Search Results: "etbe"

28 March 2022

Russell Coker: Hangouts Replacement

Google is currently in the process of killing Hangouts. Last year Hangouts was quite a nice IM system with integrated video chat and voice calling. Now they have decided to kill it and replace it with Google Chat and Google Meet both of which are integrated with the Gmail app on Android. To start getting people off the old platform they have disabled video and audio chats with more than 2 people in Hangouts. To do a video call you have to use Meet which has a worse user interface and isn t integrated with text chat, so if in a text discussion someone says let s have a video call you have to open a new app. Meet also doesn t appear to have a facility to notify group members that someone has joined a group call so it s required that Chat (or something else) is used to tell people they can join Meet. Many of my relatives use Hangouts because they are forced to have it installed on their Android phones and because it worked quite well. Now it doesn t work well and will soon be going away. So another option is needed. I m considering Matrix as a replacement. Matrix has a good feature set and is being worked on a lot. The video conferencing is through a connection to a Jitsi server and is well integrated giving functionality more like Hangouts than Chat/Meet. For the LUV Matrix server the URL https://luv.asn.au/.well-known/matrix/client has the following contents:
 
  "m.homeserver":  
    "base_url": "https://luv.asn.au"
   
  "jitsi":  
    "preferredDomain": "jitsi.perthchat.org"
   
  "im.vector.riot.jitsi":  
    "preferredDomain": "jitsi.perthchat.org"
   
 
This specifies the Jitsi server to be used for chats started from that Matrix server. The PerthChat.org people seem to be leading the way for self hosted Matrix in Australia. Note that other people shouldn t link to their Jitsi server without discussing it with them first. I only included real data because it s published on the web so there s no point in keeping it secret. The Flounder free software users group [1] uses Matrix a lot. We will probably discuss Matrix at the next meeting on Saturday. There is also Element Call [2] which is apparently more integrated with Matrix (and also newer and possibly buggier). Jitsi works and we can change to a different service easily enough at a later time.

Russell Coker: Reading Glasses

About 4 years ago at a routine eye check the optometrist recommended that I get reading glasses. Apparently I m old enough that my eyes are losing their ability to focus at different distances to having different glasses for close and remote objects (EG reading and driving) is necessary for good vision. The optometrist asked me the distance that I use for reading and I indicated a distance that is good for books and phones (about 20cm). So I got a pair of glasses that worked well for that but didn t work well for the vast majority of my close work which is computer monitors. I found that I could use my reading glasses with my laptop when lying in bed if I had the laptop on my chest with the keyboard touching my chin, which is a reasonable position for watching TV but not for much else. About 2 years ago I had another eye check which determined that the glasses for long distance were good and got reading glasses designed for objects about 80cm away which worked well for monitors and were usable for watching TV. Recently I accidentally broke my newer pair of reading glasses and discovered that the older pair now works for distances of about a meter. So it appears that I have become significantly more long sighted over the last 4 years.

25 March 2022

Russell Coker: Wayland

The Wayland protocol [1] is designed to be more secure than X, when X was designed there wasn t much thought given to the possibility of programs with different access levels displaying on the same desktop. The Xephyr nested X server [2] is good for running an entire session from a remote untrusted host on a local display but isn t suitable for multiple applications in the same session. GNOME supported Wayland by default in Debian since the Bullseye release and for KDE support you can install the plasma-workspace-wayland which gives you an option for the session type of KDE Plasma Wayland when you login. For systems which don t use the KDE Plasma workspace but which have some KDE apps you should install the package qtwayland5 to allow the KDE apps to use the Wayland protocol. See the KDE page of the Debian Wiki [3] for more information. The Debian Wiki page on Wayland has more useful information [4]. Apparently you have to use gdm instead of sddm to get Wayland for the login prompt. To get screen sharing working on Wayland (and also to get a system that doesn t give out error messages) you need to install the pipewire package (see the Pipewire project page for more information [6]). Daniel Stone gave a great LCA talk about Wayland in 2013 [5]. I have just converted two of my systems to Wayland. It s pretty uneventful, things seem to work the same way as before. It might be theoretically faster but in practice Xorg was fast enough that there s not much possibility to appear faster. My aim is to work on Linux desktop security to try and get process isolation similar to what Android does on the PC desktop and on Debian based phones such as the Librem 5. Allowing some protection against graphics based attacks is only the first step towards that goal, but it s an important step. More blog posts on related topics will follow. Update: One thing I forgot to mention is that MAC systems need policy changes for Wayland. There are direct changes (allowing background daemons for GPU access to talk to a Wayland server running in a user context instead of an X server in a system context) and indirect changes (having the display server and window manager merged).

19 March 2022

Russell Coker: More About the Librem 5

I concluded my previous post about the Purism Librem 5 [1] with the phone working as a Debian/GNOME system with SSH access over the LAN. Before I published that post I managed to render it unbootable, making a new computer unbootable on the first day of owning it isn t uncommon for me. In this case I tried to get SE Linux running on it and changing the kernel commandline parameter security=apparmor to security=selinux caused it to fail the checksum on kernel parameters and halt the boot. That seems to require a fresh install, it seems possible that I could setup my Librem5 to boot a recovery image from a SD card in such situations but that doesn t seem to be well documented and I didn t have any important data to lose. If I do figure out how to recover data by booting from a micro SD card I ll document it. Here s the documentation for reflashing the phone [2], you have to use the --variant luks option for the flashing tool to have an encrypted root filesystem (should default to on to match the default shipping configuration). There is an option --skip-cleanup to allow you to use the same image multiple times, but that probably isn t useful. The image that is available for download today has the latest kernel update that I installed yesterday so it seems that they quickly update the image which makes it convenient to get the latest (dpkg is slow on low power ARM systems). Overall the flash tool is nicely written, does the download and install and instructs you how to get the phone in flashing mode. It is a minor annoyance that the battery has to be removed as part of the flashing process, I will probably end up flashing my phone more often than I want to take the back off the case. A mitigating factor is that the back is well designed and doesn t appear prone to having it s plastic tabs breaking off when removed (as has happened to several other phones I ve owned). The camera doesn t seem to work well at this time, all photos have an unusually low brightness. The audio recording also doesn t work well, speaking clearly into the phone results in quiet recordings. I updated the Debian Wiki page on Mobile devices [3] to include a link to a page about the Librem5 [4] and to also have a section about applications known to work well on mobile devices. Hopefully other people will make some additions to that as most programs in Debian don t work well on mobile devices so we need a list of known good applications as well as applications that can be easily changed to work well. One thing I ve started looking at is the code for the Geary MUA (the default MUA for the Librem5 and the only one in Debian I know to be suitable for a phone). It needs the Thunderbird style autoconfig and it needs the ability to select which IMAP folders to scan as a common practice is to have some large IMAP folders that aren t used on mobile devices. I believe that Android runs each app in a separate UID to prevent them from messing with each other. The configuration on a standard Linux system and on PureOS is to have all apps running with the same permissions, I think this needs to be improved both for phones and for regular Linux systems which will probably benefit more than phones do. I ll write another blog post about this.

15 March 2022

Russell Coker: Librem 5 First Impression

I just received the Purism Librem 5 that I paid for years ago (I think it was 2018). The process of getting the basic setup done was typical (choosing keyboard language, connecting to wifi, etc). Then I tried doing things. One thing I did was update to the latest PureOS release which gave me a list of the latest Debian packages installed which is nice. The first problem I found was the lack of notification when the phone is trying to do something. I d select to launch an app, nothing would happen, then a few seconds later it would appear. When I go to the PureOS app store and get a list of apps in a category nothing happens for ages (shows a blank list) then it might show actual apps, or it might not. I don t know what it s doing, maybe downloading a list of apps, if so it should display how many apps have had their summary data downloaded or how many KB of data have been downloaded so I know if it s doing something and how long it might take. Running any of the productivity applications requires a GNOME keyring, I selected a keyring password of a few characters and it gave a warning about having no password (does this mean it took 3 characters to be the same as 0 characters?). Then I couldn t unlock it later. I tried deleting the key file and creating a new one with a single character password and got the same result. I think that such keyring apps have little benefit, all processes in the session have the same UID and presumable can use ptrace to get data from each other s memory space. If the keyring program was SETGID and the directory used to store the keyring files was a system directory with execute access only for that group then it might provide some benefit (SETGID means that ptrace is denied). Ptrace is denied for the keyring but relying on a user space prompt for the passphrase to a file that the user can read seems of minimal benefit as a hostile process could read the file and prompt for the passphrase. This is probably more of a Debian issue, and I reproduced the keyring issue with my Debian workstation. The Librem 5 is a large phone (unusually thick by modern phone standards) and is rumoured to be energy hungry. When I tried charging it from the USB port on my PC (HP ML110 Gen9) the charge level went down. I used the same USB port and USB cable that I use to charge my Huawei Mate 10 Pro every day, so other phones can draw more power from that USB port and cable faster than they use it. The on-sceen keyboard for the Librem 5 is annoying, it doesn t have a TAB key and the cursor control keys are unreasonably small. The keyboard used by ConnectBot (the most popular SSH client for Android) is much better, it has it s own keys for CTRL, ESC, TAB, arrows, HOME, and END in addition to the regular on-screen keyboard. The Librem 5 comes with a terminal app by default which is much more difficult to use than it should be due to the lack of TAB filename completion etc. The phone has a specified temperature range of 0C to 35C, that s not great for Australia where even the cooler cities have summer temperatures higher than that. When charging on a fast charger (one that can provide energy faster than the phone uses it) the phone gets quite warm. It feels like more than 10C hotter than the ambient temperature, so I guess I can t charge it on Monday afternoon when the forecast is 31C! Maybe I should put a USB charger by my fridge with a long enough cable that I can charge a phone that s inside the fridge, seriously. Having switches to disable networking is a good security feature and designing the phone with separate components that can t interfere with each other is good too. There are reports that software fixes will reduce the electricity use which will alleviate the problems with charging and temperature. Most of my problems are clearly software related and therefore things that I can fix (in theory at least I don t have unlimited coding time). Overall this wasn t the experience I had hoped for after spending something like $700 and waiting about 4 years (so long that I can t easily find the records of how long and how much money). Getting It Working It seems that the PureOS app store app doesn t work properly. I can visit the app site and then select an app to install which then launches the app store app to do the install, which failed for every app I tried. Then I tried going to the terminal and running the following:
sudo bash
apt update
apt install openssh-server netcat
So I should be able to use APT to install everything I want and use the PureOS web site as a guide to what is expected to work on the phone. As an aside the PureOS apt repository appears to be a mirror or rebuild of the Debian/Bullseye arm64 archive without non-free components that they call Byzanteum. Then I could ssh to my phone via ssh purism@purism (after adding an entry to /etc/hosts with the name purism and a static entry in my DHCP configuration to match) and run sudo bash to get root. To be able to login to root directly I had to install a ssh key (root is setup to login without password) and run usermod --expiredate= root (empty string for expire date) to have direct root logins. I put the following in /etc/ssh/sshd_config.d/local.conf to restrict who can login (I added the users I want to the sshusers group). It also uses the ClientAlive checks because having sessions break due to IP address changes is really common with mobile devices and we don t want disconnected sessions taking up memory forever.
AllowGroups sshusers
PasswordAuthentication no
UseDNS no
ClientAliveInterval 60
ClientAliveCountMax 6
Notifications The GNOME notification system is used for notifications in the phone UI. So if you install the package libnotify-bin you get a utility notify-send that allows sending notifications from shell scripts. Final Result Now it basically works as a Debian workstation with a single-button mouse. So I just need to configure it as I would a Debian system and fix bugs along the way. Presumably any bug fixes I get into Debian will appear in PureOS shortly after the next Debian release.

1 March 2022

Russell Coker: SAGE (ITPA) Spam

In 2008 I joined SAGE (the System Administrators Guild of Australia). It was a professional society for people doing sysadmin work (running computer servers). I quit when I found that the level of clue was lower than hoped and that members used the code of ethics as nothing but a way to score points in online debates. After quitting SAGE kept emailing me and wouldn t respect my request to be removed from all lists so I had to block their mail server. SAGE has in recent times changed it s name to ITPA (Information Technology Professionals Association) and is still sending me email. I ve just sent yet another unsubscribe request. How many years of sending unwanted email can be caused by incompetence and when should we assume it s malice? They have been doing this for over a decade now. Even if it s incompetence, that s still damning given that it s incompetence in the main topic of the organisation. Here is the ITPA Code of Ethics [1], as you can see there is no reference to spam. The nearest seems to be I will continue to enlarge my understanding of the social and legal issues that arise in computing environments, and I will communicate that understanding to others when appropriate . So it s great that they aren t breaking their own code of ethics :-# but I d still like them to stop emailing me.

10 February 2022

Russell Coker: Mouse and Teflon

I had a problem with my mouse. The slippery plastic bits on the bottom weren t glued on well and came off, which then gave more friction when moving on the desk. After asking advice on a mailing list the best suggestion was Teflon sticky tape. I bought a few meters of such tape (a lifetime supply for mouse repair) and used an 8cm strip on each side of the bottom of my mouse which made it slippery enough. Ebay seems like a good place to buy that, most of the offers are well below $20 for a reel of tape including postage. One thing to note is that they also sell non-adhesive teflon tape. I made the mistake of investigating the capabilities of teflon tape then buying the cheapest one on offer which turned out to be plumber s tape which doesn t have adhesive, fortunately it was well below $10. I now have a lifetime supply of plumber s tape if I can ever find a use for it.

1 February 2022

Russell Coker: First Flounder Meeting

Based on a comment from my previous post [1] I have named the new FOSS group for Australia and NZ Flounder. Here is the link to the agenda for the first meeting [2]. I am currently using a DNS name in my own domain for the group, but in the near future I ll move it to somewhere else under a zone I don t control. My aim is not to have personal control but to create an organisation for the community. But at the moment I m just doing things in the fastest way possible, I will setup HTTP redirects when I get a better DNS name.

30 January 2022

Russell Coker: Links Jan 2022

Washington Post has an interesting article on how gender neutral language is developing in different countries [1]. pimaker has an interesting blog post about how they wrote a RISCV CPU emulator to boot a Linux kernel in a pixel shader in the VR Chat platform [2]. ZD has an interesting article about the new Solo Bumblebee platform for writing EBPF programs to run inside the Linux kernel [3]. EBPF is an interesting platform and it s good to have new tools to help people develop for it. Big Think has an interesting article about augmented reality suggesting that it could be worse than social media for driving disputes [4]. Some people would want tags of racial status on all people they see. Vice has an insightful article making the case for 8 hours of work per week [5]. The Guardian has an insightful article about how our attention is being stolen by modern technology [6]. Interesting article about the Ilobleed rootkit that targets the HP ILO server management system [7], it s apparently designed for persistent attacks as it bypasses the firmware upgrade process and updates only the version number so anyone who thinks that a firmware update will fix it is horribly mislead. Nick Bostrom wrote an insightful and disturbing article for Aeon titles None of Our Technologies has Managed to Destroy Humanity Yet [8] about the existential risk of new technologies and how they might be mitigated, much of which involves authoritarian governments unlike any we have seen before. As a counterpoint the novel A Deepness in the Sky claims that universal surveillance would be as damaging to the future of a society as planet-buster bombs. Euronews has an informative article about eco-fascism [9]. The idea that the solution to ecological problems is to have less people in the world and particularly less non-white people is a gateway from green politics to fascism. The developer of the colors and faker npm libraries (for NodeJS) recently uploaded corrupted versions of those libraries as a protest against companies that use them without paying him [10]. This is the wrong way to approach the issue, but it does demonstrate a serious problem with systems like NPM that allow automatic updates. It gives a better result to just use software packaged by a distribution which has QA checks applied including on security updates. VentureBeat has an interesting article on the way that AI is taking over jobs [11]. Lots of white collar jobs can be replaced by machine learning systems, we need to plan for the ways this will change the economy. The Atlantic has an interesting article about tapeworms that infect some ants [12]. The tapeworms make the ants live longer and produce pheromones to make the other ants serve them. This increases the chance that the ants will be eaten by birds which is the next stage in the tapeworm lifecycle.

26 January 2022

Russell Coker: Australia/NZ Linux Meetings

I am going to start a new Linux focused FOSS online meeting for people in Australia and nearby areas. People can join from anywhere but the aim will be to support people in nearby areas. To cover the time zone range for Australia this requires a meeting on a weekend, I m thinking of the first Saturday of the month at 1PM Melbourne/Sydney time, that would be 10AM in WA and 3PM in NZ. We may have corner cases of daylight savings starting and ending on different days, but that shouldn t be a big deal as I think those times can vary by an hour either way without being too inconvenient for anyone. Note that I describe the meeting as Linux focused because my plans include having a meeting dedicated to different versions of BSD Unix and a meeting dedicated to the HURD. But those meetings will be mainly for Linux people to learn about other Unix-like OSs. One focus I want to have for the meetings is hands-on work, live demonstrations, and short highly time relevant talks. There are more lectures on YouTube than anyone could watch in a lifetime (see the Linux.conf.au channel for some good ones [1]). So I want to run events that give benefits that people can t gain from watching YouTube on their own. Russell Stuart and I have been kicking around ideas for this for a while. I think that the solution is to just do it. I know that Saturday won t work for everyone (no day will) but it will work for many people. I am happy to discuss changing the start time by an hour or two if that seems likely to get more people. But I m not particularly interested in trying to make it convenient for people in Hawaii or India, my idea is for an Australia/NZ focused event. I would be more than happy to share lecture notes etc with people in other countries who run similar events. As an aside I d be happy to give a talk for an online meeting at a Hawaiian LUG as the timezone is good for me. Please pencil in 1PM Melbourne time on the 5th of Feb for the first meeting. The meeting requirements will be a PC with good Internet access running a recent web browser and a ssh client for the hands-on stuff. A microphone or webcam is NOT required, any questions you wish to ask can be done with text if that s what you prefer. Suggestions for the name of the group are welcome.

16 January 2022

Russell Coker: SSD Endurance

I previously wrote about the issue of swap potentially breaking SSD [1]. My conclusion was that swap wouldn t be a problem as no normally operating systems that I run had swap using any significant fraction of total disk writes. In that post the most writes I could see was 128GB written per day on a 120G Intel SSD (writing the entire device once a day). My post about swap and SSD was based on the assumption that you could get many thousands of writes to the entire device which was incorrect. Here s a background on the terminology from WD [2]. So in the case of the 120G Intel SSD I was doing over 1 DWPD (Drive Writes Per Day) which is in the middle of the range of SSD capability, Intel doesn t specify the DWPD or TBW (Tera Bytes Written) for that device. The most expensive and high end NVMe device sold by my local computer store is the Samsung 980 Pro which has a warranty of 150TBW for the 250G device and 600TBW for the 1TB device [3]. That means that the system which used to have an Intel SSD would have exceeded the warranty in 3 years if it had a 250G device. My current workstation has been up for just over 7 days and has averaged 110GB written per day. It has some light VM use and the occasional kernel compile, a fairly typical developer workstation. It s storage is 2*Crucial 1TB NVMe devices in a BTRFS RAID-1, the NVMe devices are the old series of Crucial ones and are rated for 200TBW which means that they can be expected to last for 5 years under the current load. This isn t a real problem for me as the performance of those devices is lower than I hoped for so I will buy faster ones before they are 5yo anyway. My home server (and my wife s workstation) is averaging 325GB per day on the SSDs used for the RAID-1 BTRFS filesystem for root and for most data that is written much (including VMs). The SSDs are 500G Samsung 850 EVOs [4] which are rated at 150TBW which means just over a year of expected lifetime. The SSDs are much more than a year old, I think Samsung stopped selling them more than a year ago. Between the 2 SSDs SMART reports 18 uncorrectable errors and btrfs device stats reports 55 errors on one of them. I m not about to immediately replace them, but it appears that they are well past their prime. The server which runs my blog (among many other things) is averaging over 1TB written per day. It currently has a RAID-1 of hard drives for all storage but it s previous incarnation (which probably had about the same amount of writes) had a RAID-1 of enterprise SSDs for the most written data. After a few years of running like that (and some time running with someone else s load before it) the SSDs became extremely slow (sustained writes of 15MB/s) and started getting errors. So that s a pair of SSDs that were burned out. Conclusion The amounts of data being written are steadily increasing. Recent machines with more RAM can decrease storage usage in some situations but that doesn t compare to the increased use of checksummed and logged filesystems, VMs, databases for local storage, and other things that multiply writes. The amount of writes allowed under warranty isn t increasing much and there are new technologies for larger SSD storage that decrease the DWPD rating of the underlying hardware. For the systems I own it seems that they are all going to exceed the rated TBW for the SSDs before I have other reasons to replace them, and they aren t particularly high usage systems. A mail server for a large number of users would hit it much earlier. RAID of SSDs is a really good thing. Replacement of SSDs is something that should be planned for and a way of swapping SSDs to less important uses is also good (my parents have some SSDs that are too small for my current use but which work well for them). Another thing to consider is that if you have a server with spare drive bays you could put some extra SSDs in to spread the wear among a larger RAID-10 array. Instead of having a 2*SSD BTRFS RAID-1 for a server you could have 6*SSD to get a 3* longer lifetime than a regular RAID-1 before the SSDs wear out (BTRFS supports this sort of thing). Based on these calculations and the small number of errors I ve seen on my home server I ll add a 480G SSD I have lying around to the array to spread the load and keep it running for a while longer.

9 January 2022

Russell Coker: Video Conferencing (LCA)

I ve just done a tech check for my LCA lecture. I had initially planned to do what I had done before and use my phone for recording audio and video and my PC for other stuff. The problem is that I wanted to get an external microphone going and plugging in a USB microphone turned off the speaker in the phone (it seemed to direct audio to a non-existent USB audio output). I tried using bluetooth headphones with the USB microphone and that didn t work. Eventually a viable option seemed to be using USB headphones on my PC with the phone for camera and microphone. Then it turned out that my phone (Huawei Mate 10 Pro) didn t support resolutions higher than VGA with Chrome (it didn t have the advanced settings menu to select resolution), this is probably an issue of Android build features. So the best option is to use a webcam on the PC, I was recommended a Logitech C922 but OfficeWorks only has a Logitech C920 which is apparently OK. The free connection test from freeconference.com [1] is good for testing out how your browser works for videoconferencing. It tests each feature separately and is easy to run. After buying the C920 webcam I found that it sometimes worked and sometimes caused a kernel panic like the following (partial panic log included for the benefit of people Googling this Logitech C920 problem):
[95457.805417] BUG: kernel NULL pointer dereference, address: 0000000000000000
[95457.805424] #PF: supervisor read access in kernel mode
[95457.805426] #PF: error_code(0x0000) - not-present page
[95457.805429] PGD 0 P4D 0 
[95457.805431] Oops: 0000 [#1] SMP PTI
[95457.805435] CPU: 2 PID: 75486 Comm: v4l2src0:src Not tainted 5.15.0-2-amd64 #1  Debian 5.15.5-2
[95457.805438] Hardware name: HP ProLiant ML110 Gen9/ProLiant ML110 Gen9, BIOS P99 02/17/2017
[95457.805440] RIP: 0010:usb_ifnum_to_if+0x3a/0x50 [usbcore]
...
[95457.805481] Call Trace:
[95457.805484]  
[95457.805485]  usb_hcd_alloc_bandwidth+0x23d/0x360 [usbcore]
[95457.805507]  usb_set_interface+0x127/0x350 [usbcore]
[95457.805525]  uvc_video_start_transfer+0x19c/0x4f0 [uvcvideo]
[95457.805532]  uvc_video_start_streaming+0x7b/0xd0 [uvcvideo]
[95457.805538]  uvc_start_streaming+0x2d/0xf0 [uvcvideo]
[95457.805543]  vb2_start_streaming+0x63/0x100 [videobuf2_common]
[95457.805550]  vb2_core_streamon+0x54/0xb0 [videobuf2_common]
[95457.805555]  uvc_queue_streamon+0x2a/0x40 [uvcvideo]
[95457.805560]  uvc_ioctl_streamon+0x3a/0x60 [uvcvideo]
[95457.805566]  __video_do_ioctl+0x39b/0x3d0 [videodev]
It turns out that Ubuntu Launchpad bug #1827452 has great information on this problem [2]. Apparently if the device decides it doesn t have enough power then it will reconnect and get a different USB bus device number and this often happens when the kernel is initialising it. There s a race condition in the kernel code in which the code to initialise the device won t realise that the device has been detached and will dereference a NULL pointer and then mess up other things in USB device management. The end result for me is that all USB devices become unusable in this situation, commands like lsusb hang, and a regular shutdown/reboot hangs because it can t kill the user session because something is blocked on USB. One of the comments on the Launchpad bug is that a powered USB hub can alleviate the problem while a USB extension cable (which I had been using) can exacerbate it. Officeworks currently advertises only one powered USB hub, it s described as USB 3 but also maximum speed 480 Mbps (USB 2 speed). So basically they are selling a USB 2 hub for 4* the price that USB 2 hubs used to sell for. When debugging this I used the cheese webcam utility program and ran it in a KVM virtual machine. The KVM parameters -device qemu-xhci -usb -device usb-host,hostbus=1,hostaddr=2 (where 1 and 2 are replaced by the Bus and Device numbers from lsusb ) allow the USB device to be passed through to the VM. Doing this meant that I didn t have to reboot my PC every time a webcam test failed. For audio I m using the Sades Wand gaming headset I wrote about previously [3].

4 January 2022

Russell Coker: Terrorists Inspired by Fiction

The Tom Clancy book Debt of Honor published in August 1994 first introduced the concept of a heavy passenger aircraft being used as a weapon by terrorists against a well defended building. In April 1994 there was an attempt to hijack and deliberately crash FedEx flight 705. It s possible for a book to be changed 4 months before publication, but it seems unlikely that a significant plot point in a series of books was changed in such a small amount of time so it s likely that Tom Clancy got the idea first. There have been other variations on that theme, such as the Yokosuka_MXY-7 Kamakazi flying bomb (known by the Allies as Baka which is Japanese for idiot). But Tom Clancy seemed to pioneer the idea of a commercial passenger jet being subverted for the purpose of ground attack. 7 years after Tom Clancy s book was published the 911 hijackings happened. The TV series Black Mirror first aired in 2011, and the first episode was about terrorists kidnapping a princess and demanding that the UK PM perform an indecent act with a pig for her release. While the plot was a little extreme (the entire series is extreme) the basic concept of sexual extortion based on terrorist acts is something that could be done in real life, and if terrorists were inspired by this they are taking longer than expected to do it. Most democracies seem to end up with two major parties that are closely matched. Even if a government was strict about not negotiating with terrorists it seems likely that terrorists demanding that a politician perform an unusual sex act on TV would change things, supporters would be divided into groups that support and oppose negotiating. Discussions wouldn t be as civil as when the negotiation involves money or freeing prisoners. If an election result was perceived to have been influenced by such terrorism then supporters of the side that lost would claim it to be unfair and reject the result. If the goal of terrorists was to cause chaos then that would be one way of achieving it, and they have had over 10 years to consider this possibility. Are we overdue for a terror attack inspired by Black Mirror?

Russell Coker: Big Smart TVs

Recently a relative who owned a 50 Plasma TV asked me for advice on getting a new TV. Looking at the options all the TVs seem to be smart TVs (running Android with built in support for YouTube and Netflix) and most of them seem to be 4K resolution. 4K doesn t provide much benefit now as most people don t have BlueRay DVD players and discs, there aren t a lot of 4K YouTube videos, and most streaming services don t offer 4K resolution. But as 4K doesn t cost much more it doesn t make sense not to get it. I gave my relative a list of good options from Kogan (the Australian company that has the cheapest consumer electronics) and they chose a 65 4K Smart TV from Kogan. That only cost $709 plus delivery which is reasonably affordable for something that will presumably last for a long time and be used by many people. Netflix on a web browser won t do more than FullHD resolution unless you use Edge on Windows 10. But Netflix on the smart tv has a row advertising 4K shows which indicates that 4K is supported. There are some 4K videos on YouTube but not a lot at this time. Size It turns out that 65 is very big. It didn t fit on the table that had been used for the 50 Plasma TV. Rtings.com has a good article about TV size vs distance [1]. According to their calculations if you want to sit 2 meters away from a TV and have a 30 degree field of view (recommended for mixed use) then a 45 TV is ideal. According to their calculations on pixel sizes, if you have a FullHD display (or the common modern case a FullHD signal displayed on a 4K monitor) that is between 1.8 and 2.5 meters away from you then a 45 TV is the largest that will be useful. To take proper advantage of a monitor larger than 45 at a distance of 2 meters you need a 4K signal. If you have a 4K signal then you can get best results by having a 45 monitor less than 1.8 meters away from you. As most TV watching involves less than 3 people it shouldn t be inconvenient to be less than 1.8 meters away from the TV. The 65 TV weighs 21Kg according to the specs, that isn t a huge amount for something small, but for something a large and inconvenient as a 65 TV it s impossible for one person to safely move. Kogan sells 43 TVs that weigh 6KG, that s something that most adults could move with one hand. I think that a medium size TV that can be easily moved to a convenient location would probably give an equivalent viewing result to an extremely large TV that can t be moved at all. I currently have a 40 LCD TV, the only reason I have that is because a friend didn t need it, the previous 32 TV that I used was adequate for my needs. Most of my TV viewing is on a 28 monitor, which I find adequate for 2 or 3 people. So I generally wouldn t recommend a 65 TV for anyone. Android for TVs Android wasn t designed for TVs and doesn t work that well on them. Having buttons on the remote for Netflix and YouTube is handy, but it would be nice if there were programmable buttons for other commonly used apps or a way to switch between the last few apps (like ALT-TAB on a PC). One good feature of Android for TV is that it can display a set of rows of shows (similar to the Netflix method of displaying) where each row is from a different app. The apps I ve installed on that TV which support the row view are Netflix, YouTube, YouTube Music, ABC iView (that s Australian ABC), 7plus, 9now, and SBS on Demand. That s nice, now we just need channel 10 s app to support that to have coverage for all Australian free TV stations in the Android TV interface. Conclusion It s a nice TV and it generally works well. Android is OK for TV use but far from great. It is running Android version 9, maybe a newer version of Android works better on TVs. It s too large for reasonable people to use in a home. I ve seen smaller TVs used for 20 people in an office in a video conference. It s cheap enough that most people can afford it, but it s easier and more convenient to have something smaller and lighter.

Russell Coker: Curiosity Stream

I have recently signed up for the Curiosity Stream [1] documentary site, this is designed to be like Netflix but for non-fiction content only. The service costs $US15 per annum or $52US per annum for 4K (I think the 4K service was about $US120 per annum when I signed up). The extra price for 4K seems excessive, while it is in line with the bandwidth requirements a large portion of the costs of the service would be about user support and running the service reliably for which 4K makes little difference. My aim in subscribing was to just get a service like Netflix with new documentary content as I have watched every documentary I want to watch on Netflix (I think I ve watched over 1000 hours of Netflix documentaries). So naturally I compare the service to Netflix and I found that it doesn t compare well. Curiosity Stream (CS) has no button to skip the intro and has a problem with using the right arrow to skip forward (seems to only work once and then I have to use the mouse), this costs me about 30 seconds for each episode which adds up when watching documentaries at 1.5* speed. The method of controlling the viewing is a little clunky, sometimes the popup menu at the bottom of the screen to control playback doesn t disappear by itself until you mouse over it and space bar doesn t select pause instead it selects the last action. CS allows selecting individual episodes for your watch list instead of entire series, this could be useful for some people but I just find it annoying, it might be good for classroom use. The method of searching for new shows to watch isn t as good as the Netflix method or the way things are displayed on Android TV (which seems to have an API for multiple video providers to show a list of shows with one row per provider). Some of these things might seem OK if you haven t used other services, but if you are used to Netflix and Amazon Prime then it will seem clunky. The amount of content on Curiosity Stream doesn t seem that large, I don t know how to get a full measure of it, but when I search for things I seem to get less results than on Netflix. That could be something to do with what I m searching for. In terms of value for money $US15 per annum for the content that CS provides is a good deal. Netflix overall offers better value for home users having fiction as well as non-fiction in large quantities. But for documentary content $US15 per annum is pretty cheap. I recommend signing up for CS, but for most people signing up for Netflix first will be a good option.
  1. [1] https://curiositystream.com/

31 December 2021

Russell Coker: Links December 2021

Wired magazine has many short documentary films on YouTube, this one about How Photography is Affecting Our Brains is particularly good [1]. Matt Blaze wrote an informative blog post about Faraday cages for phones [2]. It seems that the commercial shielded bags are all pretty good while doing it yourself with aluminium foil may get similar results or may get much worse results with no obvious difference in the quality of the wrapping. Aluminium foil doesn t protect that well and doesn t protect consistently. A metal biscuit tin performed quite well and consistently, so that s a cheap option for reducing signals. Umair Haque wrote an insightful article about the single word that describes most of the problems the world faces right now [3]. Forbes has an informative article about the early days of the Ford company when they doubled wages, it proves that they didn t do so to enable workders to afford cars but to avoid staff turnover (which is expensive) [4]. Also the Ford company had a fascistic approach to employees, controlling what they were allowed to do in their spare time if they wanted the bonus payment. The wages weren t doubled, there was a bonus payment that would double the salary if the employee was eligible for the bonus. One thing that Forbes gets wrong is that they claim that it was only having higher pay than other companies that provided a benefit and that a higher minimum wage wouldn t, the problem with that idea is that a higher minimum wage would discourage people from having multiple jobs and allow more families to not have the mother working (a condition for a man to get the Ford bonus was for his wife to not work). The WSJ has an interesting article about Intel s datacenter for running all the different configurations of CPUs that they have supported over the last 10 years for security tests [5]. My Thinkpad (which is less than 10yo) is vulnerable to one of the SPECTRE family of exploits as Intel hasn t released microcode to fix it, getting fixed microcode out for all the systems from major vendors like Lenovo would be a good idea if they want to improve their security. NPR has an interesting article about the correlation between support for Trump in counties of the US with lack of vaccination and Covid19 deaths [6]. No surprises, but it s good to see the graphs. Cory Doctorow wrote an interesting article on the lack of slack in the current American education system [7]. It s not that bad in Australia but we are unfortunately moving in the American direction. Teen Vogue has an insightful article about the problems with the focus on resilience [8], while resilience is good we should make it a higher priority to avoid putting people in situations where they need to be resiliant than on encouraging resilience.

12 December 2021

Russell Coker: Some Ideas for Debian Security Improvements

Debian security is pretty good, but there s always scope for improvement. Here are some ideas that I think could be used to improve things.
  1. A security wizard , basically a set of scripts with support for plugins that will investigate your system and look for things that can be improved. It could give suggestions on LSMs that could be used, sysctl settings, lists of daemons running as root that possibly don t need root privs, etc. Plugins could be for different daemons, so there could be a plugin for Apache that looks for potential issues with Apache configuration. It wouldn t be possible to cover everything, but it would be possible to cover many common cases.
    It appears that we used to have a harden package to do some of these things which disappeared. It appears that the only remnant of that is the hardening-runtime package.
  2. Kali Linux [1] is a distribution designed for penetration testing, I recently tried out many of it s features and I was very impressed. While I don t think that the aim should be to copy all Kali features into Debian there are probably some that are worthy of inclusion. Most Kali features run well in a VM, but the Wifi penetration testing tools need access to the hardware, so they could be a good candidate for inclusion in Debian (license permitting).
  3. We have a Securing Debian Manual [2] that is really good. It s a little out of date and needs some contributions, it also needs to be better known.
  4. The Security Management page of the Debian wiki [3] has links to a number of pages about improving system security. It needs some updates, it doesn t have a link to a page about SE Linux so there s some work for me to do there.
  5. Can training help people? I would be happy to run some Debian SE Linux training sessions over Matrix or Jitsi. We can probably find people to offer training on other aspects of Linux security that are implemented in Debian if there is an audience. I don t think that I and other DDs (Debian Developers) can train everyone, but we could train people who then go on to run other training sessions and make the session notes etc available under the GPL.
    There would also be some benefits to training other DDs as probably no-one has a good overview of all the security features that are supported.
Any other ideas? Feel free to comment here or start a thread on a public mailing list. If you start a mailing list discussion please email me or comment here with the URL if it s a list that I m not on so I can track it via the archives. This post was inspired by a discussion on a private list of a related topic. I think it s better to have a public discussion instead.

9 December 2021

David Kalnischkies: APT for Advent of Code

Screenshot of my Advent of Code 2021 status page as of today Advent of Code 2021
Advent of Code, for those not in the know, is a yearly Advent calendar (since 2015) of coding puzzles many people participate in for a plenary of reasons ranging from speed coding to code golf with stops at learning a new language or practicing already known ones. I usually write boring C++, but any language and then some can be used. There are reports of people implementing it in hardware, solving them by hand on paper or using Microsoft Excel so, after solving a puzzle the easy way yesterday, this time I thought: CHALLENGE ACCEPTED! as I somehow remembered an old 2008 article about solving Sudoku with aptitude (Daniel Burrows via archive.org as the blog is long gone) and the good same old a package management system that can solve [puzzles] based on package dependency rules is not something that I think would be useful or worth having (Russell Coker). Day 8 has a rather lengthy problem description and can reasonably be approached in a bunch of different way. One unreasonable approach might be to massage the problem description into Debian packages and let apt help me solve the problem (specifically Part 2, which you unlock by solving Part 1. You can do that now, I will wait here.) Be warned: I am spoiling Part 2 in the following, so solve it yourself first if you are interested. I will try to be reasonable consistent in naming things in the following and so have chosen: The input we get are lines like acedgfb cdfbe gcdfa fbcad dab cefabd cdfgeb eafb cagedb ab cdfeb fcadb cdfeb cdbaf. The letters are wires mixed up and connected to the segments of the displays: A group of these letters is hence a digit (the first 10) which represent one of the digits 0 to 9 and (after the pipe) the four displays which match (after sorting) one of the digits which means this display shows this digit. We are interested in which digits are displayed to solve the puzzle. To help us we also know which segments form which digit, we just don't know the wiring in the back. So we should identify which wire maps to which segment! We are introducing the packages wire-X-connects-to-Y for this which each provide & conflict1 with the virtual packages segment-Y and wire-X-connects. The later ensures that for a given wire we can only pick one segment and the former ensures that not multiple wires map onto the same segment. As an example: wire a's possible association with segment b is described as:
Package: wire-a-connects-to-b
Provides: segment-b, wire-a-connects
Conflicts: segment-b, wire-a-connects
Note that we do not know if this is true! We generate packages for all possible (and then some) combinations and hope dependency resolution will solve the problem for us. So don't worry, the hard part will be done by apt, we just have to provide all (im)possibilities! What we need now is to translate the 10 digits (and 4 outputs) from something like acedgfb into digit-0-is-eight and not, say digit-0-is-one. A clever solution might realize that a one consists only of two segments so a digit wiring up seven segments can not be a 1 (and must be 8 instead), but again we aren't here to be clever: We want apt to figure that out for us! So what we do is simply making every digit-0-is-N (im)possible choice available as a package and apply constraints: A given digit-N can only display one number and each N is unique as digit so for both we deploy Provides & Conflicts again. We also need to reason about the segments in the digits: Each of the digit packages gets Depends on wire-X-connects-to-Y where X is each possible wire (e.g. acedgfb) and Y each segment forming the digit (e.g. cf for one). The different choices for X are or'ed together, so that either of them satisfies the Y. We know something else too through: The segments which are not used by the digit can not be wired to any of the Xs. We model this with Conflicts on wire-X-connects-to-Y. As an example: If digit-0s acedgfb would be displaying a one (remember, it can't) the following package would be installable:
Package: digit-0-is-one
Version: 1
Depends: wire-a-connects-to-c   wire-c-connects-to-c   wire-e-connects-to-c   wire-d-connects-to-c   wire-g-connects-to-c   wire-f-connects-to-c   wire-b-connects-to-c,
         wire-a-connects-to-f   wire-c-connects-to-f   wire-e-connects-to-f   wire-d-connects-to-f   wire-g-connects-to-f   wire-f-connects-to-f   wire-b-connects-to-f
Provides: digit-0, digit-is-one
Conflicts: digit-0, digit-is-one,
  wire-a-connects-to-a, wire-c-connects-to-a, wire-e-connects-to-a, wire-d-connects-to-a, wire-g-connects-to-a, wire-f-connects-to-a, wire-b-connects-to-a,
  wire-a-connects-to-b, wire-c-connects-to-b, wire-e-connects-to-b, wire-d-connects-to-b, wire-g-connects-to-b, wire-f-connects-to-b, wire-b-connects-to-b,
  wire-a-connects-to-d, wire-c-connects-to-d, wire-e-connects-to-d, wire-d-connects-to-d, wire-g-connects-to-d, wire-f-connects-to-d, wire-b-connects-to-d,
  wire-a-connects-to-e, wire-c-connects-to-e, wire-e-connects-to-e, wire-d-connects-to-e, wire-g-connects-to-e, wire-f-connects-to-e, wire-b-connects-to-e,
  wire-a-connects-to-g, wire-c-connects-to-g, wire-e-connects-to-g, wire-d-connects-to-g, wire-g-connects-to-g, wire-f-connects-to-g, wire-b-connects-to-g
Repeat such stanzas for all 10 possible digits for digit-0 and then repeat this for all the other nine digit-N. We produce pretty much the same stanzas for display-0(-is-one), just that we omit the second Provides & Conflicts from above (digit-is-one) as in the display digits can be repeated. The rest is the same (modulo using display instead of digit as name of course). Lastly we create a package dubbed solution which depends on all 10 digit-N and 4 display-N all of them virtual packages apt will have to choose an installable provider from and we are nearly done! The resulting Packages file2 we can give to apt while requesting to install the package solution and it will spit out not only the display values we are interested in but also which number each digit represents and which wire is connected to which segment. Nifty!
$ ./skip-aoc 'acedgfb cdfbe gcdfa fbcad dab cefabd cdfgeb eafb cagedb ab   cdfeb fcadb cdfeb cdbaf'
[ ]
The following additional packages will be installed:
  digit-0-is-eight digit-1-is-five digit-2-is-two digit-3-is-three
  digit-4-is-seven digit-5-is-nine digit-6-is-six digit-7-is-four
  digit-8-is-zero digit-9-is-one display-1-is-five display-2-is-three
  display-3-is-five display-4-is-three wire-a-connects-to-c
  wire-b-connects-to-f wire-c-connects-to-g wire-d-connects-to-a
  wire-e-connects-to-b wire-f-connects-to-d wire-g-connects-to-e
[ ]
0 upgraded, 22 newly installed, 0 to remove and 0 not upgraded.
We are only interested in the numbers on the display through, so grepping the apt output (-V is our friend here) a bit should let us end up with what we need as calculating3 is (unsurprisingly) not a strong suit of our package relationship language so we need a few shell commands to help us with the rest.
$ ./skip-aoc 'acedgfb cdfbe gcdfa fbcad dab cefabd cdfgeb eafb cagedb ab   cdfeb fcadb cdfeb cdbaf' -qq
5353
I have written the skip-aoc script as a testcase for apt, so to run it you need to place it in /path/to/source/of/apt/test/integration and built apt first, but that is only due to my laziness. We could write a standalone script interfacing with the system installed apt directly and in any apt version since ~2011. To hand in the solution for the puzzle we just need to run this on each line of the input (~200 lines) and add all numbers together. In other words: Behold this beautiful shell one-liner: parallel -I ' ' ./skip-aoc ' ' -qq < input.txt paste -s -d'+' - bc (You may want to run parallel with -P to properly grill your CPU as that process can take a while otherwise and it still does anyhow as I haven't optimized it at all the testing framework does a lot of pointless things wasting time here, but we aren't aiming for the leaderboard so ) That might or even likely will fail through as I have so far omitted a not unimportant detail: The default APT resolver is not able to solve this puzzle with the given problem description we need another solver! Thankfully that is as easy as installing apt-cudf (and with it aspcud) which the script is using via --solver aspcud to make apt hand over the puzzle to a "proper" solver (or better: A solver who is supposed to be good at "answering set" questions). The buildds are using this for experimental and/or backports builds and also for installability checks via dose3 btw, so you might have encountered it before. Be careful however: Just because aspcud can solve this puzzle doesn't mean it is a good default resolver for your day to day apt. One of the reasons the default resolver has such a hard time solving this here is that or-groups have usually an order in which the first is preferred over every later option and so fort. This is of no concern here as all these alternatives will collapse to a single solution anyhow, but if there are multiple viable solutions (which is often the case) picking the "wrong" alternative can have bad consequences. A classic example would be exim4 postfix nullmailer. They are all MTAs but behave very different. The non-default solvers also tend to lack certain features like keeping track of auto-installed packages or installing Recommends/Suggests. That said, Julian is working on another solver as I write this which might deal with more of these issues. And lastly: I am also relatively sure that with a bit of massaging the default resolver could be made to understand the problem, but I can't play all day with this maybe some other day. Disclaimer: Originally posted in the daily megathread on reddit, the version here is just slightly better understandable as I have hopefully renamed all the packages to have more conventional names and tried to explain what I am actually doing. No cows were harmed in this improved version, either.

  1. If you would upload those packages somewhere, it would be good style to add Replaces as well, but it is of minor concern for apt so I am leaving them out here for readability.
  2. We have generated 49 wires, 100 digits, 40 display and 1 solution package for a grant total of 190 packages. We are also making use of a few purely virtual ones, but that doesn't add up to many packages in total. So few packages are practically childs play for apt given it usually deals with thousand times more. The instability for those packages tends to be a lot better through as only 22 of 190 packages we generated can (and will) be installed. Britney will hate you if your uploads to Debian unstable are even remotely as bad as this.
  3. What we could do is introduce 10.000 packages which denote every possible display value from 0000 to 9999. We would then need to duplicate our 10.190 packages for each line (namespace them) and then add a bit more than a million packages with the correct dependencies for summing up the individual packages for apt to be able to display the final result all by itself. That would take a while through as at that point we are looking at working with ~22 million packages with a gazillion amount of dependencies probably overworking every solver we would throw at it a bit of shell glue seems the better option for now.
This article was written by David Kalnischkies on apt-get a life and republished here by pulling it from a syndication feed. You should check there for updates and more articles about apt and EDSP.

7 December 2021

Russell Coker: AS400

The IBM i operating system on the AS/400 is a system that runs on PPC for midrange systems. I did a bit of reading about it after seeing an AS/400 on ebay for $300, if I had a lot more spare time and energy I might have put in a bid for that if it didn t look like it had been left out in the rain. It seems that AS/400 is not dead, there are cloud services available, here s one that provides a VM with 2GM of RAM for only EUR 251 monthly [1], wow. I m not qualified to comment on whether that s good value, but I think it s worth noting that a Linux VM running an AMD64 CPU with similar storage and the same RAM can be expected to cost about $10 per month. There is also a free AS/400 cloud named pub400 [2], this is the type of thing I d do if I had my own AS/400.

30 November 2021

Russell Coker: Links November 2021

The Guardian has an amusing article by Sophie Elmhirst about Libertarians buying a cruise ship to make a seasteading project off the coast of Panama [1]. It turns out that you need permits etc to do this and maintaining a ship is expensive. Also you wouldn t want to mine cryptocurrency in a ship cabin as most cabins are small and don t have enough airconditioning to remain pleasant if you dump 1kW or more into the air. NPR has an interesting article about the reaction of the NRA to the Columbine shootings [2]. Seems that some NRA person isn t a total asshole and is sharing their private information, maybe they are dying and are worried about going to hell. David Brin wrote an insightful blog post about the singleton hypothesis where he covers some of the evidence of autocratic societies failing [3]. I think he makes a convincing point about a single centralised government for human society not being viable. But something like the EU on a world wide scale could work well. Ken Shirriff wrote an interesting blog post about reverse engineering the Yamaha DX7 synthesiser [4]. The New York Times has an interesting article about a Baboon troop that became less aggressive after the alpha males all died at once from tuberculosis [5]. They established a new more peaceful culture that has outlived the beta males who avoided tuberculosis. The Guardian has an interesting article about how sequencing the genomes of the entire population can save healthcare costs while improving the health of the population [6]. This is somthing wealthy countries should offer for free to the world population. At a bit under $1000 per test that s only about $7 trillion to test everyone, and of course the price should drop significantly if there were billions of tests being done. The Strategy Bridge has an interesting article about SciFi books that have useful portrayals of military strategy [7]. The co-author is Major General Mick Ryan of the Australian Army which is noteworthy as Major General is the second highest rank in use by the Australian Army at this time. Vice has an interesting article about the co-evolution of penises and vaginas and how a lot of that evolution is based on avoiding impregnation from rape [8]. Cory Doctorow wrote an insightful Medium article about the way that governments could force interoperability through purchasing power [9]. Cory Doctorow wrote an insightful article for Locus Magazine about imagining life after capitalism and how capitalism might be replaced [10]. We need a Star Trek future! Arstechnica has an informative article about new developmenet in the rowhammer category of security attacks on DRAM [11]. It seems that DDR4 with ECC is the best current mitigation technique and that DDR3 with ECC is harder to attack than non-ECC RAM. So the thing to do is use ECC on all workstations and avoid doing security critical things on laptops because they can t juse ECC RAM.

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