. My answers to the first four questions vary between ideas, but my answers to this last question are always the same - I don t have a lot of confidence in my sales and marketing skills to sell a product. That s not a surprise. My career to date has been focused on software development and leadership, I don t have a lot of experience with sales and marketing. The opportunity to grow and develop those skills is actually a large part of my motivation for choosing the path of building my own business. But seeing that this is a common factor that will need significant investment regardless of which opportunity I pursue sends me a strong signal that I should focus on growth in this area as a priority. Following that logic through to the next step of what creating that focus would look like reveals a conflict: The nature of the mission I ve set for myself draws me to products in areas that are new to me, which means there s also a need to invest in building expertise in those areas. Again not a surprise, but the time and focus required to develop that expertise competes with time spent growing my sales and marketing skills. So I have a prioritisation problem. Solving it is going to require changing the type of product I m trying to build in the short term: I need to build a product that uses my existing expertise and strengths as much as possible, so that I can put the majority of my energy into growing the core business skills where my confidence is currently lacking. Trying to deliver meaningful improvements to a big problem in an area I don t have past experience in while also learning how to sell and market a product is biting off more than I chew right away.

Changing the goal posts With those lessons in hand I m making three changes to my 2023 Goals:

1. Reducing the product development goal from several ideas to two. The first was co2mon.nz. The second will be drawn from my existing expertise - not one of the previously stated ideas that require me to develop expertise in a new area.
2. Moving the consulting and product development goals to be alternatives - I expect I can achieve at most one of them this year.
3. Reducing the publishing target for this site from at least once a week to once a month . I thought I d have more to say this year, but the words are coming very slowly to me.

Reducing scope and ambition is humbling, but that s reality. I hope it turns out to be a case of slow down and lay the foundations in order to then move faster. The good news is that I don t feel the need to make any changes to the vision, mission and strategy I m following - I think they re still the right destination and overall path for me even though the first six months has proven bumpy. I just need to be a bit more realistic on the short-term goals that will feed into them.

The next few months I m choosing to prioritise the product development goal. I m aiming to complete the market research/problem definition phase for a product opportunity I ve identified in the SRE/DevOps space (where my previous experience is) and make a decision on whether to start development by mid August. In making that decision I plan to gather the answers to my questions, and then diligently evaluate whether the opportunity is worth committing to or not. I will write more about this process in coming weeks. If I decide to proceed that gives me 2-3 months to get an MVP in the hands of customers and get concrete validation of whether the product has revenue and growth potential before the end of the year. Tight, but if things go well, and I don t take any further consulting work, there s a reasonable chance I can complete the revised goal successfully. In the event that I decide the product opportunity I m currently researching is not the right one to commit to, I will likely revert to focusing on my consulting goal in the remaining 2-3 months of the year rather than attempt a third product development iteration. Thanks for reading this far! As always, I d love your thoughts and feedback.

Appendix: Revised 2023 Goals Putting all that together, the ultimate outcome of this review (including updated progress scoring) looks like:

1. Execute a series of successful consulting engagements, building a reputation for myself and leaving happy customers willing to provide testimonials that support a pipeline of future opportunities. Score: 3/10 - I focused entirely on co2mon.nz during April, May and June to the detriment of my pipeline of consulting work. This score is unlikely to improve given the above plan unless I decide not to commit to developing the idea I m currently investigating.
2. Grow my product development skill set by taking two ideas (co2mon.nz, an SRE/DevOps focused product) to MVP stage with customer feedback received, and generate revenue and has growth potential from one of them. Score: 4/10 - I launched co2mon.nz and got feedback, I discovered it didn t solve a problem relevant to customers and therefore did not generate substantial revenue or growth potential. Idea number two is in still in progress.
3. Develop and maintain a broad professional network.
   1. To build a professional relationship with at least 30 new people this year. Score: 6/10 - This is going well. On track for a 10/10 score.
   2. To publish a piece of writing on this site once a month and for many of those to generate interesting conversations and feedback. Score: 6/10 - 4 out of 6 months have featured a post meeting this goal so far.
   3. To support the growth of my local technical community by volunteering my experience and knowledge with others. Score: 5/10 - I ve given one talk and helped with SREcon23 APAC, but not as much other work in this area as I d like.

This is the fourth in a series about archiving to removable media (optical discs such as BD-Rs and DVD+Rs or portable hard drives). Here are the first three parts:

• In part 1, I laid out my goals for the project, and considered a number of tools before determining dar and git-annex were my leading options.
• In part 2, I took a deep dive into git-annex and simulated using it for this project.
• In part 3, I did the same with dar.
• And in this part, I want to put it together to come up with an initial direction to pursue.

I want to state at the outset that this is not a general review of dar or git-annex. This is an analysis of how those tools stack up to a particular use case. Neither tool focuses on this use case, and I note it is particularly far from the more common uses of git-annex. For instance, both tools offer support for cloud storage providers and special support for ssh targets, but neither of those are in-scope for this post. Comparison Matrix As part of this project, I made a comparison matrix which includes not just dar and git-annex, but also backuppc, bacula/bareos, and borg. This may give you some good context, and also some reference for other projects in this general space. Reviewing the Goals I identified some goals in part 1. They are all valid. As I have thought through the project more, I feel like I should condense them into a simpler ordered list, with the first being the most important. I omit some things here that both dar and git-annex can do (updates/incrementals, for instance; see the expanded goals list in part 1). Here they are:

1. The tool must not modify the source data in any way.
2. It must be simple to create or update an archive. Processes that require a lot of manual work, are flaky, or are difficult to do correctly, are unlikely to be done correctly and often. If it s easy to do right, I m more likely to do it. Put another way: an archive never created can never be restored.
3. The chances of a successful restore by someone that is not me, that doesn t know Linux, and is at least 10 years in the future, should be maximized. This implies a simple toolset, solid support for dealing with media errors or missing media, etc.
4. Both a partial point-in-time restore and a full restore should be possible. The full restore must, at minimum, provide a consistent directory tree; that is, deletions, additions, and moves over time must be accurately reflected. Preserving modification times is a near-requirement, and preserving hard links, symbolic links, and other POSIX metadata is a significant nice-to-have.
5. There must be a strategy to provide redundancy; for instance, a way for one set of archive discs to be offsite, another onsite, and the two to be periodically swapped.
6. Use storage space efficiently.

Let s take a look at how the two stack up against these goals. Goal 1: Not modifying source data With dar, this is accomplished. dar --create does not modify source data (and even has a mode to avoid updating atime) so that s done. git-annex normally does modify source data, in that it typically replaces files with symlinks into its hash-indexed storage directory. It can instead use hardlinks. In either case, you will wind up with files that have identical content (but may have originally been separate, non-linked files) linked together with git-annex. This would cause me trouble, as well as run the risk of modifying timestamps. So instead of just storing my data under a git-annex repo as is its most common case, I use the directory special remote with importtree=yes to sort of import the data in. This, plus my desire to have the repos sensible and usable on non-POSIX operating systems, accounts for a chunk of the git-annex complexity you see here. You wouldn t normally see as much complexity with git-annex (though, as you will see, even without the directory special remote, dar still has less complexity). Winner: dar, though I demonstrated a working approach with git-annex as well. Goal 2: Simplicity of creating or updating an archive Let us simply start by recognizing this:

• Number of commands to create a first dar archive, including all splits: 1
• Number of commands to create a first git-annex archive, with just the first two splits: 58
• Number of commands to create a dar incremental: 1
• Number of commands to update the last git-annex drive: 10
• Number of commands to do a full restore of all slices and both archives with dar: 2 (1 if dar_manager used)
• Number of commands to do a full restore of just the first two drive with git-annex: 9 (but my process may not be correct)

Both tools have a lot of power, but I must say, it is easier to wrap my head around what dar is doing than what git-annex is doing. Everything dar does is with files: here are the files to archive, here is an archive file, here is a detached (isolated) catalog. It is very straightforward. It took me far less time to develop my dar page than my git-annex page, despite having existing familiarity with both tools. As I pointed out in part 2, I still don t fully understand how git-annex syncs metadata. Unsolved mysteries from that post include why the two git-annex drives had no idea what was on the other drives, and why the export operation silenty did nothing. Additionally, for the optical disc case, I had to create a restricted-size filesystem/dataset for git-annex to write into in order to get the desired size limit. Looking at the optical disc case, dar has a lot of nice infrastructure built in. With pause and execute, it can very easily be combined with disc burning operations. slice will automatically limit the size of a given slice, regardless of how much disk space is free, meaning that the git-annex tricks of creating smaller filesystems/datasets are unnecessary with dar. To create an initial full backup with dar, you just give it the size of the device, and it will automatically split up the archive, with hooks to integrate for burning or changing drives. About as easy as you could get. With git-annex, you would run the commands to have it fill up the initial filesystem, then burn the disc (or remove the drive), then run the commands to create another repo on the second filesystem, and so forth. With hard drives, with git-annex you would do something similar; let it fill up a repo on a drive, and if it exits with a space error, swap in the next. With dar, you would slice as with an optical disk. Dar s slicing is less convenient in this case, though, as it assumes every drive is the same size and yours may not be. You could work around that by using a slice size no bigger than the smallest drive, and putting multiple slices on larger drives if need be. If a single drive is large enough to hold your entire data set, though, you need not worry about this with either tool. Here s a warning about git-annex: it won t store anything beneath directories named .git. My use case doesn t have many of those. If your use case does, you re going to have to figure out what to do about it. Maybe rename them to something else while the backup runs? In any case, it is simply a fact that git-annex cannot back up git repositories, and this cuts against being able to back up things correctly. Another point is that git-annex has scalability concerns. If your archive set gets into the hundreds of thousands of files, you may need to split it into multiple distinct git-annex repositories. If this occurs and it will in my case it may serve to dull the shine of some of git-annex s features such as location tracking. A detour down the update strategies path Update strategies get a little more complicated with both. First, let s consider: what exactly should our update strategy be? For optical discs, I might consider doing a monthly update. I could burn a disc (or more than one, if needed) regardless of how much data is going to go onto it, because I want no more than a month s data lost in any case. An alternative might be to spool up data until I have a disc s worth, and then write that, but that could possibly mean months between actually burning a disc. Probably not good. For removable drives, we re unlikely to use a new drive each month. So there it makes sense to continue writing to the drive until it s full. Now we have a choice: do we write and preserve each month s updates, or do we eliminate intermediate changes and just keep the most recent data? With both tools, the monthly burn of an optical disc turns out to be very similar to the initial full backup to optical disc. The considerations for spanning multiple discs are the same. With both tools, we would presumably want to keep some metadata on the host so that we don t have to refer to a previous disc to know what was burned. In the dar case, that would be an isolated catalog. For git-annex, it would be a metadata-only repo. I illustrated both of these in parts 2 and 3. Now, for hard drives. Assuming we want to continue preserving each month s updates, with dar, we could just write an incremental to the drive each month. Assuming that the size of the incremental is likely far smaller than the size of the drive, you could easily enough do this. More fancily, you could look at the free space on the drive and tell dar to use that as the size of the first slice. For git-annex, you simply avoid calling drop/dropunused. This will cause the old versions of files to accumulate in .git/annex. You can get at them with git annex commands. This may imply some degree of elevated risk, as you are modifying metadata in the repo each month, which with dar you could chmod a-w or even chattr +i the archive files once written. Hopefully this elevated risk is low. If you don t want to preserve each month s updates, with dar, you could just write an incremental each month that is based on the previous drive s last backup, overwriting the previous. That implies some risk of drive failure during the time the overwrite is happening. Alternatively, you could write an incremental and then use dar to merge it into the previous incremental, creating a new one. This implies some degree of extra space needed (maybe on a different filesystem) while doing this. With git-annex, you would use drop/dropunused as I demonstrated in part 2. The winner for goal 2 is dar. The gap is biggest with optical discs and more narrow with hard drives, thanks to git-annex s different options for updates. Still, I would be more confident I got it right with dar. Goal 3: Greatest chance of successful restore in the distant future If you use git-annex like I suggested in part 2, you will have a set of discs or drives that contain a folder structure with plain files in them. These files can be opened without any additional tools at all. For sheer ability to get at raw data, git-annex has the edge. When you talk about getting a consistent full restore without multiple copies of renamed files or deleted files coming back then you are going to need to use git-annex to do that. Both git-annex and dar provide binaries. Dar provides a win64 version on its Sourceforge page. On the author s releases site, you can find the win64 version in addition to a statically-linked x86_64 version for Linux. The git-annex install page mostly directs you to package managers for your distribution, but the downloads page also lists builds for Linux, Windows, and Mac OS X. The Linux version is dynamic, but ships most of its .so files alongside. The Windows version requires cygwin.dll, and all versions require you to also install git itself. Both tools are in package managers for Mac OS X, Debian, FreeBSD, and so forth. Let s just say that you are likely to be able to run either one on a future Windows or Linux system. There are also GUI frontends for dar, such as DARGUI and gdar. This can increase the chances of a future person being able to use the software easily. git-annex has the assistant, which is based on a different use case and probably not directly helpful here. When it comes to doing the actual restore process using software, dar provides the easier process here. For dealing with media errors and the like, dar can integrate with par2. While technically you could use par2 against the files git-annex writes, that s more cumbersome to manage to the point that it is likely not to be done. Both tools can deal reasonably with missing media entirely. I m going to give the edge on this one to git-annex; while dar does provide the easier restore and superior tools for recovering from media errors, the ability to access raw data as plain files without any tools at all is quite compelling. I believe it is the most critical advantage git-annex has, and it s a big one. Goal 4: Support high-fidelity partial and full restores Both tools make it possible to do a full restore reflecting deletions, additions, and so forth. Dar, as noted, is easier for this, but it is possible with git-annex. So, both can achieve a consistent restore. Part of this goal deals with fidelity of the restore: preserving timestamps, hard and symbolic links, ownership, permissions, etc. Of these, timestamps are the most important for me. git-annex can t do any of that. dar does all of it. Some of this can be worked around using mtree as I documented in part 2. However, that implies a need to also provide mtree on the discs for future users, and I m not sure mtree really exists for Windows. It also cuts against the argument that git-annex discs can be used without any tools. It is true, they can, but all you will get is filename and content; no accurate date. Timestamps are often highly relevant for everything from photos to finding an elusive document or record. Winner: dar. Goal 5: Supporting backup strategies with redundancy My main goal here is to have two separate backup sets: one that is offsite, and one that is onsite. Depending on the strategy and media, they might just always stay that way, or periodically rotate. For instance, with optical discs, you might just burn two copies of every disc and store one at each place. For hard drives, since you will be updating the content of them, you might swap them periodically. This is possible with both tools. With both tools, if using the optical disc scheme I laid out, you can just burn two identical copies of each disc. With the hard drive case, with dar, you can keep two directories of isolated catalogs, one for each drive set. A little identifier file on each drive will let you know which set to use. git-annex can track locations itself. As I demonstrated in part 2, you can make each drive its own repo, add all drives from a given drive set to a git-annex group. When initializing a drive, you tell git-annex what group it s a prt of. From then on, git-annex knows what content is in each group and will add whatever a given drive s group needs to that drive. It s possible to do this with both, but the winner here is git-annex. Goal 6: Efficient use of storage Here are situations in which one or the other will be more efficient:

• Lots of small files: dar, due to reduced filesystem overhead
• Compressible data: dar (git-annex doesn t support compression)
• Renamed files: git-annex (it will detect the sha256 match and avoid storing a duplicate copy)
• Identical files: git-annex, unless they are hardlinked already (again, detects the sha256 match)
• Small modifications to files (eg, ID3 tags on MP3s, EXIF data on photos, etc): dar (it supports rsync-style binary deltas)

The winner depends on your particular situation. Other notes While not part of the goals above, dar is capable of using tapes directly. While not as common, they are often used in communities of people that archive lots of data. Conclusions Overall, dar is the winner for me. It is simpler in most areas, easier to get correct, and scales very well. git-annex does, however, have some quite compelling points. Being able to access files as plain files is huge, and its location tracking is nicer than dar s, even when using dar_manager. Both tools are excellent and I recommend them both and for more than the particular scenario shown here. Both have fantastic and responsive authors.

Contributing to Debian is part of Freexian s mission. This article covers the latest achievements of Freexian and their collaborators. All of this is made possible by organizations subscribing to our Long Term Support contracts and consulting services.

/usr-merge, by Helmut Grohne, et al The work on /usr-merge continues from May. The lengthy discussion was condensed into a still lengthy rewrite of DEP17 listing all known problems and proposed mitigations. An initial consensus call did not resolve all questions, but we now have rough consensus on finalizing the transition without relying on major changes to dpkg. Other questions still have diverging opinions and some matters such as how to not break backports are still missing satisfying answers.

DebConf Bursary prep, by Utkarsh Gupta DebCamp and DebConf is happening from 03rd September to 17th September in Kochi, India, and the DebConf Bursary team is gearing up for that. After extending the bursary deadline (catering to the requests coming in from various people), we ve finally managed to clock over 260 bursary requests. The team is set up and we re starting to review the applications. The team intends to roll out the result as soon as possible.

debci, by Helmut Grohne As Freexian is working on deploying autopkgtests for the LTS and ELTS services, debci and autopkgtests were improved in Debian to better deal with derivatives (e.g. by better supporting external package signing keyrings). Other aspects that are not deployed on ci.debian.net such as the qemu backend were also improved. We express thanks to the relevant maintainers Antonio Terceiro, Paul Gevers and Simon McVittie for their timely reviews and merges of our changes.

Miscellaneous contributions

• Following the release of Debian 12, Rapha l Hertzog updated tracker.debian.org to be aware of trixie. He also pushed some fixes to distro-tracker (the software powering tracker.debian.org) and released version 1.2.0 (since the former release was lacking fixes to run on Debian 12 bookworm).
• Following the release of Debian 12, Helmut Grohne updated crossqa.debian.net systems. He also sent 7 patches for cross build failures and continued adapting rebootstrap to changes in unstable.
• Santiago Ruano Rinc n started to work on how to improve the robustness of Salsa CI s pipeline for some jobs failing frequently.
• Thorsten Alteholz did security updates of cpdb-libs in Unstable and Bookworm.
• Stefano Rivera upgraded pixelfed.debian.social to bookworm.
• Stefano started an re2 library transition, and started preparation for the next transition.
• Helmut Grohne updated debvm in unstable releasing changes that accumulated during the freeze.
• Stefano did some work on the website and infrastructure for DebConf 23.
• Utkarsh Gupta helped review and fix open redmine bugs and fix them all in unstable.

A personal reflection on how I moved from my Debian home to find two new homes with Trisquel and Guix for my own ethical computing, and while doing so settled my dilemma about further Debian contributions. Debian s contributions to the free software community has been tremendous. Debian was one of the early distributions in the 1990 s that combined the GNU tools (compiler, linker, shell, editor, and a set of Unix tools) with the Linux kernel and published a free software operating system. Back then there were little guidance on how to publish free software binaries, let alone entire operating systems. There was a lack of established community processes and conflict resolution mechanisms, and lack of guiding principles to motivate the work. The community building efforts that came about in parallel with the technical work has resulted in a steady flow of releases over the years. From the work of Richard Stallman and the Free Software Foundation (FSF) during the 1980 s and early 1990 s, there was at the time already an established definition of free software. Inspired by free software definition, and a belief that a social contract helps to build a community and resolve conflicts, Debian s social contract (DSC) with the free software community was published in 1997. The DSC included the Debian Free Software Guidelines (DFSG), which directly led to the Open Source Definition.

One of my earlier Slackware install disk sets, kept for nostalgic reasons.

I was introduced to GNU/Linux through Slackware in the early 1990 s (oh boy those nights calculating XFree86 modeline s and debugging sendmail.cf) and primarily used RedHat Linux during ca 1995-2003. I switched to Debian during the Woody release cycles, when the original RedHat Linux was abandoned and Fedora launched. It was Debian s explicit community processes and infrastructure that attracted me. The slow nature of community processes also kept me using RedHat for so long: centralized and dogmatic decision processes often produce quick and effective outcomes, and in my opinion RedHat Linux was technically better than Debian ca 1995-2003. However the RedHat model was not sustainable, and resulted in the RedHat vs Fedora split. Debian catched up, and reached technical stability once its community processes had been grounded. I started participating in the Debian community around late 2006. My interpretation of Debian s social contract is that Debian should be a distribution of works licensed 100% under a free license. The Debian community has always been inclusive towards non-free software, creating the contrib/non-free section and permitting use of the bug tracker to help resolve issues with non-free works. This is all explained in the social contract. There has always been a clear boundary between free and non-free work, and there has been a commitment that the Debian system itself would be 100% free. The concern that RedHat Linux was not 100% free software was not critical to me at the time: I primarily (and happily) ran GNU tools on Solaris, IRIX, AIX, OS/2, Windows etc. Running GNU tools on RedHat Linux was an improvement, and I hadn t realized it was possible to get rid of all non-free software on my own primary machine. Debian realized that goal for me. I ve been a believer in that model ever since. I can use Solaris, macOS, Android etc knowing that I have the option of using a 100% free Debian. While the inclusive approach towards non-free software invite and deserve criticism (some argue that being inclusive to non-inclusive behavior is a bad idea), I believe that Debian s approach was a successful survival technique: by being inclusive to and a compromise between free and non-free communities, Debian has been able to stay relevant and contribute to both environments. If Debian had not served and contributed to the free community, I believe free software people would have stopped contributing. If Debian had rejected non-free works completely, I don t think the successful Ubuntu distribution would have been based on Debian. I wrote the majority of the text above back in September 2022, intending to post it as a way to argue for my proposal to maintain the status quo within Debian. I didn t post it because I felt I was saying the obvious, and that the obvious do not need to be repeated, and the rest of the post was just me going down memory lane. The Debian project has been a sustainable producer of a 100% free OS up until Debian 11 bullseye. In the resolution on non-free firmware the community decided to leave the model that had resulted in a 100% free Debian for so long. The goal of Debian is no longer to publish a 100% free operating system, instead this was added: The Debian official media may include firmware . Indeed the Debian 12 bookworm release has confirmed that this would not only be an optional possibility. The Debian community could have published a 100% free Debian, in parallel with the non-free Debian, and still be consistent with their newly adopted policy, but chose not to. The result is that Debian s policies are not consistent with their actions. It doesn t make sense to claim that Debian is 100% free when the Debian installer contains non-free software. Actions speaks louder than words, so I m left reading the policies as well-intended prose that is no longer used for guidance, but for the peace of mind for people living in ivory towers. And to attract funding, I suppose. So how to deal with this, on a personal level? I did not have an answer to that back in October 2022 after the vote. It wasn t clear to me that I would ever want to contribute to Debian under the new social contract that promoted non-free software. I went on vacation from any Debian work. Meanwhile Debian 12 bookworm was released, confirming my fears. I kept coming back to this text, and my only take-away was that it would be unethical for me to use Debian on my machines. Letting actions speak for themselves, I switched to PureOS on my main laptop during October, barely noticing any difference since it is based on Debian 11 bullseye. Back in December, I bought a new laptop and tried Trisquel and Guix on it, as they promise a migration path towards ppc64el that PureOS do not. While I pondered how to approach my modest Debian contributions, I set out to learn Trisquel and gained trust in it. I migrated one Debian machine after another to Trisquel, and started to use Guix on others. Migration was easy because Trisquel is based on Ubuntu which is based on Debian. Using Guix has its challenges, but I enjoy its coherant documented environment. All of my essential self-hosted servers (VM hosts, DNS, e-mail, WWW, Nextcloud, CI/CD builders, backup etc) uses Trisquel or Guix now. I ve migrated many GitLab CI/CD rules to use Trisquel instead of Debian, to have a more ethical computing base for software development and deployment. I wish there were official Guix docker images around. Time has passed, and when I now think about any Debian contributions, I m a little less muddled by my disappointment of the exclusion of a 100% free Debian. I realize that today I can use Debian in the same way that I use macOS, Android, RHEL or Ubuntu. And what prevents me from contributing to free software on those platforms? So I will make the occasional Debian contribution again, knowing that it will also indirectly improve Trisquel. To avoid having to install Debian, I need a development environment in Trisquel that allows me to build Debian packages. I have found a recipe for doing this: # System commands:
sudo apt-get install debhelper git-buildpackage debian-archive-keyring
sudo wget -O /usr/share/debootstrap/scripts/debian-common https://sources.debian.org/data/main/d/debootstrap/1.0.128%2Bnmu2/scripts/debian-common
sudo wget -O /usr/share/debootstrap/scripts/sid https://sources.debian.org/data/main/d/debootstrap/1.0.128%2Bnmu2/scripts/sid
# Run once to create build image:
DIST=sid git-pbuilder create --mirror http://deb.debian.org/debian/ --debootstrapopts "--exclude=usr-is-merged" --basepath /var/cache/pbuilder/base-sid.cow
# Run in a directory with debian/ to build a package:
gbp buildpackage --git-pbuilder --git-dist=sid How to sustainably deliver a 100% free software binary distributions seems like an open question, and the challenges are not all that different compared to the 1990 s or early 2000 s. I m hoping Debian will come back to provide a 100% free platform, but my fear is that Debian will compromise even further on the free software ideals rather than the opposite. With similar arguments that were used to add the non-free firmware, Debian could compromise the free software spirit of the Linux boot process (e.g., non-free boot images signed by Debian) and media handling (e.g., web browsers and DRM), as Debian have already done with appstore-like functionality for non-free software (Python pip). To learn about other freedom issues in Debian packaging, browsing Trisquel s helper scripts may enlight you. Debian s setback and the recent setback for RHEL-derived distributions are sad, and it will be a challenge for these communities to find internally consistent coherency going forward. I wish them the best of luck, as Debian and RHEL are important for the wider free software eco-system. Let s see how the community around Trisquel, Guix and the other FSDG-distributions evolve in the future. The situation for free software today appears better than it was years ago regardless of Debian and RHEL s setbacks though, which is important to remember! I don t recall being able install a 100% free OS on a modern laptop and modern server as easily as I am able to do today. Happy Hacking! Addendum 22 July 2023: The original title of this post was Coping with non-free Debian, and there was a thread about it that included feedback on the title. I do agree that my initial title was confrontational, and I ve changed it to the more specific Coping with non-free software in Debian. I do appreciate all the fine free software that goes into Debian, and hope that this will continue and improve, although I have doubts given the opinions expressed by the majority of developers. For the philosophically inclined, it is interesting to think about what it means to say that a compilation of software is freely licensed. At what point does a compilation of software deserve the labels free vs non-free? Windows probably contains some software that is published as free software, let s say Windows is 1% free. Apple authors a lot of free software (as a tangent, Apple probably produce more free software than what Debian as an organization produces), and let s say macOS contains 20% free software. Solaris (or some still maintained derivative like OpenIndiana) is mostly freely licensed these days, isn t it? Let s say it is 80% free. Ubuntu and RHEL pushes that closer to let s say 95% free software. Debian used to be 100% but is now slightly less at maybe 99%. Trisquel and Guix are at 100%. At what point is it reasonable to call a compilation free? Does Debian deserve to be called freely licensed? Does macOS? Is it even possible to use these labels for compilations in any meaningful way? All numbers just taken from thin air. It isn t even clear how this can be measured (binary bytes? lines of code? CPU cycles? etc). The caveat about license review mistakes applies. I ignore Debian s own claims that Debian is 100% free software, which I believe is inconsistent and no longer true under any reasonable objective analysis. It was not true before the firmware vote since Debian ships with non-free blobs in the Linux kernel for example.

The phrase "Root of Trust" turns up at various points in discussions about verified boot and measured boot, and to a first approximation nobody is able to give you a coherent explanation of what it means[1]. The Trusted Computing Group has a fairly wordy definition, but (a) it's a lot of words and (b) I don't like it, so instead I'm going to start by defining a root of trust as "A thing that has to be trustworthy for anything else on your computer to be trustworthy".

(An aside: when I say "trustworthy", it is very easy to interpret this in a cynical manner and assume that "trust" means "trusted by someone I do not necessarily trust to act in my best interest". I want to be absolutely clear that when I say "trustworthy" I mean "trusted by the owner of the computer", and that as far as I'm concerned selling devices that do not allow the owner to define what's trusted is an extremely bad thing in the general case)

Let's take an example. In verified boot, a cryptographic signature of a component is verified before it's allowed to boot. A straightforward implementation of a verified boot implementation has the firmware verify the signature on the bootloader or kernel before executing it. In this scenario, the firmware is the root of trust - it's the first thing that makes a determination about whether something should be allowed to run or not[2]. As long as the firmware behaves correctly, and as long as there aren't any vulnerabilities in our boot chain, we know that we booted an OS that was signed with a key we trust.

But what guarantees that the firmware behaves correctly? What if someone replaces our firmware with firmware that trusts different keys, or hot-patches the OS as it's booting it? We can't just ask the firmware whether it's trustworthy - trustworthy firmware will say yes, but the thing about malicious firmware is that it can just lie to us (either directly, or by modifying the OS components it boots to lie instead). This is probably not sufficiently trustworthy!

Ok, so let's have the firmware be verified before it's executed. On Intel this is "Boot Guard", on AMD this is "Platform Secure Boot", everywhere else it's just "Secure Boot". Code on the CPU (either in ROM or signed with a key controlled by the CPU vendor) verifies the firmware[3] before executing it. Now the CPU itself is the root of trust, and, well, that seems reasonable - we have to place trust in the CPU, otherwise we can't actually do computing. We can now say with a reasonable degree of confidence (again, in the absence of vulnerabilities) that we booted an OS that we trusted. Hurrah!

Except. How do we know that the CPU actually did that verification? CPUs are generally manufactured without verification being enabled - different system vendors use different signing keys, so those keys can't be installed in the CPU at CPU manufacture time, and vendors need to do code development without signing everything so you can't require that keys be installed before a CPU will work. So, out of the box, a new CPU will boot anything without doing verification[4], and development units will frequently have no verification.

As a device owner, how do you tell whether or not your CPU has this verification enabled? Well, you could ask the CPU, but if you're doing that on a device that booted a compromised OS then maybe it's just hotpatching your OS so when you do that you just get RET_TRUST_ME_BRO even if the CPU is desperately waving its arms around trying to warn you it's a trap. This is, unfortunately, a problem that's basically impossible to solve using verified boot alone - if any component in the chain fails to enforce verification, the trust you're placing in the chain is misplaced and you are going to have a bad day.

So how do we solve it? The answer is that we can't simply ask the OS, we need a mechanism to query the root of trust itself. There's a few ways to do that, but fundamentally they depend on the ability of the root of trust to provide proof of what happened. This requires that the root of trust be able to sign (or cause to be signed) an "attestation" of the system state, a cryptographically verifiable representation of the security-critical configuration and code. The most common form of this is called "measured boot" or "trusted boot", and involves generating a "measurement" of each boot component or configuration (generally a cryptographic hash of it), and storing that measurement somewhere. The important thing is that it must not be possible for the running OS (or any pre-OS component) to arbitrarily modify these measurements, since otherwise a compromised environment could simply go back and rewrite history. One frequently used solution to this is to segregate the storage of the measurements (and the attestation of them) into a separate hardware component that can't be directly manipulated by the OS, such as a Trusted Platform Module. Each part of the boot chain measures relevant security configuration and the next component before executing it and sends that measurement to the TPM, and later the TPM can provide a signed attestation of the measurements it was given. So, an SoC that implements verified boot should create a measurement telling us whether verification is enabled - and, critically, should also create a measurement if it isn't. This is important because failing to measure the disabled state leaves us with the same problem as before; someone can replace the mutable firmware code with code that creates a fake measurement asserting that verified boot was enabled, and if we trust that we're going to have a bad time.

(Of course, simply measuring the fact that verified boot was enabled isn't enough - what if someone replaces the CPU with one that has verified boot enabled, but trusts keys under their control? We also need to measure the keys that were used in order to ensure that the device trusted only the keys we expected, otherwise again we're going to have a bad time)

So, an effective root of trust needs to:

1) Create a measurement of its verified boot policy before running any mutable code
2) Include the trusted signing key in that measurement
3) Actually perform that verification before executing any mutable code

and from then on we're in the hands of the verified code actually being trustworthy, and it's probably written in C so that's almost certainly false, but let's not try to solve every problem today.

Does anything do this today? As far as I can tell, Intel's Boot Guard implementation does. Based on publicly available documentation I can't find any evidence that AMD's Platform Secure Boot does (it does the verification, but it doesn't measure the policy beforehand, so it seems spoofable), but I could be wrong there. I haven't found any general purpose non-x86 parts that do, but this is in the realm of things that SoC vendors seem to believe is some sort of value-add that can only be documented under NDAs, so please do prove me wrong. And then there are add-on solutions like Titan, where we delegate the initial measurement and validation to a separate piece of hardware that measures the firmware as the CPU reads it, rather than requiring that the CPU do it.

But, overall, the situation isn't great. On many platforms there's simply no way to prove that you booted the code you expected to boot. People have designed elaborate security implementations that can be bypassed in a number of ways.

[1] In this respect it is extremely similar to "Zero Trust"
[2] This is a bit of an oversimplification - once we get into dynamic roots of trust like Intel's TXT this story gets more complicated, but let's stick to the simple case today
[3] I'm kind of using "firmware" in an x86ish manner here, so for embedded devices just think of "firmware" as "the first code executed out of flash and signed by someone other than the SoC vendor"
[4] In the Intel case this isn't strictly true, since the keys are stored in the motherboard chipset rather than the CPU, and so taking a board with Boot Guard enabled and swapping out the CPU won't disable Boot Guard because the CPU reads the configuration from the chipset. But many mobile Intel parts have the chipset in the same package as the CPU, so in theory swapping out that entire package would disable Boot Guard. I am not good enough at soldering to demonstrate that.

comments

Debian s cloud-images are using systemd-networkd as their default network stack in Bookworm. A slim and feature rich networking daemon that comes included with Systemd itself. Debian s cloud-images are deploying Netplan on top of this as an easy-to-use, declarative control layer. If you want to experiment with systemd-networkd and Netplan on Debian, this can be done easily in QEMU using the official images. To start, you need to download the relevant .qcow2 Debian cloud-image from: https://cloud.debian.org/images/cloud/bookworm/latest/

$ wget https://cloud.debian.org/images/cloud/bookworm/latest/debian-12-generic-amd64.qcow2

Prepare a cloud image Next, you need to prepare some configuration files for cloud-init and Netplan, to prepare a data-source (seed.img) for your local cloud-image.

$ cat > meta.yaml <<EOF
instance-id: debian01
local-hostname: cloudimg
EOF

$ cat > user.yaml <<EOF
#cloud-config
ssh_pwauth: true
password: test
chpasswd:
  expire: false
EOF

$ cat > netplan.yaml <<EOF
network:
  version: 2
  ethernets:
    id0:
      match:
        macaddress: "ca:fe:ca:fe:00:aa"
      dhcp4: true
      dhcp6: true
      set-name: lan0
EOF

Once all configuration is prepared, you can create the local data-source image, using the cloud-localds tool from the cloud-image-utils package:

$ cloud-localds --network-config=netplan.yaml seed.img user.yaml meta.yaml

Launch the local VM Now, everything is prepared to launch a QEMU VM with two NICs and do some experimentation! The following command will launch an ephemeral environment for you, keeping the original Debian cloud-image untouched. If you want to preserve any changes on disk, you can remove the trailing -snapshot parameter.

$ qemu-system-x86_64 \
  -machine accel=kvm,type=q35 \
  -cpu host \
  -m 2G \
  -device virtio-net-pci,netdev=net0,mac=ca:fe:ca:fe:00:aa \
  -netdev user,id=net0,hostfwd=tcp::2222-:22 \
  -nic user,model=virtio-net-pci,mac=f0:0d:ca:fe:00:bb \
  -drive if=virtio,format=qcow2,file=debian-12-generic-amd64.qcow2 \
  -drive if=virtio,format=raw,file=seed.img -snapshot

We set up the default debian user account through cloud-init s user-data configuration above, so you can now login to the system, using that user with the (very unsafe!) password test .

$ ssh -o "StrictHostKeyChecking=no" -o "UserKnownHostsFile=/dev/null" -p 2222 debian@localhost # password: test

Experience Netplan and systemd-networkd Once logged in successfully, you can execute the netplan status command to check the system s network configuration, as configured through cloud-init s netplan.yaml passthrough. So you ve already used Netplan at this point implicitly and it did all the configuration of systemd-networkd for you in the background!

debian@cloudimg:~$ sudo netplan status -a
     Online state: online
    DNS Addresses: 10.0.2.3 (compat)
       DNS Search: .
   1: lo ethernet UNKNOWN/UP (unmanaged)
      MAC Address: 00:00:00:00:00:00
        Addresses: 127.0.0.1/8
                   ::1/128
           Routes: ::1 metric 256
   2: enp0s2 ethernet DOWN (unmanaged)
      MAC Address: f0:0d:ca:fe:00:bb (Red Hat, Inc.)
   3: lan0 ethernet UP (networkd: id0)
      MAC Address: ca:fe:ca:fe:00:aa (Red Hat, Inc.)
        Addresses: 10.0.2.15/24 (dhcp)
                   fec0::c8fe:caff:fefe:aa/64
                   fe80::c8fe:caff:fefe:aa/64 (link)
    DNS Addresses: 10.0.2.3
           Routes: default via 10.0.2.2 from 10.0.2.15 metric 100 (dhcp)
                   10.0.2.0/24 from 10.0.2.15 metric 100 (link)
                   10.0.2.2 from 10.0.2.15 metric 100 (dhcp, link)
                   10.0.2.3 from 10.0.2.15 metric 100 (dhcp, link)
                   fe80::/64 metric 256
                   fec0::/64 metric 100 (ra)
                   default via fe80::2 metric 100 (ra)

As you can see from this output, the lan0 interface is configured via the id0 Netplan ID to be managed by systemd-networkd. Compare this data to the netplan.yaml file above, the networkctl output, the local Netplan configuration in /etc/netplan/ and the auto-generated systemd-networkd configuration.

debian@cloudimg:~$ networkctl 
IDX LINK   TYPE     OPERATIONAL SETUP     
  1 lo     loopback carrier     unmanaged
  2 enp0s2 ether    off         unmanaged
  3 lan0   ether    routable    configured
3 links listed.
debian@cloudimg:~$ cat /etc/netplan/50-cloud-init.yaml 
# [...]
network:
    ethernets:
        id0:
            dhcp4: true
            dhcp6: true
            match:
                macaddress: ca:fe:ca:fe:00:aa
            set-name: lan0
    version: 2

debian@cloudimg:~$ ls -l /run/systemd/network/
total 8
-rw-r--r-- 1 root root  78 Jul  5 15:23 10-netplan-id0.link
-rw-r--r-- 1 root root 137 Jul  5 15:23 10-netplan-id0.network

Now you can go ahead and try something more advanced, like link aggregation, using the second NIC that you configured for this QEMU VM and explore all the possibilities of Netplan on Debian, by checking the Netplan YAML documentation.

Over the last month I ve performed some market research to better understand the potential for co2mon.nz and to help me decide whether the product I ve built has a fit with the market or not. The key conclusions I ve drawn from this work are:

• Air quality is acknowledged as important, but monitoring it is not an urgent or pressing problem for most people.
• Most of the value is seen in the hardware rather than the software service.

Keep reading to hear more about the results that lead to those conclusions.

Survey The first piece of research I undertook was a survey covering three topics: views on indoor air quality, how respondents currently monitor indoor air quality and the desired features, including price, for a CO2 monitor. The survey was distributed to my extended personal network via social media, email and word of mouth. I offered respondents the opportunity to win a year of free monitoring as an incentive and received just under 70 responses overall - the lucky winner of that prize was Sam H of Auckland whose shiny new CO2 monitor will be in the mail shortly.

Views on indoor air quality

• Nearly all respondents strongly agreed that clean, fresh indoor air is important for avoiding sickness and enabling our best work, learning and general cognitive performance, with not a single negative response.
• 25% of respondents indicated they did not have a good understanding of the quality of the indoor air they were breathing versus 43% who indicated they had a good understanding of their indoor air quality.
• Nearly 70% of respondents agreed (and greater than 40% strongly agreed) that real-time monitoring is beneficial and worth investing time and money in providing, with a similar distribution of responses agreeing it should be required in all shared indoor spaces.

Current ventilation monitoring approaches

• For the home setting, using our senses was the most common method of understanding air quality, and only 6% of respondents were unhappy with their ability to monitor ventilation at home.
• At work, trusting the owner of the building to monitor ventilation was the most common method, although using our senses and some personally collected data also featured for 20% of respondents. While the majority of respondents saw some room for improvement here, less than 20% of respondents were unsatisfied with the ability to monitor ventilation at work.
• In shared public spaces using our senses and trusting the owner were equally popular with very little use of any data reported. The majority of respondents (40%) were unsatisfied with this situation with 34% seeing some room for improvement and very few being satisfied overall.

CO2 monitoring product features

• A screen and WiFi were both strongly supported features with less than 10% of respondents seeing them as irrelevant and a large majority of answers skewing towards essential.
• Coloured lights providing a quick indication were not viewed as important by 13% of respondents and while the majority of answers were towards essential there was also a large (22%) set of respondents who were indifferent to this feature.
• The ability to access measurements and reports via a web interface was very mixed. Around 20% of respondents reported the feature as irrelevant, 20% essential with the majority seeing it as useful but mot essential.
• Almost all respondents strongly indicated that additional air quality metrics beyond CO2 were important to collect.
• Respondents mostly indicated the proposed prices are too high (64%), with essentially no responses suggesting they were too low and the balance (43%) in the middle. Only 5% of respondents indicated a preference for a rental option over a straight purchase.

Advertising In parallel with the survey, I worked with my cousin who runs a marketing agency, The Asset, to place some Facebook ads aiming to systematically evaluate what combination of images and text would draw the best response. It s been an interesting process - despite working for Google for 15 years, I know relatively little about the day to day practice of online advertising! I think we re about 50% of the way through that process of systematically building a funnel of traffic, it s been a steep learning curve and its clear there s significantly more thought and time that would need to be invested into this were it to be the primary driver of sales for a business. It s interested to see how what resonates or doesn t resonate with the audience is often completely different to what I expect, confirming the importance of having a process to evaluate and tweak how the advertising runs. After just under 2 weeks of advertising with a daily budget in the $20 - $30 range, my ads have had just under 17k impressions by 10k distinct people resulting in 76 visits to the co2mon.nz website, and zero sales. The ads themselves received 233 clicks, so there s clearly a lot of room for further improvement and revision of the ad text itself to present a more compelling message. Unfortunately the most common response and feedback to the ads themselves has been comments arguing that CO2 is wonderful, climate change is invented and all our problems would be solved if we had more CO2 everywhere. Tedious to deal with, but also useful reminder about awareness and interest in the problem to contrast with the results from the survey of my extended personal network!

Feedback from other conversations In addition to the survey and advertising I ve had conversations with some local air conditioning and ventilation businesses as well as a commercial building management firm - all providing similar feedback to the results from the survey - acknowledgement that air quality is important and relatively immaturely measured currently, but low urgency or pain to change or remedy that situation. Another interesting point that s come up in conversations with various small business owners is what to do if or when the monitoring shows a ventilation problem? The obvious answer of opening the windows more does not seem to be particularly well received. Without a compelling solution to offer to the potential problem that the monitoring might reveal I often sense a reluctance from people to invest too much time and money in something which may create a problem in a space they don t currently see as urgent.

Conclusions The responses are interesting and surprising to me a in a few ways (no interest in rental, favouring web interface over app), but at the end of the day lead to the two conclusions described above: Air quality is acknowledged as important, but monitoring it is not an urgent or pressing problem for most people. At home and work the majority of people are OK with relying on their senses or trusting someone else to maintain ventilation. They wouldn t object to improvements, but the feedback is that ventilation monitoring is not a problem people are actively looking to solve. The number of people who do see this as an urgent enough problem to invest money into solving is low - even within the biased sample of my extended network. There is a stronger set of evidence for the problem being seen as more urgent by the users of shared public spaces - but I ve not been able to find any evidence that the owners and managers of those spaces feel the same urgency or duty of care towards their users to invest in this space. Most of the opportunity is in the hardware rather than the software service. This signal comes through in the feedback on the pricing (preferring outright purchase vs rental), but it s also been directly expressed in the free-form comments and other conversations I ve had and the the relative importance given to the physical product features over the web/app interfaces in the survey results.

Wrap Up I m glad I finally spent the time doing this research, particularly the survey, these are good lessons to learn, even if I should have taken the time to learn them a year ago - so I can write that reminder (do your research before building a product) down as a key outcome of this process too! Stay tuned for more details on the other work I ve been doing recently on the hardware side of co2mon.nz and what these results mean for my overall plans. As always, I d love to hear from you if these results give you ideas or questions you d like to discuss.

Just a few days back we came to know about the horrific Train Crash that happened in Odisha (Orissa). There are some things that are known and somethings that can be inferred by observance. Sadly, it seems the incident is going to be covered up . Some of the facts that have not been contested in the public domain are that there were three lines. One loop line on which the Goods Train was standing and there was an up and a down line. So three lines were there. Apparently, the signalling system and the inter-locking system had issues as highlighted by an official about a month back. That letter, thankfully is in the public domain and I have downloaded it as well. It s a letter that goes to 4 pages. The RW is incensed that the letter got leaked and is in public domain. They are blaming everyone and espousing conspiracy theories rather than taking the minister to task. Incidentally, the Minister has three ministries that he currently holds. Ministry of Communication, Ministry of Electronics and Information Technology (MEIT), and Railways Ministry. Each Ministry in itself is important and has revenues of more than 6 lakh crore rupees. How he is able to do justice to all the three ministries is beyond me The other thing is funds both for safety and relaying of tracks has been either not sanctioned or unutilized. In fact, CAG and the Railway Brass had shared how derailments have increased and unfulfilled vacancies but they were given no importance In fact, not talking about safety in the recently held Chintan Shivir (brainstorming session) tells you how much the Govt. is serious about safety. In fact, most of the programme was on high speed rail which is a white elephant. I have shared a whitepaper done by RW in the U.S. that tells how high-speed rail doesn t make economic sense. And that is an economy that is 20 times + the Indian Economy. Even the Chinese are stopping with HSR as it doesn t make economic sense. Incidentally, Air Fares again went up 200% yesterday. Somebody shared in the region of 20k + for an Air ticket from their place to Bangalore Coming back to the story itself. the Goods Train was on the loopline. Some say it was a little bit on the outer, some say otherwise, but it is established that it was on the loopline. This is standard behavior on and around Railway Stations around the world. Whether it was in the Inner or Outer doesn t make much of a difference with what happened next. The first train that collided with the goods train was the 12864 (SMVB-HWH) Yashwantpur Howrah Express and got derailed on to the next track where from the opposite direction 12841 (Shalimar- Bangalore) Coramandel Express was coming. Now they have said that around 300 people have died and that seems to be part of the cover-up. Both the trains are long trains, having between 23 odd coaches each. Even if you have reserved tickets you have 80 odd people in a coach and usually in most of these trains, it is at least double of that. Lot of money goes to TC and then above (Corruption). The Railway fares have gone up enormously but that s a question for perhaps another time . So at the very least, we could be looking at more than 1000 people having died. The numbers are being under-reported so that nobody has to take responsibility. The Railways itself has told that it is unable to identify 80% of the people who have died. This means that 80% were unreserved ticket holders or a majority of them. There have been disturbing images as how bodies have been flung over on tractors and whatnot to be either buried or cremated without a thought. We are in peak summer season so bodies will start to rot within 24-48 hours No arrangements made to cool the bodies and take some information and identifying marks or whatever. The whole thing being done in a very callous manner, not giving dignity to even those who have died for no fault of their own. The dissent note also tells that a cover-up is also in the picture. Apparently, India doesn t have nor does it feel to have a need for something like the NTSB that the U.S. used when it hauled both the plane manufacturer (Boeing) and the FAA when the 737 Max went down due to improper data collection and sharing of data with pilots. And with no accountability being fixed to Minister or any of the senior staff, a small junior staff person may be fired. Perhaps the same official that actually told them about the signal failures almost 3 months back There were and are also some reports that some jugaadu /temporary fixes were applied to signalling and inter-locking just before this incident happened. I do not know nor confirm one way or the other if the above happened. I can however point out that if such a thing happened, then usually a traffic block is announced and all traffic on those lines are stopped. This has been the thing I know for decades. Traveling between Mumbai and Pune multiple times over the years am aware about traffic block. If some repair work was going on and it wasn t able to complete the work within the time-frame then that may well have contributed to the accident. There is also a bit muddying of the waters where it is being said that one of the trains was 4 hours late, which one is conflicting stories. On top of the whole thing, they have put the case to be investigated by CBI and hinting at sabotage. They also tried to paint a religious structure as mosque, later turned out to be a temple. The RW says done by Muslims as it was Friday not taking into account as shared before that most Railway maintenance works are usually done between Friday Monday. This is a practice followed not just in India but world over. There has been also move over a decade to remove wooden sleepers and have concrete sleepers. Unlike the wooden ones they do not expand and contract as much and their life is much more longer than the wooden ones. Funds had been marked (although lower than last few years) but not yet spent. As we know in case of any accident, it is when all the holes in cheese line up it happens. Fukushima is a great example of that, no sea wall even though Japan is no stranger to Tsunamis. External power at the same level as the plant. (10 meters above sea-level), no training for cascading failures scenarios which is what happened. The Days mini-series shares some but not all the faults that happened at Fukushima and the Govt. response to it. There is a difference though, the Japanese Prime Minister resigned on moral grounds. Here, nor the PM, nor the Minister would be resigning on moral grounds or otherwise :(. Zero accountability and that was partly a natural disaster, here it s man-made. In fact, both the Minister and the Prime Minister arrived with their entourages, did a PR blitzkrieg showing how concerned they are. Within 50 hours, the lines were cleared. The part-time Railway Minister shared that he knows the root cause and then few hours later has given the case to CBI. All are saying, wait for the inquiry report. To date, none of the accidents even in this Govt. has produced an investigation report. And even if it did, I am sure it will whitewash as it did in case of Adani as I had shared before in the previous blog post. Incidentally, it is reported that Adani paid off some of its debt, but when questioned as to where they got the money, complete silence on that part :(. As can be seen cover-up after cover-up FWIW, the Coramandel Express is known as the Migrant train so has a huge number of passengers, the other one which was collided with is known as sick train as huge number of cancer patients use it to travel to Chennai and come back

Demonetization 2.0 Few days back, India announced demonetization 2.0. Surprised, don t be. Apparently, INR 2k/- is being used for corruption and Mr. Modi is unhappy about it. He actually didn t like the INR 2k/- note but was told that it was needed, who told him we are unaware to date. At that time the RBI Governor was Mr. Urjit Patel who didn t say about INR 2k/- he had said that INR 1k/- note redesigned would come in the market. That has yet to happen. What has happened is that just like INR 500/- and INR 1k/- note is concerned, RBI will no longer honor the INR 2k/- note. Obviously, this has made our neighbors angry, namely Nepal, Sri Lanka, Bhutan etc. who do some trading with us. 2 Deccan herald columns share the limelight on it. Apparently, India wants to be the world s currency reserve but doesn t want to play by the rules for everyone else. It was pointed out that both the U.S. and Singapore had retired their currencies but they will honor that promise even today. The Singapore example being a bit closer (as it s in Asia) is perhaps a bit more relevant than the U.S. one. Singapore retired the SGD $10,000 as of 2014 but even in 2022, it remains as legal tender. They also retired the SGD $1,000 in 2020 but still remains legal tender.

So let s have a fictitious example to illustrate what is meant by what Singapore has done. Let s say I go to Singapore, rent a flat, and find a $1000 note in that house somewhere. Both practically and theoretically, I could go down to any of the banks, get the amount transferred to my wallet, bank account etc. and nobody will question. Because they have promised the same. Interestingly, the Singapore Dollar has been pretty resilient against the USD for quite a number of years vis-a-vis other Asian currencies. Most of the INR 2k/- notes were also found and exchanged in Gujarat in just a few days (The PM and HM s state.). I am sure you are looking into the mental gymnastics that the RW indulge in :(. What is sadder that most of the people who try to defend can t make sense one way or the other and start to name-call and get personal as they have nothing else

Disability questions dropped in NHFS-6 Just came to know today that in the upcoming National Family Health Survey-6 disability questions are being dropped. Why is this important. To put it simply, if you don t have numbers, you won t and can t make policies for them. India is one of the worst countries to live if you are disabled. The easiest way to share to draw attention is most Railway platforms are not at level with people. Just as Mick Lynch shares in the UK, the same is pretty much true for India too. Meanwhile in Europe, they do make an effort to be level so even disabled people have some dignity. If your public transport is sorted, then people would want much more and you will be obligated to provide for them as they are citizens. Here, we have had many reports of women being sexually molested when being transferred from platform to coach irrespective of their age or whatnot The main takeaway is if you do not have their voice, you won t make policies for them. They won t go away but you will make life hell for them. One thing to keep in mind that most people assume that most people are disabled from birth. This may or may not be true. For e.g. in the above triple Railways accidents, there are bound to be disabled people or newly disabled people who were healthy before the accident. The most common accident is road accidents, some involving pedestrians and vehicles or both, the easiest is Ministry of Road Transport data that says 4,00,000 people sustained injuries in 2021 alone in road mishaps. And this is in a country where even accidents are highly under-reported, for more than one reason. The biggest reason especially in 2 and 4 wheeler is the increased premium they would have to pay if in an accident, so they usually compromise with the other and pay off the Traffic Inspector. Sadly, I haven t read a new book, although there are a few books I m looking forward to have. People living in India and neighbors please be careful as more heat waves are expected. Till later.

Review: The Mimicking of Known Successes, by Malka Older

Series:	Mossa and Pleiti #1
Publisher:	Tordotcom
Copyright:	2023
ISBN:	1-250-86051-2
Format:	Kindle
Pages:	169

The Mimicking of Known Successes is a science fiction mystery novella, the first of an expected series. (The second novella is scheduled to be published in February of 2024.) Mossa is an Investigator, called in after a man disappears from the eastward platform on the 4 63' line. It's an isolated platform, five hours away from Mossa's base, and home to only four residential buildings and a pub. The most likely explanation is that the man jumped, but his behavior before he disappeared doesn't seem consistent with that theory. He was bragging about being from Valdegeld University, talking to anyone who would listen about the important work he was doing not typically the behavior of someone who is suicidal. Valdegeld is the obvious next stop in the investigation. Pleiti is a Classics scholar at Valdegeld. She is also Mossa's ex-girlfriend, making her both an obvious and a fraught person to ask for investigative help. Mossa is the last person she expected to be waiting for her on the railcar platform when she returns from a trip to visit her parents. The Mimicking of Known Successes is mostly a mystery, following Mossa's attempts to untangle the story of what happened to the disappeared man, but as you might have guessed there's a substantial sapphic romance subplot. It's also at least adjacent to Sherlock Holmes: Mossa is brilliant, observant, somewhat monomaniacal, and very bad at human relationships. All of this story except for the prologue is told from Pleiti's perspective as she plays a bit of a Watson role, finding Mossa unreadable, attractive, frustrating, and charming in turn. Following more recent Holmes adaptations, Mossa is portrayed as probably neurodivergent, although the story doesn't attach any specific labels. I have no strong opinions about this novella. It was fine? There's a mystery with a few twists, there's a sapphic romance of the second chance variety, there's a bit of action and a bit of hurt/comfort after the action, and it all felt comfortably entertaining but kind of predictable. Susan Stepney has a "passes the time" review rating, and while that may be a bit harsh, that's about where I ended up. The most interesting part of the story is the science fiction setting. We're some indefinite period into the future. Humans have completely messed up Earth to the point of making it uninhabitable. We then took a shot at terraforming Mars and messed that planet up to the point of uninhabitability as well. Now, what's left of humanity (maybe not all of it the story isn't clear) lives on platforms connected by rail lines high in the atmosphere of Jupiter. (Everyone in the story calls Jupiter "Giant" for reasons that I didn't follow, given that they didn't rename any of its moons.) Pleiti's position as a Classics scholar means that she studies Earth and its now-lost ecosystems, whereas the Modern faculty focus on their new platform life. This background does become relevant to the mystery, although exactly how is not clear at the start. I wouldn't call this a very realistic setting. One has to accept that people are living on platforms attached to artificial rings around the solar system's largest planet and walk around in shirt sleeves and only minor technological support due to "atmoshields" of some unspecified capability, and where the native atmosphere plays the role of London fog. Everything feels vaguely Edwardian, including to the occasional human porter and message runner, which matches the story concept but seems unlikely as a plausible future culture. I also disbelieve in humanity's ability to do anything to Earth that would make it less inhabitable than the clouds of Jupiter. That said, the setting is a lot of fun, which is probably more important. It's fun to try to visualize, and it has that slightly off-balance, occasionally surprising feel of science fiction settings where everyone is recognizably human but the things they consider routine and unremarkable are unexpected by the reader. This novella also has a great title. The Mimicking of Known Successes is simultaneously a reference a specific plot point from late in the story, a nod to the shape of the romance, and an acknowledgment of the Holmes pastiche, and all of those references work even better once you know what the plot point is. That was nicely done. This was not very memorable apart from the setting, but it was pleasant enough. I can't say that I'm inspired to pre-order the next novella in this series, but I also wouldn't object to reading it. If you're in the mood for gender-swapped Holmes in an exotic setting, you could do worse. Followed by The Imposition of Unnecessary Obstacles. Rating: 6 out of 10

Docker and other container systems by default restrict access to devices on the host. They used to do this with cgroups with the cgroup v1 system, however, the second version of cgroups removed this controller and the man page says:

Cgroup v2 device controller has no interface files and is implemented on top of cgroup BPF.

https://www.kernel.org/doc/Documentation/admin-guide/cgroup-v2.rst

That is just awesome, nothing to see here, go look at the BPF documents if you have cgroup v2. With cgroup v1 if you wanted to know what devices were permitted, you just would cat /sys/fs/cgroup/XX/devices.allow and you were done! The kernel documentation is not very helpful, sure its something in BPF and has something to do with the cgroup BPF specifically, but what does that mean? There doesn t seem to be an easy corresponding method to get the same information. So to see what restrictions a docker container has, we will have to:

1. Find what cgroup the programs running in the container belong to
2. Find what is the eBPF program ID that is attached to our container cgroup
3. Dump the eBPF program to a text file
4. Try to interpret the eBPF syntax

The last step is by far the most difficult.

Finding a container s cgroup All containers have a short ID and a long ID. When you run the docker ps command, you get the short id. To get the long id you can either use the --no-trunc flag or just guess from the short ID. I usually do the second.

$ docker ps 
CONTAINER ID   IMAGE            COMMAND       CREATED          STATUS          PORTS     NAMES
a3c53d8aaec2   debian:minicom   "/bin/bash"   19 minutes ago   Up 19 minutes             inspiring_shannon

So the short ID is a3c53d8aaec2 and the long ID is a big ugly hex string starting with that. I generally just paste the relevant part in the next step and hit tab. For this container the cgroup is /sys/fs/cgroup/system.slice/docker-a3c53d8aaec23c256124f03d208732484714219c8b5f90dc1c3b4ab00f0b7779.scope/ Notice that the last directory has docker- then the short ID. If you re not sure of the exact path. The /sys/fs/cgroup is the cgroup v2 mount point which can be found with mount -t cgroup2 and then rest is the actual cgroup name. If you know the process running in the container then the cgroup column in ps will show you.

$ ps -o pid,comm,cgroup 140064
    PID COMMAND         CGROUP
 140064 bash            0::/system.slice/docker-a3c53d8aaec23c256124f03d208732484714219c8b5f90dc1c3b4ab00f0b7779.scope

Either way, you will have your cgroup path.

eBPF programs and cgroups Next we will need to get the eBPF program ID that is attached to our recently found cgroup. To do this, we will need to use the bpftool. One thing that threw me for a long time is when the tool talks about a program or a PROG ID they are talking about the eBPF programs, not your processes! With that out of the way, let s find the prog id.

$ sudo bpftool cgroup list /sys/fs/cgroup/system.slice/docker-a3c53d8aaec23c256124f03d208732484714219c8b5f90dc1c3b4ab00f0b7779.scope/
ID       AttachType      AttachFlags     Name
90       cgroup_device   multi

Our cgroup is attached to eBPF prog with ID of 90 and the type of program is cgroup _device.

Dumping the eBPF program Next, we need to get the actual code that is run every time a process running in the cgroup tries to access a device. The program will take some parameters and will return either a 1 for yes you are allowed or a zero for permission denied. Don t use the file option as it dumps the program in binary format. The text version is hard enough to understand.

sudo bpftool prog dump xlated id 90 > myebpf.txt

Congratulations! You now have the eBPF program in a human-readable (?) format.

Interpreting the eBPF program The eBPF format as dumped is not exactly user friendly. It probably helps to first go and look at an example program to see what is going on. You ll see that the program splits type (lower 4 bytes) and access (higher 4 bytes) and then does comparisons on those values. The eBPF has something similar:

   0: (61) r2 = *(u32 *)(r1 +0)
   1: (54) w2 &= 65535
   2: (61) r3 = *(u32 *)(r1 +0)
   3: (74) w3 >>= 16
   4: (61) r4 = *(u32 *)(r1 +4)
   5: (61) r5 = *(u32 *)(r1 +8)

What we find is that once we get past the first few lines filtering the given value that the comparison lines have:

• r2 is the device type, 1 is block, 2 is character.
• r3 is the device access, it s used with r1 for comparisons after masking the relevant bits. mknod, read and write are 1,2 and 3 respectively.
• r4 is the major number
• r5 is the minor number

For a even pretty simple setup, you are going to have around 60 lines of eBPF code to look at. Luckily, you ll often find the lines for the command options you added will be near the end, which makes it easier. For example:

  63: (55) if r2 != 0x2 goto pc+4
  64: (55) if r4 != 0x64 goto pc+3
  65: (55) if r5 != 0x2a goto pc+2
  66: (b4) w0 = 1
  67: (95) exit

This is a container using the option --device-cgroup-rule='c 100:42 rwm'. It is checking if r2 (device type) is 2 (char) and r4 (major device number) is 0x64 or 100 and r5 (minor device number) is 0x2a or 42. If any of those are not true, move to the next section, otherwise return with 1 (permit). We have all access modes permitted so it doesn t check for it. The previous example has all permissions for our device with id 100:42, what about if we only want write access with the option --device-cgroup-rule='c 100:42 r'. The resulting eBPF is:

  63: (55) if r2 != 0x2 goto pc+7  
  64: (bc) w1 = w3
  65: (54) w1 &= 2
  66: (5d) if r1 != r3 goto pc+4
  67: (55) if r4 != 0x64 goto pc+3
  68: (55) if r5 != 0x2a goto pc+2
  69: (b4) w0 = 1
  70: (95) exit

The code is almost the same but we are checking that w3 only has the second bit set, which is for reading, effectively checking for X==X&2. It s a cautious approach meaning no access still passes but multiple bits set will fail.

The device option docker run allows you to specify files you want to grant access to your containers with the --device flag. This flag actually does two things. The first is to great the device file in the containers /dev directory, effectively doing a mknod command. The second thing is to adjust the eBPF program. If the device file we specified actually did have a major number of 100 and a minor of 42, the eBPF would look exactly like the above snippets.

What about privileged? So we have used the direct cgroup options here, what does the --privileged flag do? This lets the container have full access to all the devices (if the user running the process is allowed). Like the --device flag, it makes the device files as well, but what does the filtering look like? We still have a cgroup but the eBPF program is greatly simplified, here it is in full:

   0: (61) r2 = *(u32 *)(r1 +0)
   1: (54) w2 &= 65535
   2: (61) r3 = *(u32 *)(r1 +0)
   3: (74) w3 >>= 16
   4: (61) r4 = *(u32 *)(r1 +4)
   5: (61) r5 = *(u32 *)(r1 +8)
   6: (b4) w0 = 1
   7: (95) exit

There is the usual setup lines and then, return 1. Everyone is a winner for all devices and access types!

Review: A Half-Built Garden, by Ruthanna Emrys

Publisher:	Tordotcom
Copyright:	2022
ISBN:	1-250-21097-6
Format:	Kindle
Pages:	340

The climate apocalypse has happened. Humans woke up to the danger, but a little bit too late. Over one billion people died. But the world on the other side of that apocalypse is not entirely grim. The corporations responsible for so much of the damage have been pushed out of society and isolated on their independent "aislands," traded with only grudgingly for the few commodities the rest of the world has not yet learned how to manufacture without them. Traditional governments have largely collapsed, although they cling to increasingly irrelevant trappings of power. In their place arose the watershed networks: a new way of living with both nature and other humans, built around a mix of anarchic consensus and direct democracy, with conservation and stewardship of the natural environment at its core. Therefore, when the aliens arrive near Bear Island on the Potomac River, they're not detected by powerful telescopes and met by military jets. Instead, their waste sets off water sensors, and they're met by the two women on call for alert duty, carrying a nursing infant and backed by the real-time discussion and consensus technology of the watershed's dandelion network. (Emrys is far from the first person to name something a "dandelion network," so be aware that the usage in this book seems unrelated to the charities or blockchain network.) This is a first contact novel, but it's one that skips over the typical focus of the subgenre. The alien Ringers are completely fluent in English down to subtle nuance of emotion and connotation (supposedly due to observation of our radio and TV signals), have translation devices, and in some cases can make our speech sounds directly. Despite significantly different body shapes, they are immediately comprehensible; differences are limited mostly to family structure, reproduction, and social norms. This is Star Trek first contact, not the type more typical of written science fiction. That feels unrealistic, but it's also obviously an authorial choice to jump directly to the part of the story that Emrys wants to write. The Ringers have come to save humanity. In their experience, technological civilization is inherently incompatible with planets. Technology will destroy the planet, and the planet will in turn destroy the species unless they can escape. They have reached other worlds multiple times before, only to discover that they were too late and everyone is already dead. This is the first time they've arrived in time, and they're eager to help humanity off its dying planet to join them in the Dyson sphere of space habitats they are constructing. Planets, to them, are a nest and a launching pad, something to eventually abandon and break down for spare parts. The small, unexpected wrinkle is that Judy, Carol, and the rest of their watershed network are not interested in leaving Earth. They've finally figured out the most critical pieces of environmental balance. Earth is going to get hotter for a while, but the trend is slowing. What they're doing is working. Humanity would benefit greatly from Ringer technology and the expertise that comes from managing closed habitat ecosystems, but they don't need rescuing. This goes over about as well as a toddler saying that playing in the road is perfectly safe. This is a fantastic hook for a science fiction novel. It does exactly what a great science fiction premise should do: takes current concerns (environmentalism, space boosterism, the debatable primacy of humans as a species, the appropriate role of space colonization, the tension between hopefulness and doomcasting about climate change) and uses the freedom of science fiction to twist them around and come at them from an entirely different angle. The design of the aliens is excellent for this purpose. The Ringers are not one alien species; they are two, evolved on different planets in the same system. The plains dwellers developed space flight first and went to meet the tree dwellers, and while their relationship is not entirely without hierarchy (the plains dwellers clearly lead on most matters), it's extensively symbiotic. They now form mixed families of both species, and have a rich cultural history of stories about first contact, interspecies conflicts and cooperation, and all the perils and misunderstandings that they successfully navigated. It makes their approach to humanity more believable to know that they have done first contact before and are building on a model. Their concern for humanity is credibly sincere. The joining of two species was wildly successful for them and they truly want to add a third. The politics on the human side are satisfyingly complicated. The watershed network may have made first contact, but the US government (in the form of NASA) is close behind, attempting to lean on its widely ignored formal power. The corporations are farther away and therefore slower to arrive, but the alien visitors have a damaged ship and need space to construct a subspace beacon and Asterion is happy to offer a site on one of its New Zealand islands. The corporate representatives are salivating at the chance to escape Earth and its environmental regulation for uncontrolled space construction and a new market of trillions of Ringers. NASA's attitude is more measured, but their representative is easily persuaded that the true future of humanity is in space. The work the watershed networks are doing is difficult, uncertain, and involves a lot of sacrifice, particularly for corporate consumer lifestyles. With such an attractive alien offer on the table, why stay and work so hard for an uncertain future? Maybe the Ringers are right. And then the dandelion networks that the watersheds use as the core of their governance and decision-making system all crash. The setup was great; I was completely invested. The execution was more mixed. There are some things I really liked, some things that I thought were a bit too easy or predictable, and several places where I wish Emrys had dug deeper and provided more detail. I thought the last third of the book fizzled a little, although some of the secondary characters Emrys introduces are delightful and carry the momentum of the story when the politics feel a bit lacking. If you tried to form a mental image of ecofeminist political science fiction with 1970s utopian sensibilities, but updated for the concerns of the 2020s, you would probably come very close to the politics of the watershed networks. There are considerably more breastfeedings and diaper changes than the average SF novel. Two of the primary characters are transgender, but with very different experiences with transition. Pronoun pins are an ubiquitous article of clothing. One of the characters has a prosthetic limb. Another character who becomes important later in the story codes as autistic. None of this felt gratuitous; the characters do come across as obsessed with gender, but in a way that I found believable. The human diversity is well-integrated with the story, shapes the characters, creates practical challenges, and has subtle (and sometimes not so subtle) political ramifications. But, and I say this with love because while these are not quite my people they're closely adjacent to my people, the social politics of this book are a very specific type of white feminist collaborative utopianism. When religion makes an appearance, I was completely unsurprised to find that several of the characters are Jewish. Race never makes a significant appearance at all. It's the sort of book where the throw-away references to other important watershed networks includes African ones, and the characters would doubtless try to be sensitive to racial issues if they came up, but somehow they never do. (If you're wondering if there's polyamory in this book, yes, yes there is, and also I suspect you know exactly what culture I'm talking about.) This is not intended as a criticism, just more of a calibration. All science fiction publishing houses could focus only on this specific political perspective for a year and the results would still be dwarfed by the towering accumulated pile of thoughtless paeans to capitalism. Ecofeminism has a long history in the genre but still doesn't show up in that many books, and we're far from exhausting the space of possibilities for what a consensus-based politics could look like with extensive computer support. But this book has a highly specific point of view, enough so that there won't be many thought-provoking surprises if you're already familiar with this school of political thought. The politics are also very earnest in a way that I admit provoked a bit of eyerolling. Emrys pushes all of the political conflict into the contrasts between the human factions, but I would have liked more internal disagreement within the watershed networks over principles rather than tactics. The degree of ideological agreement within the watershed group felt a bit unrealistic. But, that said, at least politics truly matters and the characters wrestle directly with some tricky questions. I would have liked to see more specifics about the dandelion network and the exact mechanics of the consensus decision process, since that sort of thing is my jam, but we at least get more details than are typical in science fiction. I'll take this over cynical libertarianism any day. Gender plays a huge role in this story, enough so that you should avoid this book if you're not interested in exploring gender conceptions. One of the two alien races is matriarchal and places immense social value on motherhood, and it's culturally expected to bring your children with you for any important negotiation. The watersheds actively embrace this, or at worst find it comfortable to use for their advantage, despite a few hints that the matriarchy of the plains aliens may have a very serious long-term demographic problem. In an interesting twist, it's the mostly-evil corporations that truly challenge gender roles, albeit by turning it into an opportunity to sell more clothing. The Asterion corporate representatives are, as expected, mostly the villains of the plot: flashy, hierarchical, consumerist, greedy, and exploitative. But gender among the corporations is purely a matter of public performance, one of a set of roles that you can put on and off as you choose and signal with clothing. They mostly use neopronouns, change pronouns as frequently as their clothing, and treat any question of body plumbing as intensely private. By comparison, the very 2020 attitudes of the watersheds towards gender felt oddly conservative and essentialist, and the main characters get flustered and annoyed by the ever-fluid corporate gender presentation. I wish Emrys had done more with this. As you can tell, I have a lot of thoughts and a lot of quibbles. Another example: computer security plays an important role in the plot and was sufficiently well-described that I have serious questions about the system architecture and security model of the dandelion networks. But, as with decision-making and gender, the more important takeaway is that Emrys takes enough risks and describes enough interesting ideas that there's a lot of meat here to argue with. That, more than getting everything right, is what a good science fiction novel should do. A Half-Built Garden is written from a very specific political stance that may make it a bit predictable or off-putting, and I thought the tail end of the book had some plot and resolution problems, but arguing with it was one of the more intellectually satisfying science fiction reading experiences I've had recently. You have to be in the right mood, but recommended for when you are. Rating: 7 out of 10

Welcome to the April 2023 report from the Reproducible Builds project! In these reports we outline the most important things that we have been up to over the past month. And, as always, if you are interested in contributing to the project, please visit our Contribute page on our website.

General news Trisquel is a fully-free operating system building on the work of Ubuntu Linux. This month, Simon Josefsson published an article on his blog titled Trisquel is 42% Reproducible!. Simon wrote:

The absolute number may not be impressive, but what I hope is at least a useful contribution is that there actually is a number on how much of Trisquel is reproducible. Hopefully this will inspire others to help improve the actual metric.

Simon wrote another blog post this month on a new tool to ensure that updates to Linux distribution archive metadata (eg. via apt-get update) will only use files that have been recorded in a globally immutable and tamper-resistant ledger. A similar solution exists for Arch Linux (called pacman-bintrans) which was announced in August 2021 where an archive of all issued signatures is publically accessible.
Joachim Breitner wrote an in-depth blog post on a bootstrap-capable GHC, the primary compiler for the Haskell programming language. As a quick background to what this is trying to solve, in order to generate a fully trustworthy compile chain, trustworthy root binaries are needed and a popular approach to address this problem is called bootstrappable builds where the core idea is to address previously-circular build dependencies by creating a new dependency path using simpler prerequisite versions of software. Joachim takes an somewhat recursive approach to the problem for Haskell, leading to the inadvertently humourous question: Can I turn all of GHC into one module, and compile that? Elsewhere in the world of bootstrapping, Janneke Nieuwenhuizen and Ludovic Court s wrote a blog post on the GNU Guix blog announcing The Full-Source Bootstrap, specifically:

[ ] the third reduction of the Guix bootstrap binaries has now been merged in the main branch of Guix! If you run guix pull today, you get a package graph of more than 22,000 nodes rooted in a 357-byte program something that had never been achieved, to our knowledge, since the birth of Unix.

More info about this change is available on the post itself, including:

The full-source bootstrap was once deemed impossible. Yet, here we are, building the foundations of a GNU/Linux distro entirely from source, a long way towards the ideal that the Guix project has been aiming for from the start. There are still some daunting tasks ahead. For example, what about the Linux kernel? The good news is that the bootstrappable community has grown a lot, from two people six years ago there are now around 100 people in the #bootstrappable IRC channel.

Michael Ablassmeier created a script called pypidiff as they were looking for a way to track differences between packages published on PyPI. According to Micahel, pypidiff uses diffoscope to create reports on the published releases and automatically pushes them to a GitHub repository. This can be seen on the pypi-diff GitHub page (example).
Eleuther AI, a non-profit AI research group, recently unveiled Pythia, a collection of 16 Large Language Model (LLMs) trained on public data in the same order designed specifically to facilitate scientific research. According to a post on MarkTechPost:

Pythia is the only publicly available model suite that includes models that were trained on the same data in the same order [and] all the corresponding data and tools to download and replicate the exact training process are publicly released to facilitate further research.

These properties are intended to allow researchers to understand how gender bias (etc.) can affected by training data and model scale.
Back in February s report we reported on a series of changes to the Sphinx documentation generator that was initiated after attempts to get the alembic Debian package to build reproducibly. Although Chris Lamb was able to identify the source problem and provided a potential patch that might fix it, James Addison has taken the issue in hand, leading to a large amount of activity resulting in a proposed pull request that is waiting to be merged.
WireGuard is a popular Virtual Private Network (VPN) service that aims to be faster, simpler and leaner than other solutions to create secure connections between computing devices. According to a post on the WireGuard developer mailing list, the WireGuard Android app can now be built reproducibly so that its contents can be publicly verified. According to the post by Jason A. Donenfeld, the F-Droid project now does this verification by comparing their build of WireGuard to the build that the WireGuard project publishes. When they match, the new version becomes available. This is very positive news.
Author and public speaker, V. M. Brasseur published a sample chapter from her upcoming book on corporate open source strategy which is the topic of Software Bill of Materials (SBOM):

A software bill of materials (SBOM) is defined as a nested inventory for software, a list of ingredients that make up software components. When you receive a physical delivery of some sort, the bill of materials tells you what s inside the box. Similarly, when you use software created outside of your organisation, the SBOM tells you what s inside that software. The SBOM is a file that declares the software supply chain (SSC) for that specific piece of software. [ ]

Several distributions noticed recent versions of the Linux Kernel are no longer reproducible because the BPF Type Format (BTF) metadata is not generated in a deterministic way. This was discussed on the #reproducible-builds IRC channel, but no solution appears to be in sight for now.

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Community news On our mailing list this month:

• Larry Doolittle shared an interesting puzzle with the group where three bytes in a .zip file were different between two builds.
• Alexis PM wrote a message as they had observed a difference between binaries available in the Debian archive and the ones on tests.reproducible-builds.org. The thread generated a number of replies, including interesting responses from Vagrant Cascadian [ ] and kpcyrd [ ].

Holger Levsen gave a talk at foss-north 2023 in Gothenburg, Sweden on the topic of Reproducible Builds, the first ten years. Lastly, there were a number of updates to our website, including:

• Chris Lamb attempted a number of ways to try and fix literal : .lead appearing in the page [ ][ ][ ], made all the Back to who is involved links italics [ ], and corrected the syntax of the _data/sponsors.yml file [ ].
• Holger Levsen added his recent talk [ ], added Simon Josefsson, Mike Perry and Seth Schoen to the contributors page [ ][ ][ ], reworked the People page a little [ ] [ ], as well as fixed spelling of Arch Linux [ ].

Lastly, Mattia Rizzolo moved some old sponsors to a former section [ ] and Simon Josefsson added Trisquel GNU/Linux. [ ]

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Debian

• Vagrant Cascadian reported on the Debian s build-essential package set, which was inspired by how close we are to making the Debian build-essential set reproducible and how important that set of packages are in general . Vagrant mentioned that: I have some progress, some hope, and I daresay, some fears . [ ]
• Debian Developer Cyril Brulebois (kibi) filed a bug against snapshot.debian.org after they noticed that there are many missing dinstalls that is to say, the snapshot service is not capturing 100% of all of historical states of the Debian archive. This is relevant to reproducibility because without the availability historical versions, it is becomes impossible to repeat a build at a future date in order to correlate checksums. .
• 20 reviews of Debian packages were added, 21 were updated and 5 were removed this month adding to our knowledge about identified issues. Chris Lamb added a new build_path_in_line_annotations_added_by_ruby_ragel toolchain issue. [ ]
• Mattia Rizzolo announced that the data for the stretch archive on tests.reproducible-builds.org has been archived. This matches the archival of stretch within Debian itself. This is of some historical interest, as stretch was the first Debian release regularly tested by the Reproducible Builds project.

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Upstream patches The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. We endeavour to send all of our patches upstream where appropriate. This month, we wrote a large number of such patches, including:

• Bernhard M. Wiedemann:
  • ghc (workaround a parallelism-related issue)
• Jan Zerebecki:
  • ghc (report a parallelism-related issue)
• Chris Lamb:
  • #1034147 filed against ruby-regexp-parser.
• Vagrant Cascadian:
  • #1033954, #1033955 and #1033957 filed against pike8.0.
  • #1033958 and #1033959 filed against binutils.
  • #1034129 filed against lomiri-action-api.
  • #1034199 and #1034200 filed against lomiri.
  • #1034327 filed against nmodl.
  • #1034423 filed against php8.2.
  • #1034431 filed against qemu.
  • #1034499 filed against twisted.
  • #1034740 filed against boost1.74.
  • #1034892 filed against php8.2.
  • #1035324 filed against shaderc.
  • #1035329 and #1035331 filed against jackd2.

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diffoscope development diffoscope version 241 was uploaded to Debian unstable by Chris Lamb. It included contributions already covered in previous months as well a change by Chris Lamb to add a missing raise statement that was accidentally dropped in a previous commit. [ ]

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Testing framework The Reproducible Builds project operates a comprehensive testing framework (available at tests.reproducible-builds.org) in order to check packages and other artifacts for reproducibility. In April, a number of changes were made, including:

• Holger Levsen:
  • Significant work on a new Documented Jenkins Maintenance (djm) script to support logged maintenance of nodes, etc. [ ][ ][ ][ ][ ][ ]
  • Add the new APT repo url for Jenkins itself with a new signing key. [ ][ ]
  • In the Jenkins shell monitor, allow 40 GiB of files for diffoscope for the Debian experimental distribution as Debian is frozen around the release at the moment. [ ]
  • Updated Arch Linux testing to cleanup leftover files left in /tmp/archlinux-ci/ after three days. [ ][ ][ ]
  • Mark a number of nodes hosted by Oregon State University Open Source Lab (OSUOSL) as online and offline. [ ][ ][ ]
  • Update the node health checks to detect failures to end schroot sessions. [ ]
  • Filter out another duplicate contributor from the contributor statistics. [ ]
• Mattia Rizzolo:
  • Code changes to properly archive the stretch Debian distribution. [ ][ ][ ][ ]
  • Introduce the archived suites configuration option. [ ]][ ]
  • Fix the KGB bot configuration to support pyyaml 6.0 as present in Debian bookworm. [ ]

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If you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:

• IRC: #reproducible-builds on irc.oftc.net.
• Twitter: @ReproBuilds
• Mailing list: rb-general@lists.reproducible-builds.org

Gray Mountain John Grisham I have been perusing John Grisham s books, some read and some re-read again. Almost all of the books that Mr. Grisham wrote are relevant even today. The Gray Mountain talks about how mountain top removal was done in Applachia, the U.S. (South). In fact NASA made a summary which either was borrowed from this book or the author borrowed from NASA, either could be true although seems it might be the former. And this is when GOI just made a new Forest Conservation Bill 2023 which does the opposite. There are many examples of the same, the latest from my own city as an e.g. Vetal Tekdi is and was a haven for people animals, birds all kinds of ecosystem and is a vital lung of the city, one of the few remaining green spaces in the city but BJP wants to commercialize it as it has been doing for everything, I haven t been to the Himalayas since 4-5 years back as I hear the rape of the land daily. Even after Joshimath tragedy, if people are not opening the eyes what can I do The more I say, the more depressed I will become so will leave it for now. In many ways the destruction seems similar to the destruction that happened in Brazil under Jair Bolsonaro. So as can be seen from what I have shared this book was mostly about environment and punitive damages and also how punitive damages have been ceiling in America (South). This was done via lobbying by the coal groups and apparently destroyed people s lives, communities, even whole villages. It also shared how most people called black lung and how those claims had been denied by Coal Companies all the time. And there are hardly any unions. While the book itself is a fiction piece, there is a large amount of truth in it. And that is one of the reasons people write a fiction book. You could write about reality using fictional names and nobody can sue you while you set the reality as it is. In many ways, it is a tell-all.

The Testament John Grisham One of the things I have loved about John Grisham is he understands human condition. In this book it starts with an eccentric billionaire who makes a will which leaves all his property to an illegitimate child who coincidentally also lives in Brazil, she is a missionary. The whole book is about human failings as well as about finding the heir. I am not going to give much detail as the book itself is fun.

The Appeal John Grisham In this, we are introduced to a company that does a chemical spill for decades and how that leads to lobbying and funding Judicial elections. It does go into quite a bit of length how private money coming from Big business does all kind of shady things to get their person elected to the Supreme Court. Sadly, this seems to happen all the time, for e.g. two weeks ago. This piece from the Atlantic also says the same. Again, won t tell as there is a bit of irony at the end of the book.

The Rainmaker John Grisham This in short is about how Insurance Companies stiff people. It s a wonderful story that has all people in grey including our hero. An engaging book that sorta tells how the Insurance Industry plays the game. In India, the companies are safe as they ask for continuance for years together and their object is to delay the hearings till the grandchildren are not alive unlike in the U.S. or UK. It also does tell how more lawyers are there then required. Both of which are the same in my country.

The Litigators John Grisham This one is about Product Liability, both medicines as well as toys for young kids. What I do find funny a bit is how the law in States allows people to file cases but doesn t protect people while in EU they try their best that if there is any controversy behind any medicine or product, they will simply ban it. Huge difference between the two cultures.

Evolution no longer part of Indian Education A few days ago, NCERT (one of the major bodies) that looks into Indian Education due to BJP influence has removed Darwin s Theory of Evolution. You can t even debate because the people do not understand adaptability. So the only conclusion is that Man suddenly appeared out of nowhere. If that is so, then we are the true aliens. They discard the notion that we and Chimpanzees are similar. Then they also have to discard this finding that genetically we are 96% similar.

This post serves as a report from my attendance to Kubecon and CloudNativeCon 2023 Europe that took place in Amsterdam in April 2023. It was my second time physically attending this conference, the first one was in Austin, Texas (USA) in 2017. I also attended once in a virtual fashion. The content here is mostly generated for the sake of my own recollection and learnings, and is written from the notes I took during the event. The very first session was the opening keynote, which reunited the whole crowd to bootstrap the event and share the excitement about the days ahead. Some astonishing numbers were announced: there were more than 10.000 people attending, and apparently it could confidently be said that it was the largest open source technology conference taking place in Europe in recent times. It was also communicated that the next couple iteration of the event will be run in China in September 2023 and Paris in March 2024. More numbers, the CNCF was hosting about 159 projects, involving 1300 maintainers and about 200.000 contributors. The cloud-native community is ever-increasing, and there seems to be a strong trend in the industry for cloud-native technology adoption and all-things related to PaaS and IaaS. The event program had different tracks, and in each one there was an interesting mix of low-level and higher level talks for a variety of audience. On many occasions I found that reading the talk title alone was not enough to know in advance if a talk was a 101 kind of thing or for experienced engineers. But unlike in previous editions, I didn t have the feeling that the purpose of the conference was to try selling me anything. Obviously, speakers would make sure to mention, or highlight in a subtle way, the involvement of a given company in a given solution or piece of the ecosystem. But it was non-invasive and fair enough for me. On a different note, I found the breakout rooms to be often small. I think there were only a couple of rooms that could accommodate more than 500 people, which is a fairly small allowance for 10k attendees. I realized with frustration that the more interesting talks were immediately fully booked, with people waiting in line some 45 minutes before the session time. Because of this, I missed a few important sessions that I ll hopefully watch online later. Finally, on a more technical side, I ve learned many things, that instead of grouping by session I ll group by topic, given how some subjects were mentioned in several talks. On gitops and CI/CD pipelines Most of the mentions went to FluxCD and ArgoCD. At that point there were no doubts that gitops was a mature approach and both flux and argoCD could do an excellent job. ArgoCD seemed a bit more over-engineered to be a more general purpose CD pipeline, and flux felt a bit more tailored for simpler gitops setups. I discovered that both have nice web user interfaces that I wasn t previously familiar with. However, in two different talks I got the impression that the initial setup of them was simple, but migrating your current workflow to gitops could result in a bumpy ride. This is, the challenge is not deploying flux/argo itself, but moving everything into a state that both humans and flux/argo can understand. I also saw some curious mentions to the config drifts that can happen in some cases, even if the goal of gitops is precisely for that to never happen. Such mentions were usually accompanied by some hints on how to operate the situation by hand. Worth mentioning, I missed any practical information about one of the key pieces to this whole gitops story: building container images. Most of the showcased scenarios were using pre-built container images, so in that sense they were simple. Building and pushing to an image registry is one of the two key points we would need to solve in Toolforge Kubernetes if adopting gitops. In general, even if gitops were already in our radar for Toolforge Kubernetes, I think it climbed a few steps in my priority list after the conference. Another learning was this site: https://opengitops.dev/. On etcd, performance and resource management I attended a talk focused on etcd performance tuning that was very encouraging. They were basically talking about the exact same problems we have had in Toolforge Kubernetes, like api-server and etcd failure modes, and how sensitive etcd is to disk latency, IO pressure and network throughput. Even though Toolforge Kubernetes scale is small compared to other Kubernetes deployments out there, I found it very interesting to see other s approaches to the same set of challenges. I learned how most Kubernetes components and apps can overload the api-server. Because even the api-server talks to itself. Simple things like kubectl may have a completely different impact on the API depending on usage, for example when listing the whole list of objects (very expensive) vs a single object. The conclusion was to try avoiding hitting the api-server with LIST calls, and use ResourceVersion which avoids full-dumps from etcd (which, by the way, is the default when using bare kubectl get calls). I already knew some of this, and for example the jobs-framework-emailer was already making use of this ResourceVersion functionality. There have been a lot of improvements in the performance side of Kubernetes in recent times, or more specifically, in how resources are managed and used by the system. I saw a review of resource management from the perspective of the container runtime and kubelet, and plans to support fancy things like topology-aware scheduling decisions and dynamic resource claims (changing the pod resource claims without re-defining/re-starting the pods). On cluster management, bootstrapping and multi-tenancy I attended a couple of talks that mentioned kubeadm, and one in particular was from the maintainers themselves. This was of interest to me because as of today we use it for Toolforge. They shared all the latest developments and improvements, and the plans and roadmap for the future, with a special mention to something they called kubeadm operator , apparently capable of auto-upgrading the cluster, auto-renewing certificates and such. I also saw a comparison between the different cluster bootstrappers, which to me confirmed that kubeadm was the best, from the point of view of being a well established and well-known workflow, plus having a very active contributor base. The kubeadm developers invited the audience to submit feature requests, so I did. The different talks confirmed that the basic unit for multi-tenancy in kubernetes is the namespace. Any serious multi-tenant usage should leverage this. There were some ongoing conversations, in official sessions and in the hallway, about the right tool to implement K8s-whitin-K8s, and vcluster was mentioned enough times for me to be convinced it was the right candidate. This was despite of my impression that multiclusters / multicloud are regarded as hard topics in the general community. I definitely would like to play with it sometime down the road. On networking I attended a couple of basic sessions that served really well to understand how Kubernetes instrumented the network to achieve its goal. The conference program had sessions to cover topics ranging from network debugging recommendations, CNI implementations, to IPv6 support. Also, one of the keynote sessions had a reference to how kube-proxy is not able to perform NAT for SIP connections, which is interesting because I believe Netfilter Conntrack could do it if properly configured. One of the conclusions on the CNI front was that Calico has a massive community adoption (in Netfilter mode), which is reassuring, especially considering it is the one we use for Toolforge Kubernetes. On jobs I attended a couple of talks that were related to HPC/grid-like usages of Kubernetes. I was truly impressed by some folks out there who were using Kubernetes Jobs on massive scales, such as to train machine learning models and other fancy AI projects. It is acknowledged in the community that the early implementation of things like Jobs and CronJobs had some limitations that are now gone, or at least greatly improved. Some new functionalities have been added as well. Indexed Jobs, for example, enables each Job to have a number (index) and process a chunk of a larger batch of data based on that index. It would allow for full grid-like features like sequential (or again, indexed) processing, coordination between Job and more graceful Job restarts. My first reaction was: Is that something we would like to enable in Toolforge Jobs Framework? On policy and security A surprisingly good amount of sessions covered interesting topics related to policy and security. It was nice to learn two realities:

1. kubernetes is capable of doing pretty much anything security-wise and create greatly secured environments.
2. it does not by default. The defaults are not security-strict on purpose.

It kind of made sense to me: Kubernetes was used for a wide range of use cases, and developers didn t know beforehand to which particular setup they should accommodate the default security levels. One session in particular covered the most basic security features that should be enabled for any Kubernetes system that would get exposed to random end users. In my opinion, the Toolforge Kubernetes setup was already doing a good job in that regard. To my joy, some sessions referred to the Pod Security Admission mechanism, which is one of the key security features we re about to adopt (when migrating away from Pod Security Policy). I also learned a bit more about Secret resources, their current implementation and how to leverage a combo of CSI and RBAC for a more secure usage of external secrets. Finally, one of the major takeaways from the conference was learning about kyverno and kubeaudit. I was previously aware of the OPA Gatekeeper. From the several demos I saw, it was to me that kyverno should help us make Toolforge Kubernetes more sustainable by replacing all of our custom admission controllers with it. I already opened a ticket to track this idea, which I ll be proposing to my team soon. Final notes In general, I believe I learned many things, and perhaps even more importantly I re-learned some stuff I had forgotten because of lack of daily exposure. I m really happy that the cloud native way of thinking was reinforced in me, which I still need because most of my muscle memory to approach systems architecture and engineering is from the old pre-cloud days. List of sessions I attended on the first day:

• Keynote
• Node Resource Management: The Big Picture - Sascha Grunert & Swati Sehgal, Red Hat; Alexander Kanevskiy, Intel; Evan Lezar, NVIDIA; David Porter, Google.
• How We Securely Scaled Multi-Tenancy with VCluster, Crossplane, and Argo CD - Ilia Medvedev & Kostis Kapelonis, Codefresh. (Couldn t really attend, room full)
• Flux Beyond Git: Harnessing the Power of OCI - Stefan Prodan & Hidde Beydals, Weaveworks. (Couldn t really attend, room full)
• Tutorial: Measure Twice, Cut Once: Dive Into Network Foundations the Right Way! - Marino Wijay & Jason Skrzypek, Solo.io
• Argo CD Core - A Pure GitOps Agent for Kubernetes - Alexander Matyushentsev, Akuity & Leonardo Luz Almeida, Intuit
• Kubeadm Deep Dive - Rohit Anand, NEC & Paco Xu, Dao
• Cloud Operate Multi-Tenancy Service Mesh with ArgoCD in Production - Lin Sun, Solo.io & Faseela K, Ericsson Software Technology

List of sessions I attended on the second day:

• Keynote
• Setting up Etcd with Kubernetes to Host Clusters with Thousands of Nodes - Marcel Zi ba, Isovalent & Laurent Bernaille, Datadog
• Container Is the New VM: The Paradigm Change No One Explained to You - Marga Manterola, Isovalent & Rodrigo Campos Catelin, Microsoft
• Ephemeral Clusters as a Service with ClusterAPI and GitOps - Alessandro Vozza, Solo.io & Joaquin Rodriguez, Microsoft
• Automating Configuration and Permissions Testing for GitOps with OPA Conftest - Eve Ben Ezra & Michael Hume, The New York Times
• Across Kubernetes Namespace Boundaries: Your Volumes Can Be Shared Now! - Masaki Kimura & Takafumi Takahashi, Hitachi

List of sessions I attended on third day:

• Keynote
• Prevent Embarrassing Cluster Takeovers with This One Simple Trick! - Daniele de Araujo dos Santos & Shane Lawrence, Shopify
• Hacking and Defending Kubernetes Clusters: We ll Do It LIVE!!! - Fabian Kammel & James Cleverley-Prance, ControlPlane
• Painless Multi-Cloud to the Edge Powered by NATS & Kubernetes - Tomasz Pietrek & David Gee, Synadia
• Demystifing IPv6 Kubernetes - Antonio Jose Ojea Garcia, Google & Fernando Gont, Yalo
• Open Policy Agent. (OPA) Intro & Deep Dive - Charlie Egan, Styra, Inc. (Couldn t really attend, room full)
• Practical Challenges with Pod Security Admission - V K rbes & Christian Schlotter, VMware
• Enabling HPC and ML Workloads with the Latest Kubernetes Job Features - Micha Wo niak, Google & Vanessa Sochat, Lawrence Livermore National Laboratory
• Can You Keep a Secret? on Secret Management in Kubernetes - Liav Yona & Gal Cohen, Firefly

The videos have been published on Youtube.

In a previous blog post I described the use of virtual postings to track accidental personal/family expenses. I've always been uncomfortable with that, and in hledger 1yr I outlined a potential scheme for finally addressing the virtual posting problem. separate journals My outline built on top of continuing to maintain both personal and family financial data in the same place, but I've decided that this can't work, because the different "directions" (or signs) of accidental transactions originating from either the family or personal side can't be addressed with any kind of alternate view on the same data. To illustrate with an example. A negative balance in family:liabilities:jon means "family owes jon". A coffee bought by mistake on the family credit card will have a negative posting on the credit card, and thus a positive one on the liabilities account. ("jon owes family"). That's fine. But what about when I buy family stuff on a personal card? The other side of of the transaction is also going to have a positive sign, so it can't be posted to family:liabilities:jon: it would have to go to somewhere else, like jon:liabilities:family. Now I have two accounts which track versions of the same thing, and they cannot be combined with a simple transaction since they're looking at the same value from opposite directions (and signs). Back when I first described the problem I was using a single journal file for all my transactions. After moving to lots of separate journal files (in hledger 1yr), it's become clearer to me that I don't need to maintain the Family and Personal data together, at all: they can be entirely separate journals. getting data between journals When I moved to a new set of ledger files for 2023, I needed to carry forward the balances from 2022 in the form of "opening balance" transactions. This was achieved by a report on the 2022 data, exported as CSV, and imported into the 2023 data (all following the scheme outlined by fully-fledged hledger.)) Separate Personal and Family journals need some information from each other, and I can achieve that in the same way as for opening balances: with an export of the relevant transactions as CSV, then imported on the other side. HLedger's CSV import system is flexible enough that we can effectively invert the sign of liabilities, addressing the problem above. Worked example We start with an accidental coffee purchased on the family card (and so this belongs to the Family ledger)

2022-08-20 coffee
    liabilities:creditcard             -3
    liabilities:jon:expenses:coffee     3

I've encoded the expense category that the Personal ledger will be interested in (the last bit, expenses:coffee) as a sub-account of the liabilities category that the Family ledger is interested in¹ (the first bit, liabilities:jon). When viewed on the Family side, the expense category is not interesting, and we can hide it with HLedger's alias feature²:

    alias /^liabilities:jon(.*)$/ = liabilities:jon

It then looks like this from the Family side:

2022-08-20 coffee
    liabilities:creditcard             -3
    liabilities:jon                     3

This transaction (and others like it) are exported via

hledger reg -f family/2023-back.journal liabilities:jon: -O csv \
        jon/import/family/liabilities.csv

(The trailing colon on liabilities:jon: is important here!) In the resulting CSV file, the running example transaction looks like

"55","2022-08-20","","coffee","liabilities:jon:expenses:coffee","  3.00","  3.00"

This is then converted into a journal file by hledger import. The rules file for the import is very simple: the fields date, description, account1 and amount are taken as-is; account2 is hard-coded to liabilities:family. The resulting transaction looks like

2022-08-20 coffee
    liabilities:jon:expenses:coffee     3
    liabilities:family                 -3

Before this journal is included by the main one, we have to adjust the expense account, to remove the liabilities:jon: prefix. The import rules can't do this³ , so we use another journal file as a go-between with another alias rule:

    alias /^liabilities.jon:/ =

This results, finally, in the following transaction in the Personal ledger:

2022-08-20 coffee
    expenses:coffee                     3
    liabilities:family                 -3

avoiding double-counting There's one set of transactions that we don't want to export across this divide, and that's because they're already there: any time I transfer money from myself to the family accounts (or vice versa) to address the accrued debt, the transaction is visible from both my family and personal statements. To avoid exporting these and double-counting them, I make sure those transactions don't post to an account matching the pattern used in the hledger reg report. That's what the trailing colon is for: It ensures I only export transactions which are to a sub-account of liabilities:jon, and not to the root account liabilities:jon itself: which is where I put the repayment transactions. I could instead use a more explicit sub-account like liabilities:jon:repayments or similar, since the trailing colon is quite subtle, but this works for me. Wrap up I've been really on the fence as to whether the complexity of this scheme is worth it to avoid the virtual postings. The previous scheme was much simpler. I have definitely made some mistakes with it, which didn't get caught by the double-entry rules that virtual postings ignore, but they're for small sums of money anyway. On the other hand, a lot of the "machinery" of this already existed for getting opening balances between calendar years, and the gory details are written down and hidden inside the Makefile. I also expect that I will continue to see advantages in having Family and Personal entirely separate, as they can each develop and adapt to their own needs without having to consider the other side of things every time. It's a running experiment, and time will tell if it's a good idea.

As suggested in my initial announcement of apt-sigstore my plan was to look into stronger uses of Sigstore than rekor, and I m now happy to announce that the apt-cosign plugin has been added to apt-sigstore and the operational project debdistcanary is publishing cosign-statements about the InRelease file published by the following distributions: Trisquel GNU/Linux, PureOS, Gnuinos, Ubuntu, Debian and Devuan. Summarizing the commands that you need to run as root to experience the great new world:

# run everything as root: su / sudo -i / doas -s
apt-get install -y apt gpg bsdutils wget
wget -nv -O/usr/local/bin/apt-verify-gpgv https://gitlab.com/debdistutils/apt-verify/-/raw/main/apt-verify-gpgv
chmod +x /usr/local/bin/apt-verify-gpgv
mkdir -p /etc/apt/verify.d
ln -s /usr/bin/gpgv /etc/apt/verify.d
echo 'APT::Key::gpgvcommand "apt-verify-gpgv";' > /etc/apt/apt.conf.d/75verify
wget -O/usr/local/bin/cosign https://github.com/sigstore/cosign/releases/download/v2.0.1/cosign-linux-amd64
echo 924754b2e62f25683e3e74f90aa5e166944a0f0cf75b4196ee76cb2f487dd980  /usr/local/bin/cosign   sha256sum -c
chmod +x /usr/local/bin/cosign
wget -nv -O/etc/apt/verify.d/apt-cosign https://gitlab.com/debdistutils/apt-sigstore/-/raw/main/apt-cosign
chmod +x /etc/apt/verify.d/apt-cosign
mkdir -p /etc/apt/trusted.cosign.d
dist=$(lsb_release --short --id   tr A-Z a-z)
wget -O/etc/apt/trusted.cosign.d/cosign-public-key-$dist.txt "https://gitlab.com/debdistutils/debdistcanary/-/raw/main/cosign/cosign-public-key-$dist.txt"
echo "Cosign::Base-URL \"https://gitlab.com/debdistutils/canary/$dist/-/raw/main/cosign\";" > /etc/apt/apt.conf.d/77cosign

Then run your usual apt-get update and look in the syslog to debug things. This is the kind of work that gets done while waiting for the build machines to attempt to reproducibly build PureOS. Unfortunately, the results is that a meager 16% of the 765 added/modifed packages are reproducible by me. There is some infrastructure work to be done to improve things: we should use sbuild for example. The build infrastructure should produce signed statements for each package it builds: One statement saying that it attempted to reproducible build a particular binary package (thus generated some build logs and diffoscope-output for auditing), and one statements saying that it actually was able to reproduce a package. Verifying such claims during apt-get install or possibly dpkg -i is a logical next step. There is some code cleanups and release work to be done now. Which distribution will be the first apt-based distribution that includes native support for Sigstore? Let s see. Sigstore is not the only relevant transparency log around, and I ve been trying to learn a bit about Sigsum to be able to support it as well. The more improved confidence about system security, the merrier!

Probably everyone is familiar with a regular VPN. The traditional use case is to connect to a corporate or home network from a remote location, and access services as if you were there. But these days, the notion of corporate network and home network are less based around physical location. For instance, a company may have no particular office at all, may have a number of offices plus a number of people working remotely, and so forth. A home network might have, say, a PVR and file server, while highly portable devices such as laptops, tablets, and phones may want to talk to each other regardless of location. For instance, a family member might be traveling with a laptop, another at a coffee shop, and those two devices might want to communicate, in addition to talking to the devices at home. And, in both scenarios, there might be questions about giving limited access to friends. Perhaps you d like to give a friend access to part of your file server, or as a company, you might have contractors working on a limited project. Pretty soon you wind up with a mess of VPNs, forwarded ports, and tricks to make it all work. With the increasing prevalence of CGNAT, a lot of times you can t even open a port to the public Internet. Each application or device probably has its own gateway just to make it visible on the Internet, some of which you pay for. Then you add on the question of: should you really trust your LAN anyhow? With possibilities of guests using it, rogue access points, etc., the answer is probably no . We can move the responsibility for dealing with NAT, fluctuating IPs, encryption, and authentication, from the application layer further down into the network stack. We then arrive at a much simpler picture for all. So this page is fundamentally about making the network work, simply and effectively.

How do we make the Internet work in these scenarios? We re going to combine three concepts:

1. A VPN, providing fully encrypted and authenticated communication and stable IPs
2. Mesh Networking, in which devices automatically discover optimal paths to reach each other
3. Zero-trust networking, in which we do not need to trust anything about the underlying LAN, because all our traffic uses the secure systems in points 1 and 2.

By combining these concepts, we arrive at some nice results:

• You can ssh hostname, where hostname is one of your machines (server, laptop, whatever), and as long as hostname is up, you can reach it, wherever it is, wherever you are.
  • Combined with mosh, these sessions will be durable even across moving to other host networks.
  • You could just as well use telnet, because the underlying network should be secure.
• You don t have to mess with encryption keys, certs, etc., for every internal-only service. Since IPs are now trustworthy, that s all you need. hosts.allow could make a comeback!
• You have a way of transiting out of extremely restrictive networks. Every tool discussed here has a way of falling back on routing things via a broker (relay) on TCP port 443 if all else fails.

There might sometimes be tradeoffs. For instance:

• On LANs faster than 1Gbps, performance may degrade due to encryption and encapsulation overhead. However, these tools should let hosts discover the locality of each other and not send traffic over the Internet if the devices are local.
• With some of these tools, hosts local to each other (on the same LAN) may be unable to find each other if they can t reach the control plane over the Internet (Internet is down or provider is down)

Some other features that some of the tools provide include:

• Easy sharing of limited access with friends/guests
• Taking care of everything you need, including SSL certs, for exposing a certain on-net service to the public Internet
• Optional routing of your outbound Internet traffic via an exit node on your network. Useful, for instance, if your local network is blocking tons of stuff.

Let s dive in.

Types of Mesh VPNs I ll go over several types of meshes in this article:

1. Fully decentralized with automatic hop routing This model has no special central control plane. Nodes discover each other in various ways, and establish routes to each other. These routes can be direct connections over the Internet, or via other nodes. This approach offers the greatest resilience. Examples I ll cover include Yggdrasil and tinc.
2. Automatic peer-to-peer with centralized control In this model, nodes, by default, communicate by establishing direct links between them. A regular node never carries traffic on behalf of other nodes. Special-purpose relays are used to handle cases in which NAT traversal is impossible. This approach tends to offer simple setup. Examples I ll cover include Tailscale, Zerotier, Nebula, and Netmaker.
3. Roll your own and hybrid approaches This is a grab bag of other ideas; for instance, running Yggdrasil over Tailscale.

Terminology For the sake of consistency, I m going to use common language to discuss things that have different terms in different ecosystems:

• Every tool discussed here has a way of dealing with NAT traversal. It may assist with establishing direct connections (eg, STUN), and if that fails, it may simply relay traffic between nodes. I ll call such a relay a broker . This may or may not be the same system that is a control plane for a tool.
• All of these systems operate over lower layers that are unencrypted. Those lower layers may be a LAN (wired or wireless, which may or may not have Internet access), or the public Internet (IPv4 and/or IPv6). I m going to call the unencrypted lower layer, whatever it is, the clearnet .

Evaluation Criteria Here are the things I want to see from a solution:

• Secure, with all communications end-to-end encrypted and authenticated, and prevention of traffic from untrusted devices.
• Flexible, adapting to changes in network topology quickly and automatically.
• Resilient, without single points of failure, and with devices local to each other able to communicate even if cut off from the Internet or other parts of the network.
• Private, minimizing leakage of information or metadata about me and my systems
• Able to traverse CGNAT without having to use a broker whenever possible
• A lesser requirement for me, but still a nice to have, is the ability to include others via something like Internet publishing or inviting guests.
• Fully or nearly fully Open Source
• Free or very cheap for personal use
• Wide operating system support, including headless Linux on x86_64 and ARM.

Fully Decentralized VPNs with Automatic Hop Routing Two systems fit this description: Yggdrasil and Tinc. Let s dive in.

Yggdrasil I ll start with Yggdrasil because I ve written so much about it already. It featured in prior posts such as:

• Make the Internet Yours Again With an Instant Mesh Network, which described the tyranny of IP rigidity and using Yggdrasil as a global mesh overlay.
• Using Yggdrasil As an Automatic Mesh Fabric to Connect All Your Docker Containers, VMs, and Servers is, in a significant sense, a more specific implementation of the ideas contained here; it s a private Yggdrasil mesh providing the communications layer for dispersed Docker containers.
• Recovering Our Lost Free Will Online: Tools and Techniques That Are Available Now features Yggdrasil.

Yggdrasil can be a private mesh VPN, or something more Yggdrasil can be a private mesh VPN, just like the other tools covered here. It s unique, however, in that a key goal of the project is to also make it useful as a planet-scale global mesh network. As such, Yggdrasil is a testbed of new ideas in distributed routing designed to scale up to massive sizes and all sorts of connection conditions. As of 2023-04-10, the main global Yggdrasil mesh has over 5000 nodes in it. You can choose whether or not to participate. Every node in a Yggdrasil mesh has a public/private keypair. Each node then has an IPv6 address (in a private address space) derived from its public key. Using these IPv6 addresses, you can communicate right away. Yggdrasil differs from most of the other tools here in that it does not necessarily seek to establish a direct link on the clearnet between, say, host A and host G for them to communicate. It will prefer such a direct link if it exists, but it is perfectly happy if it doesn t. The reason is that every Yggdrasil node is also a router in the Yggdrasil mesh. Let s sit with that concept for a moment. Consider:

• If you have a bunch of machines on your LAN, but only one of them can peer over the clearnet, that s fine; all the other machines will discover this route to the world and use it when necessary.
• All you need to run a broker is just a regular node with a public IP address. If you are participating in the global mesh, you can use one (or more) of the free public peers for this purpose.
• It is not necessary for every node to know about the clearnet IP address of every other node (improving privacy). In fact, it s not even necessary for every node to know about the existence of all the other nodes, so long as it can find a route to a given node when it s asked to.
• Yggdrasil can find one or more routes between nodes, and it can use this knowledge of multiple routes to aggressively optimize for varying network conditions, including combinations of, say, downloads and low-latency ssh sessions.

Behind the scenes, Yggdrasil calculates optimal routes between nodes as necessary, using a mesh-wide DHT for initial contact and then deriving more optimal paths. (You can also read more details about the routing algorithm.) One final way that Yggdrasil is different from most of the other tools is that there is no separate control server. No node is special , in charge, the sole keeper of metadata, or anything like that. The entire system is completely distributed and auto-assembling.

Meeting neighbors There are two ways that Yggdrasil knows about peers:

• By broadcast discovery on the local LAN
• By listening on a specific port (or being told to connect to a specific host/port)

Sometimes this might lead to multiple ways to connect to a node; Yggdrasil prefers the connection auto-discovered by broadcast first, then the lowest-latency of the defined path. In other words, when your laptops are in the same room as each other on your local LAN, your packets will flow directly between them without traversing the Internet.

Unique uses Yggdrasil is uniquely suited to network-challenged situations. As an example, in a post-disaster situation, Internet access may be unavailable or flaky, yet there may be many local devices perhaps ones that had never known of each other before that could share information. Yggdrasil meets this situation perfectly. The combination of broadcast auto-detection, distributed routing, and so forth, basically means that if there is any physical path between two nodes, Yggdrasil will find and enable it. Ad-hoc wifi is rarely used because it is a real pain. Yggdrasil actually makes it useful! Its broadcast discovery doesn t require any IP address provisioned on the interface at all (it just uses the IPv6 link-local address), so you don t need to figure out a DHCP server or some such. And, Yggdrasil will tend to perform routing along the contours of the RF path. So you could have a laptop in the middle of a long distance relaying communications from people farther out, because it could see both. Or even a chain of such things.

Yggdrasil: Security and Privacy Yggdrasil s mesh is aggressively greedy. It will peer with any node it can find (unless told otherwise) and will find a route to anywhere it can. There are two main ways to make sure you keep unauthorized traffic out: by restricting who can talk to your mesh, and by firewalling the Yggdrasil interface. Both can be used, and they can be used simultaneously. I ll discuss firewalling more at the end of this article. Basically, you ll almost certainly want to do this if you participate in the public mesh, because doing so is akin to having a globally-routable public IP address direct to your device. If you want to restrict who can talk to your mesh, you just disable the broadcast feature on all your nodes (empty MulticastInterfaces section in the config), and avoid telling any of your nodes to connect to a public peer. You can set a list of authorized public keys that can connect to your nodes listening interfaces, which you ll probably want to do. You will probably want to either open up some inbound ports (if you can) or set up a node with a known clearnet IP on a place like a $5/mo VPS to help with NAT traversal (again, setting AllowedPublicKeys as appropriate). Yggdrasil doesn t allow filtering multicast clients by public key, only by network interface, so that s why we disable broadcast discovery. You can easily enough teach Yggdrasil about static internal LAN IPs of your nodes and have things work that way. (Or, set up an internal gateway node or two, that the clients just connect to when they re local). But fundamentally, you need to put a bit more thought into this with Yggdrasil than with the other tools here, which are closed-only. Compared to some of the other tools here, Yggdrasil is better about information leakage; nodes only know details, such as clearnet IPs, of directly-connected peers. You can obtain the list of directly-connected peers of any known node in the mesh but that list is the public keys of the directly-connected peers, not the clearnet IPs. Some of the other tools contain a limited integrated firewall of sorts (with limited ACLs and such). Yggdrasil does not, but is fully compatible with on-host firewalls. I recommend these anyway even with many other tools.

Yggdrasil: Connectivity and NAT traversal Compared to the other tools, Yggdrasil is an interesting mix. It provides a fully functional mesh and facilitates connectivity in situations in which no other tool can. Yet its NAT traversal, while it exists and does work, results in using a broker under some of the more challenging CGNAT situations more often than some of the other tools, which can impede performance. Yggdrasil s underlying protocol is TCP-based. Before you run away screaming that it must be slow and unreliable like OpenVPN over TCP it s not, and it is even surprisingly good around bufferbloat. I ve found its performance to be on par with the other tools here, and it works as well as I d expect even on flaky 4G links. Overall, the NAT traversal story is mixed. On the one hand, you can run a node that listens on port 443 and Yggdrasil can even make it speak TLS (even though that s unnecessary from a security standpoint), so you can likely get out of most restrictive firewalls you will ever encounter. If you join the public mesh, know that plenty of public peers do listen on port 443 (and other well-known ports like 53, plus random high-numbered ones). If you connect your system to multiple public peers, there is a chance though a very small one that some public transit traffic might be routed via it. In practice, public peers hopefully are already peered with each other, preventing this from happening (you can verify this with yggdrasilctl debug_remotegetpeers key=ABC...). I have never experienced a problem with this. Also, since latency is a factor in routing for Yggdrasil, it is highly unlikely that random connections we use are going to be competitive with datacenter peers.

Yggdrasil: Sharing with friends If you re open to participating in the public mesh, this is one of the easiest things of all. Have your friend install Yggdrasil, point them to a public peer, give them your Yggdrasil IP, and that s it. (Well, presumably you also open up your firewall you did follow my advice to set one up, right?) If your friend is visiting at your location, they can just hop on your wifi, install Yggdrasil, and it will automatically discover a route to you. Yggdrasil even has a zero-config mode for ephemeral nodes such as certain Docker containers. Yggdrasil doesn t directly support publishing to the clearnet, but it is certainly possible to proxy (or even NAT) to/from the clearnet, and people do.

Yggdrasil: DNS There is no particular extra DNS in Yggdrasil. You can, of course, run a DNS server within Yggdrasil, just as you can anywhere else. Personally I just add relevant hosts to /etc/hosts and leave it at that, but it s up to you.

Yggdrasil: Source code, pricing, and portability Yggdrasil is fully open source (LGPLv3 plus additional permissions in an exception) and highly portable. It is written in Go, and has prebuilt binaries for all major platforms (including a Debian package which I made). There is no charge for anything with Yggdrasil. Listed public peers are free and run by volunteers. You can run your own peers if you like; they can be public and unlisted, public and listed (just submit a PR to get it listed), or private (accepting connections only from certain nodes keys). A peer in this case is just a node with a known clearnet IP address. Yggdrasil encourages use in other projects. For instance, NNCP integrates a Yggdrasil node for easy communication with other NNCP nodes.

Yggdrasil conclusions Yggdrasil is tops in reliability (having no single point of failure) and flexibility. It will maintain opportunistic connections between peers even if the Internet is down. The unique added feature of being able to be part of a global mesh is a nice one. The tradeoffs include being more prone to need to use a broker in restrictive CGNAT environments. Some other tools have clients that override the OS DNS resolver to also provide resolution of hostnames of member nodes; Yggdrasil doesn t, though you can certainly run your own DNS infrastructure over Yggdrasil (or, for that matter, let public DNS servers provide Yggdrasil answers if you wish). There is also a need to pay more attention to firewalling or maintaining separation from the public mesh. However, as I explain below, many other options have potential impacts if the control plane, or your account for it, are compromised, meaning you ought to firewall those, too. Still, it may be a more immediate concern with Yggdrasil. Although Yggdrasil is listed as experimental, I have been using it for over a year and have found it to be rock-solid. They did change how mesh IPs were calculated when moving from 0.3 to 0.4, causing a global renumbering, so just be aware that this is a possibility while it is experimental.

tinc tinc is the oldest tool on this list; version 1.0 came out in 2003! You can think of tinc as something akin to an older Yggdrasil without the public option. I will be discussing tinc 1.0.36, the latest stable version, which came out in 2019. The development branch, 1.1, has been going since 2011 and had its latest release in 2021. The last commit to the Github repo was in June 2022. Tinc is the only tool here to support both tun and tap style interfaces. I go into the difference more in the Zerotier review below. Tinc actually provides a better tap implementation than Zerotier, with various sane options for broadcasts, but I still think the call for an Ethernet, as opposed to IP, VPN is small. To configure tinc, you generate a per-host configuration and then distribute it to every tinc node. It contains a host s public key. Therefore, adding a host to the mesh means distributing its key everywhere; de-authorizing it means removing its key everywhere. This makes it rather unwieldy. tinc can do LAN broadcast discovery and mesh routing, but generally speaking you must manually teach it where to connect initially. Somewhat confusingly, the examples all mention listing a public address for a node. This doesn t make sense for a laptop, and I suspect you d just omit it. I think that address is used for something akin to a Yggdrasil peer with a clearnet IP. Unlike all of the other tools described here, tinc has no tool to inspect the running state of the mesh. Some of the properties of tinc made it clear I was unlikely to adopt it, so this review wasn t as thorough as that of Yggdrasil.

tinc: Security and Privacy As mentioned above, every host in the tinc mesh is authenticated based on its public key. However, to be more precise, this key is validated only at the point it connects to its next hop peer. (To be sure, this is also the same as how the list of allowed pubkeys works in Yggdrasil.) Since IPs in tinc are not derived from their key, and any host can assign itself whatever mesh IP it likes, this implies that a compromised host could impersonate another. It is unclear whether packets are end-to-end encrypted when using a tinc node as a router. The fact that they can be routed at the kernel level by the tun interface implies that they may not be.

tinc: Connectivity and NAT traversal I was unable to find much information about NAT traversal in tinc, other than that it does support it. tinc can run over UDP or TCP and auto-detects which to use, preferring UDP.

tinc: Sharing with friends tinc has no special support for this, and the difficulty of configuration makes it unlikely you d do this with tinc.

tinc: Source code, pricing, and portability tinc is fully open source (GPLv2). It is written in C and generally portable. It supports some very old operating systems. Mobile support is iffy. tinc does not seem to be very actively maintained.

tinc conclusions I haven t mentioned performance in my other reviews (see the section at the end of this post). But, it is so poor as to only run about 300Mbps on my 2.5Gbps network. That s 1/3 the speed of Yggdrasil or Tailscale. Combine that with the unwieldiness of adding hosts and some uncertainties in security, and I m not going to be using tinc.

Automatic Peer-to-Peer Mesh VPNs with centralized control These tend to be the options that are frequently discussed. Let s talk about the options.

Tailscale Tailscale is a popular choice in this type of VPN. To use Tailscale, you first sign up on tailscale.com. Then, you install the tailscale client on each machine. On first run, it prints a URL for you to click on to authorize the client to your mesh ( tailnet ). Tailscale assigns a mesh IP to each system. The Tailscale client lets the Tailscale control plane gather IP information about each node, including all detectable public and private clearnet IPs. When you attempt to contact a node via Tailscale, the client will fetch the known contact information from the control plane and attempt to establish a link. If it can contact over the local LAN, it will (it doesn t have broadcast autodetection like Yggdrasil; the information must come from the control plane). Otherwise, it will try various NAT traversal options. If all else fails, it will use a broker to relay traffic; Tailscale calls a broker a DERP relay server. Unlike Yggdrasil, a Tailscale node never relays traffic for another; all connections are either direct P2P or via a broker. Tailscale, like several others, is based around Wireguard; though wireguard-go rather than the in-kernel Wireguard. Tailscale has a number of somewhat unique features in this space:

• Funnel, which lets you expose ports on your system to the public Internet via the VPN.
• Exit nodes, which automate the process of routing your public Internet traffic over some other node in the network. This is possible with every tool mentioned here, but Tailscale makes switching it on or off a couple of quick commands away.
• Node sharing, which lets you share a subset of your network with guests
• A fantastic set of documentation, easily the best of the bunch.

Funnel, in particular, is interesting. With a couple of tailscale serve -style commands, you can expose a directory tree (or a development webserver) to the world. Tailscale gives you a public hostname, obtains a cert for it, and proxies inbound traffic to you. This is subject to some unspecified bandwidth limits, and you can only choose from three public ports, so it s not really a production solution but as a quick and easy way to demonstrate something cool to a friend, it s a neat feature.

Tailscale: Security and Privacy With Tailscale, as with the other tools in this category, one of the main threats to consider is the control plane. What are the consequences of a compromise of Tailscale s control plane, or of the credentials you use to access it? Let s begin with the credentials used to access it. Tailscale operates no identity system itself, instead relying on third parties. For individuals, this means Google, Github, or Microsoft accounts; Okta and other SAML and similar identity providers are also supported, but this runs into complexity and expense that most individuals aren t wanting to take on. Unfortunately, all three of those types of accounts often have saved auth tokens in a browser. Personally I would rather have a separate, very secure, login. If a person does compromise your account or the Tailscale servers themselves, they can t directly eavesdrop on your traffic because it is end-to-end encrypted. However, assuming an attacker obtains access to your account, they could:

• Tamper with your Tailscale ACLs, permitting new actions
• Add new nodes to the network
• Forcibly remove nodes from the network
• Enable or disable optional features

Of note is that they cannot just commandeer an existing IP. I would say the riskiest possibility here is that could add new nodes to the mesh. Because they could also tamper with your ACLs, they could then proceed to attempt to access all your internal services. They could even turn on service collection and have Tailscale tell them what and where all the services are. Therefore, as with other tools, I recommend a local firewall on each machine with Tailscale. More on that below. Tailscale has a new alpha feature called tailnet lock which helps with this problem. It requires existing nodes in the mesh to sign a request for a new node to join. Although this doesn t address ACL tampering and some of the other things, it does represent a significant help with the most significant concern. However, tailnet lock is in alpha, only available on the Enterprise plan, and has a waitlist, so I have been unable to test it. Any Tailscale node can request the IP addresses belonging to any other Tailscale node. The Tailscale control plane captures, and exposes to you, this information about every node in your network: the OS hostname, IP addresses and port numbers, operating system, creation date, last seen timestamp, and NAT traversal parameters. You can optionally enable service data capture as well, which sends data about open ports on each node to the control plane. Tailscale likes to highlight their key expiry and rotation feature. By default, all keys expire after 180 days, and traffic to and from the expired node will be interrupted until they are renewed (basically, you re-login with your provider and do a renew operation). Unfortunately, the only mention I can see of warning of impeding expiration is in the Windows client, and even there you need to edit a registry key to get the warning more than the default 24 hours in advance. In short, it seems likely to cut off communications when it s most important. You can disable key expiry on a per-node basis in the admin console web interface, and I mostly do, due to not wanting to lose connectivity at an inopportune time.

Tailscale: Connectivity and NAT traversal When thinking about reliability, the primary consideration here is being able to reach the Tailscale control plane. While it is possible in limited circumstances to reach nodes without the Tailscale control plane, it is a fairly brittle setup and notably will not survive a client restart. So if you use Tailscale to reach other nodes on your LAN, that won t work unless your Internet is up and the control plane is reachable. Assuming your Internet is up and Tailscale s infrastructure is up, there is little to be concerned with. Your own comfort level with cloud providers and your Internet should guide you here. Tailscale wrote a fantastic article about NAT traversal and they, predictably, do very well with it. Tailscale prefers UDP but falls back to TCP if needed. Broker (DERP) servers step in as a last resort, and Tailscale clients automatically select the best ones. I m not aware of anything that is more successful with NAT traversal than Tailscale. This maximizes the situations in which a direct P2P connection can be used without a broker. I have found Tailscale to be a bit slow to notice changes in network topography compared to Yggdrasil, and sometimes needs a kick in the form of restarting the client process to re-establish communications after a network change. However, it s possible (maybe even probable) that if I d waited a bit longer, it would have sorted this all out.

Tailscale: Sharing with friends I touched on the funnel feature earlier. The sharing feature lets you give an invite to an outsider. By default, a person accepting a share can make only outgoing connections to the network they re invited to, and cannot receive incoming connections from that network this makes sense. When sharing an exit node, you get a checkbox that lets you share access to the exit node as well. Of course, the person accepting the share needs to install the Tailnet client. The combination of funnel and sharing make Tailscale the best for ad-hoc sharing.

Tailscale: DNS Tailscale s DNS is called MagicDNS. It runs as a layer atop your standard DNS taking over /etc/resolv.conf on Linux and provides resolution of mesh hostnames and some other features. This is a concept that is pretty slick. It also is a bit flaky on Linux; dueling programs want to write to /etc/resolv.conf. I can t really say this is entirely Tailscale s fault; they document the problem and some workarounds. I would love to be able to add custom records to this service; for instance, to override the public IP for a service to use the in-mesh IP. Unfortunately, that s not yet possible. However, MagicDNS can query existing nameservers for certain domains in a split DNS setup.

Tailscale: Source code, pricing, and portability Tailscale is almost fully open source and the client is highly portable. The client is open source (BSD 3-clause) on open source platforms, and closed source on closed source platforms. The DERP servers are open source. The coordination server is closed source, although there is an open source coordination server called Headscale (also BSD 3-clause) made available with Tailscale s blessing and informal support. It supports most, but not all, features in the Tailscale coordination server. Tailscale s pricing (which does not apply when using Headscale) provides a free plan for 1 user with up to 20 devices. A Personal Pro plan expands that to 100 devices for $48 per year - not a bad deal at $4/mo. A Community on Github plan also exists, and then there are more business-oriented plans as well. See the pricing page for details. As a small note, I appreciated Tailscale s install script. It properly added Tailscale s apt key in a way that it can only be used to authenticate the Tailscale repo, rather than as a systemwide authenticator. This is a nice touch and speaks well of their developers.

Tailscale conclusions Tailscale is tops in sharing and has a broad feature set and excellent documentation. Like other solutions with a centralized control plane, device communications can stop working if the control plane is unreachable, and the threat model of the control plane should be carefully considered.

Zerotier Zerotier is a close competitor to Tailscale, and is similar to it in a lot of ways. So rather than duplicate all of the Tailscale information here, I m mainly going to describe how it differs from Tailscale. The primary difference between the two is that Zerotier emulates an Ethernet network via a Linux tap interface, while Tailscale emulates a TCP/IP network via a Linux tun interface. However, Zerotier has a number of things that make it be a somewhat imperfect Ethernet emulator. For one, it has a problem with broadcast amplification; the machine sending the broadcast sends it to all the other nodes that should receive it (up to a set maximum). I wouldn t want to have a lot of programs broadcasting on a slow link. While in theory this could let you run Netware or DECNet across Zerotier, I m not really convinced there s much call for that these days, and Zerotier is clearly IP-focused as it allocates IP addresses and such anyhow. Zerotier provides special support for emulated ARP (IPv4) and NDP (IPv6). While you could theoretically run Zerotier as a bridge, this eliminates the zero trust principle, and Tailscale supports subnet routers, which provide much of the same feature set anyhow. A somewhat obscure feature, but possibly useful, is Zerotier s built-in support for multipath WAN for the public interface. This actually lets you do a somewhat basic kind of channel bonding for WAN.

Zerotier: Security and Privacy The picture here is similar to Tailscale, with the difference that you can create a Zerotier-local account rather than relying on cloud authentication. I was unable to find as much detail about Zerotier as I could about Tailscale - notably I couldn t find anything about how sticky an IP address is. However, the configuration screen lets me delete a node and assign additional arbitrary IPs within a subnet to other nodes, so I think the assumption here is that if your Zerotier account (or the Zerotier control plane) is compromised, an attacker could remove a legit device, add a malicious one, and assign the previous IP of the legit device to the malicious one. I m not sure how to mitigate against that risk, as firewalling specific IPs is ineffective if an attacker can simply take them over. Zerotier also lacks anything akin to Tailnet Lock. For this reason, I didn t proceed much further in my Zerotier evaluation.

Zerotier: Connectivity and NAT traversal Like Tailscale, Zerotier has NAT traversal with STUN. However, it looks like it s more limited than Tailscale s, and in particular is incompatible with double NAT that is often seen these days. Zerotier operates brokers ( root servers ) that can do relaying, including TCP relaying. So you should be able to connect even from hostile networks, but you are less likely to form a P2P connection than with Tailscale.

Zerotier: Sharing with friends I was unable to find any special features relating to this in the Zerotier documentation. Therefore, it would be at the same level as Yggdrasil: possible, maybe even not too difficult, but without any specific help.

Zerotier: DNS Unlike Tailscale, Zerotier does not support automatically adding DNS entries for your hosts. Therefore, your options are approximately the same as Yggdrasil, though with the added option of pushing configuration pointing to your own non-Zerotier DNS servers to the client.

Zerotier: Source code, pricing, and portability The client ZeroTier One is available on Github under a custom business source license which prevents you from using it in certain settings. This license would preclude it being included in Debian. Their library, libzt, is available under the same license. The pricing page mentions a community edition for self hosting, but the documentation is sparse and it was difficult to understand what its feature set really is. The free plan lets you have 1 user with up to 25 devices. Paid plans are also available.

Zerotier conclusions Frankly I don t see much reason to use Zerotier. The virtual Ethernet model seems to be a weird hybrid that doesn t bring much value. I m concerned about the implications of a compromise of a user account or the control plane, and it lacks a lot of Tailscale features (MagicDNS and sharing). The only thing it may offer in particular is multipath WAN, but that s esoteric enough and also solvable at other layers that it doesn t seem all that compelling to me. Add to that the strange license and, to me anyhow, I don t see much reason to bother with it.

Netmaker Netmaker is one of the projects that is making noise these days. Netmaker is the only one here that is a wrapper around in-kernel Wireguard, which can make a performance difference when talking to peers on a 1Gbps or faster link. Also, unlike other tools, it has an ingress gateway feature that lets people that don t have the Netmaker client, but do have Wireguard, participate in the VPN. I believe I also saw a reference somewhere to nodes as routers as with Yggdrasil, but I m failing to dig it up now. The project is in a bit of an early state; you can sign up for an upcoming closed beta with a SaaS host, but really you are generally pointed to self-hosting using the code in the github repo. There are community and enterprise editions, but it s not clear how to actually choose. The server has a bunch of components: binary, CoreDNS, database, and web server. It also requires elevated privileges on the host, in addition to a container engine. Contrast that to the single binary that some others provide. It looks like releases are frequent, but sometimes break things, and have a somewhat more laborious upgrade processes than most. I don t want to spend a lot of time managing my mesh. So because of the heavy needs of the server, the upgrades being labor-intensive, it taking over iptables and such on the server, I didn t proceed with a more in-depth evaluation of Netmaker. It has a lot of promise, but for me, it doesn t seem to be in a state that will meet my needs yet.

Nebula Nebula is an interesting mesh project that originated within Slack, seems to still be primarily sponsored by Slack, but is also being developed by Defined Networking (though their product looks early right now). Unlike the other tools in this section, Nebula doesn t have a web interface at all. Defined Networking looks likely to provide something of a SaaS service, but for now, you will need to run a broker ( lighthouse ) yourself; perhaps on a $5/mo VPS. Due to the poor firewall traversal properties, I didn t do a full evaluation of Nebula, but it still has a very interesting design.

Nebula: Security and Privacy Since Nebula lacks a traditional control plane, the root of trust in Nebula is a CA (certificate authority). The documentation gives this example of setting it up:

./nebula-cert sign -name "lighthouse1" -ip "192.168.100.1/24"
./nebula-cert sign -name "laptop" -ip "192.168.100.2/24" -groups "laptop,home,ssh"
./nebula-cert sign -name "server1" -ip "192.168.100.9/24" -groups "servers"
./nebula-cert sign -name "host3" -ip "192.168.100.10/24"

So the cert contains your IP, hostname, and group allocation. Each host in the mesh gets your CA certificate, and the per-host cert and key generated from each of these steps. This leads to a really nice security model. Your CA is the gatekeeper to what is trusted in your mesh. You can even have it airgapped or something to make it exceptionally difficult to breach the perimeter. Nebula contains an integrated firewall. Because the ability to keep out unwanted nodes is so strong, I would say this may be the one mesh VPN you might consider using without bothering with an additional on-host firewall. You can define static mappings from a Nebula mesh IP to a clearnet IP. I haven t found information on this, but theoretically if NAT traversal isn t required, these static mappings may allow Nebula nodes to reach each other even if Internet is down. I don t know if this is truly the case, however.

Nebula: Connectivity and NAT traversal This is a weak point of Nebula. Nebula sends all traffic over a single UDP port; there is no provision for using TCP. This is an issue at certain hotel and other public networks which open only TCP egress ports 80 and 443. I couldn t find a lot of detail on what Nebula s NAT traversal is capable of, but according to a certain Github issue, this has been a sore spot for years and isn t as capable as Tailscale. You can designate nodes in Nebula as brokers (relays). The concept is the same as Yggdrasil, but it s less versatile. You have to manually designate what relay to use. It s unclear to me what happens if different nodes designate different relays. Keep in mind that this always happens over a UDP port.

Nebula: Sharing with friends There is no particular support here.

Nebula: DNS Nebula has experimental DNS support. In contrast with Tailscale, which has an internal DNS server on every node, Nebula only runs a DNS server on a lighthouse. This means that it can t forward requests to a DNS server that s upstream for your laptop s particular current location. Actually, Nebula s DNS server doesn t forward at all. It also doesn t resolve its own name. The Nebula documentation makes reference to using multiple lighthouses, which you may want to do for DNS redundancy or performance, but it s unclear to me if this would make each lighthouse form a complete picture of the network.

Nebula: Source code, pricing, and portability Nebula is fully open source (MIT). It consists of a single Go binary and configuration. It is fairly portable.

Nebula conclusions I am attracted to Nebula s unique security model. I would probably be more seriously considering it if not for the lack of support for TCP and poor general NAT traversal properties. Its datacenter connectivity heritage does show through.

Roll your own and hybrid Here is a grab bag of ideas:

Running Yggdrasil over Tailscale One possibility would be to use Tailscale for its superior NAT traversal, then allow Yggdrasil to run over it. (You will need a firewall to prevent Tailscale from trying to run over Yggdrasil at the same time!) This creates a closed network with all the benefits of Yggdrasil, yet getting the NAT traversal from Tailscale. Drawbacks might be the overhead of the double encryption and double encapsulation. A good Yggdrasil peer may wind up being faster than this anyhow.

Public VPN provider for NAT traversal A public VPN provider such as Mullvad will often offer incoming port forwarding and nodes in many cities. This could be an attractive way to solve a bunch of NAT traversal problems: just use one of those services to get you an incoming port, and run whatever you like over that. Be aware that a number of public VPN clients have a kill switch to prevent any traffic from egressing without using the VPN; see, for instance, Mullvad s. You ll need to disable this if you are running a mesh atop it.

Other

Combining with local firewalls For most of these tools, I recommend using a local firewal in conjunction with them. I have been using firehol and find it to be quite nice. This means you don t have to trust the mesh, the control plane, or whatever. The catch is that you do need your mesh VPN to provide strong association between IP address and node. Most, but not all, do.

Performance I tested some of these for performance using iperf3 on a 2.5Gbps LAN. Here are the results. All speeds are in Mbps.

Tool	iperf3 (default)	iperf3 -P 10	iperf3 -R
Direct (no VPN)	2406	2406	2764
Wireguard (kernel)	1515	1566	2027
Yggdrasil	892	1126	1105
Tailscale	950	1034	1085
Tinc	296	300	277

You can see that Wireguard was significantly faster than the other options. Tailscale and Yggdrasil were roughly comparable, and Tinc was terrible.

IP collisions When you are communicating over a network such as these, you need to trust that the IP address you are communicating with belongs to the system you think it does. This protects against two malicious actor scenarios:

1. Someone compromises one machine on your mesh and reconfigures it to impersonate a more important one
2. Someone connects an unauthorized system to the mesh, taking over a trusted IP, and uses the privileges of the trusted IP to access resources

To summarize the state of play as highlighted in the reviews above:

• Yggdrasil derives IPv6 addresses from a public key
• tinc allows any node to set any IP
• Tailscale IPs aren t user-assignable, but the assignment algorithm is unknown
• Zerotier allows any IP to be allocated to any node at the control plane
• I don t know what Netmaker does
• Nebula IPs are baked into the cert and signed by the CA, but I haven t verified the enforcement algorithm

So this discussion really only applies to Yggdrasil and Tailscale. tinc and Zerotier lack detailed IP security, while Nebula expects IP allocations to be handled outside of the tool and baked into the certs (therefore enforcing rigidity at that level). So the question for Yggdrasil and Tailscale is: how easy is it to commandeer a trusted IP? Yggdrasil has a brief discussion of this. In short, Yggdrasil offers you both a dedicated IP and a rarely-used /64 prefix which you can delegate to other machines on your LAN. Obviously by taking the dedicated IP, a lot more bits are available for the hash of the node s public key, making collisions technically impractical, if not outright impossible. However, if you use the /64 prefix, a collision may be more possible. Yggdrasil s hashing algorithm includes some optimizations to make this more difficult. Yggdrasil includes a genkeys tool that uses more CPU cycles to generate keys that are maximally difficult to collide with. Tailscale doesn t document their IP assignment algorithm, but I think it is safe to say that the larger subnet you use, the better. If you try to use a /24 for your mesh, it is certainly conceivable that an attacker could remove your trusted node, then just manually add the 240 or so machines it would take to get that IP reassigned. It might be a good idea to use a purely IPv6 mesh with Tailscale to minimize this problem as well. So, I think the risk is low in the default configurations of both Yggdrasil and Tailscale (certainly lower than with tinc or Zerotier). You can drive the risk even lower with both.

Final thoughts For my own purposes, I suspect I will remain with Yggdrasil in some fashion. Maybe I will just take the small performance hit that using a relay node implies. Or perhaps I will get clever and use an incoming VPN port forward or go over Tailscale. Tailscale was the other option that seemed most interesting. However, living in a region with Internet that goes down more often than I d like, I would like to just be able to send as much traffic over a mesh as possible, trusting that if the LAN is up, the mesh is up. I have one thing that really benefits from performance in excess of Yggdrasil or Tailscale: NFS. That s between two machines that never leave my LAN, so I will probably just set up a direct Wireguard link between them. Heck of a lot easier than trying to do Kerberos! Finally, I wrote this intending to be useful. I dealt with a lot of complexity and under-documentation, so it s possible I got something wrong somewhere. Please let me know if you find any errors.

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This blog post is a copy of a page on my website. That page may be periodically updated.

The absolute number may not be impressive, but what I hope is at least a useful contribution is that there actually is a number on how much of Trisquel is reproducible. Hopefully this will inspire others to help improve the actual metric. tl;dr: go to reproduce-trisquel. When I set about to understand how Trisquel worked, I identified a number of things that would improve my confidence in it. The lowest hanging fruit for me was to manually audit the package archive, and I wrote a tool called debdistdiff to automate this for me. That led me to think about apt archive transparency more in general. I have made some further work in that area (hint: apt-verify) that deserve its own blog post eventually. Most of apt archive transparency is futile if we don t trust the intended packages that are in the archive. One way to measurable increase trust in the package are to provide reproducible builds of the packages, which should by now be an established best practice. Code review is still important, but since it will never provide positive guarantees we need other processes that can identify sub-optimal situations automatically. The way reproducible builds easily identify negative results is what I believe has driven much of its success: its results are tangible and measurable. The field of software engineering is in need of more such practices. The design of my setup to build Trisquel reproducible are as follows.

• The project debdistget is responsible for downloading Release/Packages files (which are the most relevant files from dists/) from apt archives, and works by commiting them into GitLab-hosted git-repositories. I maintain several such repositories for popular apt-archives, including for Trisquel and its upstream Ubuntu. GitLab invokes a schedule pipeline to do the downloading, and there is some race conditions here.
• The project debdistdiff is used to produce the list of added and modified packages, which are the input to actually being able to know what packages to reproduce. It publishes human readable summary of difference for several distributions, including Trisquel vs Ubuntu. Early on I decided that rebuilding all of the upstream Ubuntu packages is out of scope for me: my personal trust in the official Debian/Ubuntu apt archives are greater than my trust of the added/modified packages in Trisquel.
• The final project reproduce-trisquel puts the pieces together briefly as follows, everything being driven from its .gitlab-ci.yml file.
  • There is a (manually triggered) job generate-build-image to create a build image to speed up CI/CD runs, using a simple Dockerfile.
  • There is a (manually triggered) job generate-package-lists that uses debdistdiff to generate and store package lists and puts its output in lists/. The reason this is manually triggered right now is due to a race condition.
  • There is a (scheduled) job that does two things: from the package lists, the script generate-ci-packages.sh builds a GitLab CI/CD instruction file ci-packages.yml that describes jobs for each package to build. The second part is generate-readme.sh that re-generate the project s README.md based on the build logs and diffoscope outputs that stored in the git repository.
  • Through the ci-packages.yml file, there is a large number of jobs that are dynamically defined, which currently are manually triggered to not overload the build servers. The script build-package.sh is invoked and attempts to rebuild a package, and stores build log and diffoscope output in the git project itself.

I did not expect to be able to use the GitLab shared runners to do the building, however they turned out to work quite well and I postponed setting up my own runner. There is a manually curated lists/disabled-aramo.txt with some packages that all required too much disk space or took over two hours to build. Today I finally took the time to setup a GitLab runner using podman running Trisquel aramo, and I expect to complete builds of the remaining packages soon one of my Dell R630 server with 256GB RAM and dual 2680v4 CPUs should deliver sufficient performance. Current limitations and ideas on further work (most are filed as project issues) include:

• We don t support *.buildinfo files. As far as I am aware, Trisquel does not publish them for their builds. Improving this would be a first step forward, anyone able to help? Compare buildinfo.debian.net. For example, many packages differ only in their NT_GNU_BUILD_ID symbol inside the ELF binary, see example diffoscope output for libgpg-error. By poking around in jenkins.trisquel.org I managed to discover that Trisquel built initramfs-utils in the randomized path /build/initramfs-tools-bzRLUp and hard-coding that path allowed me to reproduce that package. I expect the same to hold for many other packages. Unfortunately, this failure turned into success with that package moved the needle from 42% reproducibility to 43% however I didn t let that stand in the way of a good headline.
• The mechanism to download the Release/Package-files from dists/ is not fool-proof: we may not capture all ever published such files. While this is less of a concern for reproducibility, it is more of a concern for apt transparency. Still, having Trisquel provide a service similar to snapshot.debian.org would help.
• Having at least one other CPU architecture would be nice.
• Due to lack of time and mental focus, handling incremental updates of new versions of packages is not yet working. This means we only ever build one version of a package, and never discover any newly published versions of the same package. Now that Trisquel aramo is released, the expected rate of new versions should be low, but still happens due to security or backports.
• Porting this to test supposedly FSDG-compliant distributions such as PureOS and Gnuinos should be relatively easy. I m also looking at Devuan because of Gnuinos.
• The elephant in the room is how reproducible Ubuntu is in the first place.

Happy Easter Hacking! Update 2023-04-17: The original project reproduce-trisquel that was announced here has been archived and replaced with two projects, one generic debdistreproduce and one with results for Trisquel: reproduce/trisquel .

Just some of the organisations that leaked data in 2022

It seems like just about every day there s another report of another company getting hacked and having its sensitive data (or, worse, the sensitive data of its customers) stolen. Sometimes, people s most intimate information gets dumped for the world to see. Other times it s just used for identity theft, extortion, and other crimes. In the least worst case, the attacker gets cold feet, but people suffer stress and inconvenience from having to replace identity documents. A great way to protect information from being leaked is to encrypt it. We encrypt data while it s being sent over the Internet (with TLS), and we encrypt it when it s at rest (with disk or volume encryption). Yet, everyone s data seems to still get stolen on a regular basis. Why? Because the data is kept online in an unencrypted form, sitting in the database while its being used. This means that attackers can just connect to the database, or trick the application into dumping the database, and all the data is just lying there, waiting to be misused.

It s Not the Devs Fault, Though You may be thinking that leaving an entire database full of sensitive data unencrypted seems like a terrible idea. And you re right: it is a terrible idea. But it s seemingly unavoidable. The problem is that in order to do what a database does best (query, sort, and aggregate data), it needs to be able to know what the data is. When you encrypt data, however, all the database sees is a locked box.

Not very useful for a database

The database can t tell what s in the locked box whether it s a number equal to 42, or a date that s less than 2023-01-01, or a string that contains the substring foo . Every value is just an opaque blob of stuff , and the database is rendered completely useless. Since modern applications usually rely pretty heavily on their database, it s essentially impossible to build an application if you ve turned your database into a glorified flat-file by encrypting everything in it. Thus, it s hardly surprising that developers have to leave the data laying around unencrypted, for anyone to come along and take.

Introducing Enquo I said before that having data unencrypted in a database is seemingly unavoidable. That s because there are some innovative cryptographic techniques that can make it possible to query encrypted data.

Indeed

The purpose of the Enquo project is to provide a common set of cryptographic primitives that implement ENcrypted QUery Operations (ie Enquo ), and integrate those operations into databases, ORMs, and anywhere else that could benefit. The end goal is to provide the ability to encrypt all the data stored in any database server, while still allowing the data to be queried and aggregated. So far, the project consists of these components:

• the enquo-core library, that implements queryable encrypted integers, dates, and text in Rust and Ruby;
• a PostgreSQL extension, pg_enquo, that allows PostgreSQL to query encrypted data; and
• a Rails ActiveRecord extension, ActiveEnquo, that augments ActiveRecord to do the encryption/decryption required.

Support for other languages and ORMs is designed to be as straightforward as possible, and integration with other databases is mostly dependent on their own extensibility. The project s core tenets emphasise both uncompromising security, and a friendly developer experience. Naturally, all Enquo code is open source, released under the MIT licence.

Would You Like To Know More?

Everyone who uses a database...

If all this sounds relevant to your interests:

1. If you use Ruby on Rails and PostgreSQL, you re halfway home already. Follow the ActiveEnquo getting started tutorial and see how much of your data Enquo can already protect. When you find data you want to encrypt but can t, tell me about it.
   • If you use Ruby and PostgreSQL with another ORM, such as Sequel, writing a plugin to support Enquo shouldn t be too difficult. The ActiveEnquo code should give you a good start. If you get stuck, get in touch.
2. If you use PostgreSQL with another programming language, tell me what language you use and we ll work together to get bindings for that library created.
3. If you use another database server, support is coming for your database of choice eventually, but at present there s no timeline on support. On the off chance that you happen to be a hard-core database hacking expert, and would like to work on getting Enquo support in your preferred database server, I d love to talk to you.