Search Results: "ema"

21 June 2025

Ravi Dwivedi: Getting Brunei visa

In December 2024, my friend Badri and I were planning a trip to Southeast Asia. At this point, we were planning to visit Singapore, Malaysia and Vietnam. My Singapore visa had already been approved, and Malaysia was visa-free for us. For Vietnam, we had to apply for an e-visa online. We considered adding Brunei to our itinerary. I saw some videos of the Brunei visa process and got the impression that we needed to go to the Brunei embassy in Kuching, Malaysia in person. However, when I happened to search for Brunei on Organic Maps1, I stumbled upon the Brunei Embassy in Delhi. It seemed to be somewhere in Hauz Khas. As I was going to Delhi to collect my Singapore visa the next day, I figured I d also visit the Brunei Embassy to get information about the visa process. The next day I went to the location displayed by Organic Maps. It was next to the embassy of Madagascar, and a sign on the road divider confirmed that I was at the right place. That said, it actually looked like someone s apartment. I entered and asked for directions to the Brunei embassy, but the people inside did not seem to understand my query. After some back and forth, I realized that the embassy wasn t there. I now searched for the Brunei embassy on the Internet, and this time I got an address in Vasant Vihar. It seemed like the embassy had been moved from Hauz Khas to Vasant Vihar. Going by the timings mentioned on the web page, the embassy was closing in an hour. I took a Metro from Hauz Khas to Vasant Vihar. After deboarding at the Vasant Vihar metro station, I took an auto to reach the embassy. The address listed on the webpage got me into the correct block. However, the embassy was still nowhere to be seen. I asked around, but security guards in that area pointed me to the Burundi embassy instead. After some more looking around, I did end up finding the embassy. I spoke to the security guards at the gate and told them that I would like to know the visa process. They dialled a number and asked that person to tell me the visa process. I spoke to a lady on the phone. She listed the documents required for the visa process and mentioned that the timings for visa application were from 9 o clock to 11 o clock in the morning. She also informed me that the visa fees was 1000. I also asked about the process Badri, who lives far away in Tamil Nadu and cannot report at the embassy physically. She told me that I can submit a visa application on his behalf, along with an authorization letter. Having found the embassy in Delhi was a huge relief. The other plan - going to Kuching, Malaysia - was a bit uncertain, and we didn t know how much time it would take. Getting our passport submitted at an embassy in a foreign country was also not ideal. A few days later, Badri sent me all the documents required for his visa. I went to the embassy and submitted both the applications. The lady who collected our visa submissions asked me for our flight reservations from Delhi to Brunei, whereas ours were (keeping with our itinerary) from Kuala Lampur. She said that she might contact me later if it was required. For reference, here is the list of documents we submitted - I then asked about the procedure to collect the passports and visa results. Usually, embassies will tell you that they will contact you when they have decided on your applications. However, here I was informed that if they don t contact me within 5 days, I can come and collect our passports and visa result between 13:30-14:30 hours on the fifth day. That was strange :) I did visit the embassy to collect our visa results on the fifth day. However, the lady scolded me for not bringing the receipt she gave me. I was afraid that I might have to go all the way back home and bring the receipt to get our passports. The travel date was close, and it would take some time for Badri to receive his passport via courier as well. Fortunately, she gave me our passports (with the visa attached) and asked me to share a scanned copy of the receipt via email after I get home. We were elated that our visas were approved. Now we could focus on booking our flights. If you are going to Brunei, remember to fill their arrival card from the website within 48 hours of your arrival! Thanks to Badri and Contrapunctus for reviewing the draft before publishing the article.

  1. Nowadays, I prefer using Comaps instead of Organic Maps and recommend you do the same. Organic Maps had some issues with its governance and the community issues weren t being addressed.

19 June 2025

Debian Outreach Team: GSoC 2025 Introduction: Make Debian for Raspberry Pi Build Again

Hello everyone! I am Kurva Prashanth, Interested in the lower level working of system software, CPUs/SoCs and Hardware design. I was introduced to Open Hardware and Embedded Linux while studying electronics and embedded systems as part of robotics coursework. Initially, I did not pay much attention to it and quickly moved on. However, a short talk on Liberating SBCs using Debian by Yuvraj at MiniDebConf India, 2021 caught my interest. The talk focused on Open Hardware platforms such as Olimex and BeagleBone Black, as well as the Debian distributions tailored for these ARM-based single-board computers has intrigued me to delve deeper into the realm of Open Hardware and Embedded Linux. These days I m trying to improve my abilities to contribute to Debian and Linux Kernel development. Before finding out about the Google Summer of Code project, I had already started my journey with Debian. I extensively used Debian system build tools(debootstrap, sbuild, deb-build-pkg, qemu-debootstrap) for Building Debian Image for Bela Cape a real-time OS for music making to achieve extremely fast audio and sensor processing times. In 2023, I had the opportunity to attend DebConf23 in Kochi, India - thanks to Nilesh Patra (@nilesh) and I met Hector Oron (@zumbi) over dinner at DebConf23 and It was nice talking about his contributions/work at Debian on armhf port and Debian System Administration that conversation got me interested in knowing more about Debian ARM, Installer and I found it fascinating that EmDebian was once a external project bringing Debian to embedded systems and now, Debian itself can be run on many embedded systems. And, also during DebCamp I got Introduced to PGP/GPG keys and the web of trust by Carlos Henrique Lima Melara (@charles) I learned how to use and generate GPG keys. After DebConf23 I tried debian packaging and I miserably failed to get sponsorship for a python library I packaged. I came across the Debian project for this year s Google Summer of Code and found the project titled Make Debian for Raspberry Pi Build Again quite interesting to me and applied. Gladly, on May 8th, I received an acceptance e-mail from GSoC. I got excited that I ll spend the summer working on something that I like doing. I am thrilled to be part of this project and I am super excited for the summer of 25. I m looking forward to work on what I most like, new connections and learning opportunities. So, let me talk a bit more about my project. I will be working on to Make Debian for Raspberry Pi SBC s under the guidance of Gunnar Wolf (@gwolf). In this post, I will describe the project I will be working on.

Why make Debian for Raspberry Pi build again? There is an available set of images for running Debian in Raspberry Pi computers (all models below the 5 series)! However, the maintainer severely lacking time to take care for them; called for help for somebody to adopt them, but have not been successful. The image generation scripts might have bitrotted a bit, but it is mostly all done. And there is a lot of interest and use still in having the images freshly generated and decently tested! This GSoC project is about getting the [https://raspi.debian.net/ Raspberry Pi Debian images] site working reliably, daily-built images become automatic again and ideally making it easily deployable to be run in project machines and migrating exsisting hosting infrastructure to Debian.

How much it differ from Debian build process? While the goal is to stay as close as possible to the Debian build process, Raspberry Pi boards require some necessary platform-specific changes primarily in the early boot sequence and firmware handling. Unlike typical Debian systems, Raspberry Pi boards depend on a non-standard bootloader and use non-free firmware (raspi-firmware), Introducing some hardware-specific differences in the initialization process. These differences are largely confined to the early boot and hardware initialization stages. Once the system boots, the userspace remains closely aligned with a typical Debian install, using Debian packages. The current modifications are required due to non-free firmware. However, several areas merit review: but there are a few parts that might be worth changing.
  1. Boot flow: Transitioning to a U-Boot based boot process (as used in Debian installer images for many other SBCs) would reduce divergence and better align with Debian Installer.
  2. Current scripts/workarounds: Some existing hacks may now be redundant with recent upstream support and could be removed.
  3. Board-specific images: Shift to architecture-specific base images with runtime detection could simplify builds and reduce duplication.
Debian already already building SD card images for a wide range of SBCs (e.g., BeagleBone, BananaPi, OLinuXino, Cubieboard, etc.) installer-arm64/images/u-boot and installer-armhf/images/u-boot, a similar approach for Raspberry Pi could improve maintainability and consistency with Debian s broader SBC support.

Quoted from Mail Discussion Thread with Mentor (Gunnar Wolf)
"One direction we wanted to explore was whether we should still be building one image per family, or whether we could instead switch to one image per architecture (armel, armhf, arm64). There were some details to iron out as RPi3 and RPi4 were quite different, but I think it will be similar to the differences between the RPi 0 and 1, which are handled at first-boot time. To understand what differs between families, take a look at Cyril Brulebois generate-recipe (in the repo), which is a great improvement over the ugly mess I had before he contributed it"
In this project, I intend to to build one image per architecture (armel, armhf, arm64) rather than continuing with the current model of building one image per board. This change simplifies image management, reduces redundancy, and leverages dynamic configuration at boot time to support all supported boards within each architecture. By using U-Boot and flash-kernel, we can detect the board type and configure kernel parameters, DTBs, and firmware during the first boot, reducing duplication across images and simplifying the maintenance burden and we can also generalize image creation while still supporting board-specific behavior at runtime. This method aligns with existing practices in the DebianInstaller team and aligns with Debian s long-term maintainability goals and better leverages upstream capabilities, ensuring a consistent and scalable boot experience. To streamline and standardize the process of building bootable Debian images for Raspberry Pi devices, I proposed a new workflow that leverages U-Boot and flash-kernel Debian packages. This provides a clean, maintainable, and reproducible way to generate images for armel, armhf and arm64 boards. The workflow is vmdb2, a lightweight, declarative tool designed to automate the creation of disk images. A typical vmdb2 recipe defines the disk layout, base system installation (via debootstrap), architecture-specific packages, and any custom post-install hooks and the image should includes U-Boot (the u-boot-rpi package), flash-kernel, and a suitable Debian kernel package like linux-image-arm64 or linux-image-armmp. U-Boot serves as the platform s bootloader and is responsible for loading the kernel and initramfs. Unlike Raspberry Pi s non-free firmware/proprietary bootloader, U-Boot provides an open and scriptable interface, allowing us to follow a more standard Debian boot process. It can be configured to boot using either an extlinux.conf or a boot.scr script generated automatically by flash-kernel. The role of flash-kernel is to bridge Debian s kernel installation system with the specifics of embedded bootloaders like U-Boot. When installed, it automatically copies the kernel image, initrd, and device tree blobs (DTBs) to the /boot partition. It also generates the necessary boot.scr script if the board configuration demands it. To work correctly, flash-kernel requires that the target machine be identified via /etc/flash-kernel/machine, which must correspond to an entry in its internal machine database.\ Once the vmdb2 build is complete, the resulting image will contain a fully configured bootable system with all necessary boot components correctly installed. The image can be flashed to an SD card and used to boot on the intended device without additional manual configuration. Because all key packages (U-Boot, kernel, flash-kernel) are managed through Debian s package system, kernel updates and boot script regeneration are handled automatically during system upgrades.

Current Workflow: Builds one Image per family The current vmdb2 recipe uses the Raspberry Pi GPU bootloader provided via the raspi-firmware package. This is the traditional boot process followed by Raspberry Pi OS, and it s tightly coupled with firmware files like bootcode.bin, start.elf, and fixup.dat. These files are installed to /boot/firmware, which is mounted from a FAT32 partition labeled RASPIFIRM. The device tree files (*.dtb) are manually copied from /usr/lib/linux-image-*-arm64/broadcom/ into this partition. The kernel is installed via the linux-image-arm64 package, and the boot arguments are injected by modifying /boot/firmware/cmdline.txt using sed commands. Booting depends on the root partition being labeled RASPIROOT, referenced through that file. There is no bootloader like UEFI-based or U-Boot involved the Raspberry Pi firmware directly loads the kernel, which is standard for Raspberry Pi boards.
- apt: install
  packages:
    ...
    - raspi-firmware  
The boot partition contents and kernel boot setup are tightly controlled via scripting in the recipe. Limitations of Current Workflow: While this setup works, it is
  1. Proprietary and Raspberry Pi specific It relies on the closed-source GPU bootloader the raspi-firmware package, which is tightly coupled to specific Raspberry Pi models.
  2. Manual DTB handling Device tree files are manually copied and hardcoded, making upgrades or board-specific changes error-prone.
  3. Not easily extendable to future Raspberry Pi boards Any change in bootloader behavior (as seen in the Raspberry Pi 5, which introduces a more flexible firmware boot process) would require significant rework.
  4. No UEFI-based/U-Boot The current method bypasses the standard bootloader layers, making it inconsistent with other Debian ARM platforms and harder to maintain long-term.
As Raspberry Pi firmware and boot processes evolve, especially with the introduction of Pi 5 and potentially Pi 6, maintaining compatibility will require more flexibility - something best delivered by adopting U-Boot and flash-kernel.

New Workflow: Building Architecture-Specific Images with vmdb2, U-Boot, flash-kernel, and Debian Kernel This workflow outlines an improved approach to generating bootable Debian images architecture specific, using vmdb2, U-Boot, flash-kernel, and Debian kernels and also to move away from Raspberry Pi s proprietary bootloader to a fully open-source boot process which improves maintainability, consistency, and cross-board support.

New Method: Shift to U-Boot + flash-kernel U-Boot (via Debian su-boot-rpi package) and flash-kernel bring the image building process closer to how Debian officially boots ARM devices. flash-kernel integrates with the system s initramfs and kernel packages to install bootloaders, prepare boot.scr or extlinux.conf, and copy kernel/initrd/DTBs to /boot in a format that U-Boot expects. U-Boot will be used as a second-stage bootloader, loaded by the Raspberry Pi s built-in firmware. Once U-Boot is in place, it will read standard boot scripts ( boot.scr) generated by flash-kernel, providing a Debian-compatible and board-flexible solution. Extending YAML spec for vmdb2 build with U-Boot and flash-kernel To improve an existing vmdb2 YAML spec(https://salsa.debian.org/raspi-team/image-specs/raspi_master.yaml), to integrate U-Boot, flash-kernel, and the architecture-specific Debian kernel into the image build process. By incorporating u-boot-rpi and flash-kernel from Debian packages, alongside the standard initramfs-tools, we align the image closer to Debian best practices while supporting both armhf and arm64 architectures. Below are key additions and adjustments needed in a vmdb2 YAML spec to support the workflow: Install U-Boot, flash-kernel, initramfs-tools and the architecture-specific Debian kernel.
- apt: install
  packages:
    - u-boot-rpi
    - flash-kernel
    - initramfs-tools
    - linux-image-arm64 # or linux-image-armmp for armhf 
  tag: tag-root
Replace linux-image-arm64 with the correct kernel package for specific target architecture. These packages should be added under the tag-root section in YAML spec for vmdb2 build recipe. This ensures that the necessary bootloader, kernel, and initramfs tools are included and properly configured in the image. Configure Raspberry Pi firmware to Load U-Boot Install the U-Boot binary as kernel.img in /boot/firmware we can also download and build U-Boot from source, but Debian provides tested binaries.
- shell:  
    cp /usr/lib/u-boot/rpi_4/u-boot.bin $ ROOT? /boot/firmware/kernel.img
    echo "enable_uart=1" >> $ ROOT? /boot/firmware/config.txt
  root-fs: tag-root
This makes the RPi firmware load u-boot.bin instead of the Linux kernel directly. Set Up flash-kernel for Debian-style Boot flash-kernel integrates with initramfs-tools and writes boot config suitable for U-Boot. We need to make sure /etc/flash-kernel/db contains an entry for board (most Raspberry Pi boards already supported in Bookworm). Set up /etc/flash-kernel.conf with:
- create-file: /etc/flash-kernel.conf
  contents:  
    MACHINE="Raspberry Pi 4"
    BOOTPART="/dev/disk/by-label/RASPIFIRM"
    ROOTPART="/dev/disk/by-label/RASPIROOT"
  unless: rootfs_unpacked
This allows flash-kernel to write an extlinux.conf or boot.scr into /boot/firmware. Clean up Proprietary/Non-Free Firmware Bootflow Remove the direct kernel loading flow:
- shell:  
    rm -f $ ROOT? /boot/firmware/vmlinuz*
    rm -f $ ROOT? /boot/firmware/initrd.img*
    rm -f $ ROOT? /boot/firmware/cmdline.txt
  root-fs: tag-root
Let U-Boot and flash-kernel manage kernel/initrd and boot parameters instead. Boot Flow After This Change
[SoC ROM] -> [start.elf] -> [U-Boot] -> [boot.scr] -> [Linux Kernel]
  1. This still depends on the Raspberry Pi firmware to start, but it only loads U-Boot, not Linux kernel.
  2. U-Boot gives you more flexibility (e.g., networking, boot menus, signed boot).
  3. Using flash-kernel ensures kernel updates are handled the Debian Installer way.
  4. Test with a serial console (enable_uart=1) in case HDMI doesn t show early boot logs.
Advantage of New Workflow
  1. Replaces the proprietary Raspberry Pi bootloader with upstream U-Boot.
  2. Debian-native tooling Uses flash-kernel and initramfs-tools to manage boot configuration.
  3. Consistent across boards Works for both armhf and arm64, unifying the image build process.
  4. Easier to support new boards Like the Raspberry Pi 5 and future models.
This transition will standardize a bit image-building process, making it aligned with upstream Debian Installer workflows.

vmdb2 configuration for arm64 using u-boot and flash-kernel NOTE: This is a baseline example and may require tuning.
# Raspberry Pi arm64 image using U-Boot and flash-kernel
steps:
  # ... (existing mkimg, partitions, mount, debootstrap, etc.) ...
  # Install U-Boot, flash-kernel, initramfs-tools and architecture specific kernel
  - apt: install
    packages:
      - u-boot-rpi
      - flash-kernel
      - initramfs-tools
      - linux - image - arm64 # or linux - image - armmp for armhf
    tag: tag-root
  # Install U-Boot binary as kernel.img in firmware partition
  - shell:  
      cp /usr/lib/u-boot/rpi_arm64 /u-boot.bin $ ROOT? /boot/firmware/kernel.img
      echo "enable_uart=1" >> $ ROOT? /boot/firmware/config.txt
    root-fs: tag-root
  # Configure flash-kernel for Raspberry Pi
  - create-file: /etc/flash-kernel.conf
    contents:  
      MACHINE="Generic Raspberry Pi ARM64"
      BOOTPART="/dev/disk/by-label/RASPIFIRM"
      ROOTPART="/dev/disk/by-label/RASPIROOT"
    unless: rootfs_unpacked
  # Remove direct kernel boot files from Raspberry Pi firmware
  - shell:  
      rm -f $ ROOT? /boot/firmware/vmlinuz*
      rm -f $ ROOT? /boot/firmware/initrd.img*
      rm -f $ ROOT? /boot/firmware/cmdline.txt
    root-fs: tag-root
  # flash-kernel will manage boot scripts and extlinux.conf
  # Rest of image build continues...

Required Changes to Support Raspberry Pi Boards in Debian (flash-kernel + U-Boot)

Overview of Required Changes
Component Required Task
Debian U-Boot Package Add build target for rpi_arm64 in u-boot-rpi. Optionally deprecate legacy 32-bit targets.
Debian flash-kernel Package Add or verify entries in db/all.db for Pi 4, Pi 5, Zero 2W, CM4. Ensure boot script generation works via bootscr.uboot-generic.
Debian Kernel Ensure DTBs are installed at /usr/lib/linux-image-<version>/ and available for flash-kernel to reference.

flash-kernel

Already Supported Boards in flash-kernel Debian Package https://sources.debian.org/src/flash-kernel/3.109/db/all.db/#L1700
Model Arch DTB-Id
Raspberry Pi 1 A/B/B+, Rev2 armel bcm2835-*
Raspberry Pi CM1 armel bcm2835-rpi-cm1-io1.dtb
Raspberry Pi Zero/Zero W armel bcm2835-rpi-zero*.dtb
Raspberry Pi 2B armhf bcm2836-rpi-2-b.dtb
Raspberry Pi 3B/3B+ arm64 bcm2837-*
Raspberry Pi CM3 arm64 bcm2837-rpi-cm3-io3.dtb
Raspberry Pi 400 arm64 bcm2711-rpi-400.dtb

uboot

Already Supported Boards in Debian U-Boot Package https://salsa.debian.org/installer-team/flash-kernel/-/blob/master/db/all.db

arm64 Model Arch Upstream Defconfig Debian Target - - - Raspberry Pi 3B arm64 rpi_3_defconfig rpi_3 Raspberry Pi 4B arm64 rpi_4_defconfig rpi_4 Raspberry Pi 3B/3B+/CM3/CM3+/4B/CM4/400/5B/Zero 2W arm64 rpi_arm64_defconfig rpi_arm64
armhf Model Arch Upstream Defconfig Debian Target - - - Raspberry Pi 2 armhf rpi_2_defconfig rpi_2 Raspberry Pi 3B (32-bit) armhf rpi_3_32b_defconfig rpi_3_32b Raspberry Pi 4B (32-bit) armhf rpi_4_32b_defconfig rpi_4_32b
armel Model Arch Upstream Defconfig Debian Target - - - Raspberry Pi armel rpi_defconfig rpi Raspberry Pi 1/Zero armel rpi_0_w rpi_0_w These boards are already defined in debian/rules under the u-boot-rpi source package and generates usable U-Boot binaries for corresponding Raspberry Pi models.

To-Do: Add Missing Board Support to U-Boot and flash-kernel in Debian Several Raspberry Pi models are missing from the Debian U-Boot and flash-kernel packages, even though upstream support and DTBs exist in the Debian kernel but are missing entries in the flash-kernel database to enable support for bootloader installation and initrd handling.

Boards Not Yet Supported in flash-kernel Debian Package
Model Arch DTB-Id
Raspberry Pi 3A+ (32 & 64 bit) armhf, arm64 bcm2837-rpi-3-a-plus.dtb
Raspberry Pi 4B (32 & 64 bit) armhf, arm64 bcm2711-rpi-4-b.dtb
Raspberry Pi CM4 arm64 bcm2711-rpi-cm4-io.dtb
Raspberry Pi CM 4S arm64 -
Raspberry Zero 2 W arm64 bcm2710-rpi-zero-2-w.dtb
Raspberry Pi 5 arm64 bcm2712-rpi-5-b.dtb
Raspberry Pi CM5 arm64 -
Raspberry Pi 500 arm64 -

Boards Not Yet Supported in Debian U-Boot Package
Model Arch Upstream defconfig(s)
Raspberry Pi 3A+/3B+ arm64 -, rpi_3_b_plus_defconfig
Raspberry Pi CM 4S arm64 -
Raspberry Pi 5 arm64 -
Raspberry Pi CM5 arm64 -
Raspberry Pi 500 arm64 -

So, what next? During the Community Bonding Period, I got hands-on with workflow improvements, set up test environments, and began reviewing Raspberry Pi support in Debian s U-Boot and flash-kernel and these are the logs of the project, where I provide weekly reports on the work done. You can check here: Community Bonding Period logs. My next steps include submitting patches to the u-boot and flash-kernel packages to ensure all missing Raspberry Pi entries are built and shipped. And, also to confirm the kernel DTB installation paths and make sure the necessary files are included for all Raspberry Pi variants. Finally, plan to validate changes with test builds on Raspberry Pi hardware. In parallel, I m organizing my tasks and setting up my environment to contribute more effectively. It s been exciting to explore how things work under the hood and to prepare for a summer of learning and contributing to this great community.

18 June 2025

Sergio Durigan Junior: GCC, glibc, stack unwinding and relocations A war story

I ve been meaning to write a post about this bug for a while, so here it is (before I forget the details!). First, I d like to thank a few people: I ll probably forget some details because it s been more than a week (and life at $DAYJOB moves fast), but we ll see.

The background story Wolfi OS takes security seriously, and one of the things we have is a package which sets the hardening compiler flags for C/C++ according to the best practices recommended by OpenSSF. At the time of this writing, these flags are (in GCC s spec file parlance):
*self_spec:
+ % !O:% !O1:% !O2:% !O3:% !O0:% !Os:% !0fast:% !0g:% !0z:-O2  -fhardened -Wno-error=hardened -Wno-hardened % !fdelete-null-pointer-checks:-fno-delete-null-pointer-checks  -fno-strict-overflow -fno-strict-aliasing % !fomit-frame-pointer:-fno-omit-frame-pointer  -mno-omit-leaf-frame-pointer
*link:
+ --as-needed -O1 --sort-common -z noexecstack -z relro -z now
The important part for our bug is the usage of -z now and -fno-strict-aliasing. As I was saying, these flags are set for almost every build, but sometimes things don t work as they should and we need to disable them. Unfortunately, one of these problematic cases has been glibc. There was an attempt to enable hardening while building glibc, but that introduced a strange breakage to several of our packages and had to be reverted. Things stayed pretty much the same until a few weeks ago, when I started working on one of my roadmap items: figure out why hardening glibc wasn t working, and get it to work as much as possible.

Reproducing the bug I started off by trying to reproduce the problem. It s important to mention this because I often see young engineers forgetting to check if the problem is even valid anymore. I don t blame them; the anxiety to get the bug fixed can be really blinding. Fortunately, I already had one simple test to trigger the failure. All I had to do was install the py3-matplotlib package and then invoke:
$ python3 -c 'import matplotlib'
This would result in an abortion with a coredump. I followed the steps above, and readily saw the problem manifesting again. OK, first step is done; I wasn t getting out easily from this one.

Initial debug The next step is to actually try to debug the failure. In an ideal world you get lucky and are able to spot what s wrong after just a few minutes. Or even better: you also can devise a patch to fix the bug and contribute it to upstream. I installed GDB, and then ran the py3-matplotlib command inside it. When the abortion happened, I issued a backtrace command inside GDB to see where exactly things had gone wrong. I got a stack trace similar to the following:
#0  0x00007c43afe9972c in __pthread_kill_implementation () from /lib/libc.so.6
#1  0x00007c43afe3d8be in raise () from /lib/libc.so.6
#2  0x00007c43afe2531f in abort () from /lib/libc.so.6
#3  0x00007c43af84f79d in uw_init_context_1[cold] () from /usr/lib/libgcc_s.so.1
#4  0x00007c43af86d4d8 in _Unwind_RaiseException () from /usr/lib/libgcc_s.so.1
#5  0x00007c43acac9014 in __cxxabiv1::__cxa_throw (obj=0x5b7d7f52fab0, tinfo=0x7c429b6fd218 <typeinfo for pybind11::attribute_error>, dest=0x7c429b5f7f70 <pybind11::reference_cast_error::~reference_cast_error() [clone .lto_priv.0]>)
    at ../../../../libstdc++-v3/libsupc++/eh_throw.cc:93
#6  0x00007c429b5ec3a7 in ft2font__getattr__(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) [clone .lto_priv.0] [clone .cold] () from /usr/lib/python3.13/site-packages/matplotlib/ft2font.cpython-313-x86_64-linux-gnu.so
#7  0x00007c429b62f086 in pybind11::cpp_function::initialize<pybind11::object (*&)(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >), pybind11::object, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, pybind11::name, pybind11::scope, pybind11::sibling>(pybind11::object (*&)(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >), pybind11::object (*)(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >), pybind11::name const&, pybind11::scope const&, pybind11::sibling const&):: lambda(pybind11::detail::function_call&)#1 ::_FUN(pybind11::detail::function_call&) [clone .lto_priv.0] ()
   from /usr/lib/python3.13/site-packages/matplotlib/ft2font.cpython-313-x86_64-linux-gnu.so
#8  0x00007c429b603886 in pybind11::cpp_function::dispatcher(_object*, _object*, _object*) () from /usr/lib/python3.13/site-packages/matplotlib/ft2font.cpython-313-x86_64-linux-gnu.so
...
Huh. Initially this didn t provide me with much information. There was something strange seeing the abort function being called right after _Unwind_RaiseException, but at the time I didn t pay much attention to it. OK, time to expand our horizons a little. Remember when I said that several of our packages would crash with a hardened glibc? I decided to look for another problematic package so that I could make it crash and get its stack trace. My thinking here is that maybe if I can compare both traces, something will come up. I happened to find an old discussion where Dann Frazier mentioned that Emacs was also crashing for him. He and I share the Emacs passion, and I totally agreed with him when he said that Emacs crashing is priority -1! (I m paraphrasing). I installed Emacs, ran it, and voil : the crash happened again. OK, that was good. When I ran Emacs inside GDB and asked for a backtrace, here s what I got:
#0  0x00007eede329972c in __pthread_kill_implementation () from /lib/libc.so.6
#1  0x00007eede323d8be in raise () from /lib/libc.so.6
#2  0x00007eede322531f in abort () from /lib/libc.so.6
#3  0x00007eede262879d in uw_init_context_1[cold] () from /usr/lib/libgcc_s.so.1
#4  0x00007eede2646e7c in _Unwind_Backtrace () from /usr/lib/libgcc_s.so.1
#5  0x00007eede3327b11 in backtrace () from /lib/libc.so.6
#6  0x000059535963a8a1 in emacs_backtrace ()
#7  0x000059535956499a in main ()
Ah, this backtrace is much simpler to follow. Nice. Hmmm. Now the crash is happening inside _Unwind_Backtrace. A pattern emerges! This must have something to do with stack unwinding (or so I thought keep reading to discover the whole truth). You see, the backtrace function (yes, it s a function) and C++ s exception handling mechanism use similar techniques to do their jobs, and it pretty much boils down to unwinding frames from the stack. I looked into Emacs source code, specifically the emacs_backtrace function, but could not find anything strange over there. This bug was probably not going to be an easy fix

The quest for a minimal reproducer Being able to easily reproduce the bug is awesome and really helps with debugging, but even better is being able to have a minimal reproducer for the problem. You see, py3-matplotlib is a huge package and pulls in a bunch of extra dependencies, so it s not easy to ask other people to just install this big package plus these other dependencies, and then run this command , especially if we have to file an upstream bug and talk to people who may not even run the distribution we re using. So I set up to try and come up with a smaller recipe to reproduce the issue, ideally something that s not tied to a specific package from the distribution. Having all the information gathered from the initial debug session, especially the Emacs backtrace, I thought that I could write a very simple program that just invoked the backtrace function from glibc in order to trigger the code path that leads to _Unwind_Backtrace. Here s what I wrote:
#include <execinfo.h>

int
main(int argc, char *argv[])
 
  void *a[4096];
  backtrace (a, 100);
  return 0;
 
After compiling it, I determined that yes, the problem did happen with this small program as well. There was only a small nuisance: the manifestation of the bug was not deterministic, so I had to execute the program a few times until it crashed. But that s much better than what I had before, and a small price to pay. Having a minimal reproducer pretty much allows us to switch our focus to what really matters. I wouldn t need to dive into Emacs or Python s source code anymore. At the time, I was sure this was a glibc bug. But then something else happened.

GCC 15 I had to stop my investigation efforts because something more important came up: it was time to upload GCC 15 to Wolfi. I spent a couple of weeks working on this (it involved rebuilding the whole archive, filing hundreds of FTBFS bugs, patching some programs, etc.), and by the end of it the transition went smooth. When the GCC 15 upload was finally done, I switched my focus back to the glibc hardening problem. The first thing I did was to yes, reproduce the bug again. It had been a few weeks since I had touched the package, after all. So I built a hardened glibc with the latest GCC and the bug did not happen anymore! Fortunately, the very first thing I thought was this must be GCC , so I rebuilt the hardened glibc with GCC 14, and the bug was there again. Huh, unexpected but very interesting.

Diving into glibc and libgcc At this point, I was ready to start some serious debugging. And then I got a message on Signal. It was one of those moments where two minds think alike: Gabriel decided to check how I was doing, and I was thinking about him because this involved glibc, and Gabriel contributed to the project for many years. I explained what I was doing, and he promptly offered to help. Yes, there are more people who love low level debugging! We spent several hours going through disassembles of certain functions (because we didn t have any debug information in the beginning), trying to make sense of what we were seeing. There was some heavy GDB involved; unfortunately I completely lost the session s history because it was done inside a container running inside an ephemeral VM. But we learned a lot. For example:
  • It was hard to actually understand the full stack trace leading to uw_init_context_1[cold]. _Unwind_Backtrace obviously didn t call it (it called uw_init_context_1, but what was that [cold] doing?). We had to investigate the disassemble of uw_init_context_1 in order to determined where uw_init_context_1[cold] was being called.
  • The [cold] suffix is a GCC function attribute that can be used to tell the compiler that the function is unlikely to be reached. When I read that, my mind immediately jumped to this must be an assertion , so I went to the source code and found the spot.
  • We were able to determine that the return code of uw_frame_state_for was 5, which means _URC_END_OF_STACK. That s why the assertion was triggering.
After finding these facts without debug information, I decided to bite the bullet and recompiled GCC 14 with -O0 -g3, so that we could debug what uw_frame_state_for was doing. After banging our heads a bit more, we found that fde is NULL at this excerpt:
// ...
  fde = _Unwind_Find_FDE (context->ra + _Unwind_IsSignalFrame (context) - 1,
                          &context->bases);
  if (fde == NULL)
     
#ifdef MD_FALLBACK_FRAME_STATE_FOR
      /* Couldn't find frame unwind info for this function.  Try a
         target-specific fallback mechanism.  This will necessarily
         not provide a personality routine or LSDA.  */
      return MD_FALLBACK_FRAME_STATE_FOR (context, fs);
#else
      return _URC_END_OF_STACK;
#endif
     
// ...
We re debugging on amd64, which means that MD_FALLBACK_FRAME_STATE_FOR is defined and therefore is called. But that s not really important for our case here, because we had established before that _Unwind_Find_FDE would never return NULL when using a non-hardened glibc (or a glibc compiled with GCC 15). So we decided to look into what _Unwind_Find_FDE did. The function is complex because it deals with .eh_frame , but we were able to pinpoint the exact location where find_fde_tail (one of the functions called by _Unwind_Find_FDE) is returning NULL:
if (pc < table[0].initial_loc + data_base)
  return NULL;
We looked at the addresses of pc and table[0].initial_loc + data_base, and found that the former fell within libgcc s text section, which the latter fell within /lib/ld-linux-x86-64.so.2 text. At this point, we were already too tired to continue. I decided to keep looking at the problem later and see if I could get any further.

Bisecting GCC The next day, I woke up determined to find what changed in GCC 15 that caused the bug to disappear. Unless you know GCC s internals like they are your own home (which I definitely don t), the best way to do that is to git bisect the commits between GCC 14 and 15. I spent a few days running the bisect. It took me more time than I d have liked to find the right range of commits to pass git bisect (because of how branches and tags are done in GCC s repository), and I also had to write some helper scripts that:
  • Modified the gcc.yaml package definition to make it build with the commit being bisected.
  • Built glibc using the GCC that was just built.
  • Ran tests inside a docker container (with the recently built glibc installed) to determine whether the bug was present.
At the end, I had a commit to point to:
commit 99b1daae18c095d6c94d32efb77442838e11cbfb
Author: Richard Biener <rguenther@suse.de>
Date:   Fri May 3 14:04:41 2024 +0200
    tree-optimization/114589 - remove profile based sink heuristics
Makes sense, right?! No? Well, it didn t for me either. Even after reading what was changed in the code and the upstream bug fixed by the commit, I was still clueless as to why this change fixed the problem (I say fixed because it may very well be an unintended consequence of the change, and some other problem might have been introduced).

Upstream takes over After obtaining the commit that possibly fixed the bug, while talking to Dann and explaining what I did, he suggested that I should file an upstream bug and check with them. Great idea, of course. I filed the following upstream bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120653 It s a bit long, very dense and complex, but ultimately upstream was able to find the real problem and have a patch accepted in just two days. Nothing like knowing the code base. The initial bug became: https://sourceware.org/bugzilla/show_bug.cgi?id=33088 In the end, the problem was indeed in how the linker defines __ehdr_start, which, according to the code (from elf/dl-support.c):
if (_dl_phdr == NULL)
   
    /* Starting from binutils-2.23, the linker will define the
       magic symbol __ehdr_start to point to our own ELF header
       if it is visible in a segment that also includes the phdrs.
       So we can set up _dl_phdr and _dl_phnum even without any
       information from auxv.  */


    extern const ElfW(Ehdr) __ehdr_start attribute_hidden;
    assert (__ehdr_start.e_phentsize == sizeof *GL(dl_phdr));
    _dl_phdr = (const void *) &__ehdr_start + __ehdr_start.e_phoff;
    _dl_phnum = __ehdr_start.e_phnum;
   
But the following definition is the problematic one (from elf/rtld.c):
extern const ElfW(Ehdr) __ehdr_start attribute_hidden;
This symbol (along with its counterpart, __ehdr_end) was being run-time relocated when it shouldn t be. The fix that was pushed added optimization barriers to prevent the compiler from doing the relocations. I don t claim to fully understand what was done here, and Jakub s analysis is a thing to behold, but in the end I was able to confirm that the patch fixed the bug. And in the end, it was indeed a glibc bug.

Conclusion This was an awesome bug to investigate. It s one of those that deserve a blog post, even though some of the final details of the fix flew over my head. I d like to start blogging more about these sort of bugs, because I ve encountered my fair share of them throughout my career. And it was great being able to do some debugging with another person, exchange ideas, learn things together, and ultimately share that deep satisfaction when we find why a crash is happening. I have at least one more bug in my TODO list to write about (another one with glibc, but this time I was able to get to the end of it and come up with a patch). Stay tunned. P.S.: After having published the post I realized that I forgot to explain why the -z now and -fno-strict-aliasing flags were important. -z now is the flag that I determined to be the root cause of the breakage. If I compiled glibc with every hardening flag except -z now, everything worked. So initially I thought that the problem had to do with how ld.so was resolving symbols at runtime. As it turns out, this ended up being more a symptom than the real cause of the bug. As for -fno-strict-aliasing, a Gentoo developer who commented on the GCC bug above mentioned that this OpenSSF bug had a good point against using this flag for hardening. I still have to do a deep dive on what was discussed in the issue, but this is certainly something to take into consideration. There s this very good write-up about strict aliasing in general if you re interested in understanding it better.

17 June 2025

Evgeni Golov: Arguing with an AI or how Evgeni tried to use CodeRabbit

Everybody is trying out AI assistants these days, so I figured I'd jump on that train and see how fast it derails. I went with CodeRabbit because I've seen it on YouTube ads work, I guess. I am trying to answer the following questions: To reduce the amount of output and not to confuse contributors, CodeRabbit was configured to only do reviews on demand. What follows is a rather unscientific evaluation of CodeRabbit based on PRs in two Foreman-related repositories, looking at the summaries CodeRabbit posted as well as the comments/suggestions it had about the code. Ansible 2.19 support PR: theforeman/foreman-ansible-modules#1848 summary posted The summary CodeRabbit posted is technically correct.
This update introduces several changes across CI configuration, Ansible roles, plugins, and test playbooks. It expands CI test coverage to a new Ansible version, adjusts YAML key types in test variables, refines conditional logic in Ansible tasks, adds new default variables, and improves clarity and consistency in playbook task definitions and debug output.
Yeah, it does all of that, all right. But it kinda misses the point that the addition here is "Ansible 2.19 support", which starts with adding it to the CI matrix and then adjusting the code to actually work with that version. Also, the changes are not for "clarity" or "consistency", they are fixing bugs in the code that the older Ansible versions accepted, but the new one is more strict about. Then it adds a table with the changed files and what changed in there. To me, as the author, it felt redundant, and IMHO doesn't add any clarity to understand the changes. (And yes, same "clarity" vs bugfix mistake here, but that makes sense as it apparently miss-identified the change reason) And then the sequence diagrams They probably help if you have a dedicated change to a library or a library consumer, but for this PR it's just noise, especially as it only covers two of the changes (addition of 2.19 to the test matrix and a change to the inventory plugin), completely ignoring other important parts. Overall verdict: noise, don't need this. comments posted CodeRabbit also posted 4 comments/suggestions to the changes. Guard against undefined result.task IMHO a valid suggestion, even if on the picky side as I am not sure how to make it undefined here. I ended up implementing it, even if with slightly different (and IMHO better readable) syntax. Inconsistent pipeline in when for composite CV versions That one was funny! The original complaint was that the when condition used slightly different data manipulation than the data that was passed when the condition was true. The code was supposed to do "clean up the data, but only if there are any items left after removing the first 5, as we always want to keep 5 items". And I do agree with the analysis that it's badly maintainable code. But the suggested fix was to re-use the data in the variable we later use for performing the cleanup. While this is (to my surprise!) valid Ansible syntax, it didn't make the code much more readable as you need to go and look at the variable definition. The better suggestion then came from Ewoud: to compare the length of the data with the number we want to keep. Humans, so smart! But Ansible is not Ewoud's native turf, so he asked whether there is a more elegant way to count how much data we have than to use list count in Jinja (the data comes from a Python generator, so needs to be converted to a list first). And the AI helpfully suggested to use count instead! However, count is just an alias for length in Jinja, so it behaves identically and needs a list. Luckily the AI quickly apologized for being wrong after being pointed at the Jinja source and didn't try to waste my time any further. Wouldn't I have known about the count alias, we'd have committed that suggestion and let CI fail before reverting again. Apply the same fix for non-composite CV versions The very same complaint was posted a few lines later, as the logic there is very similar just slightly different data to be filtered and cleaned up. Interestingly, here the suggestion also was to use the variable. But there is no variable with the data! The text actually says one need to "define" it, yet the "committable suggestion" doesn't contain that part. Interestingly, when asked where it sees the "inconsistency" in that hunk, it said the inconsistency is with the composite case above. That however is nonsense, as while we want to keep the same number of composite and non-composite CV versions, the data used in the task is different it even gets consumed by a totally different playbook so there can't be any real consistency between the branches. I ended up applying the same logic as suggested by Ewoud above. As that refactoring was possible in a consistent way. Ensure consistent naming for Oracle Linux subscription defaults One of the changes in Ansible 2.19 is that Ansible fails when there are undefined variables, even if they are only undefined for cases where they are unused. CodeRabbit complains that the names of the defaults I added are inconsistent. And that is technically correct. But those names are already used in other places in the code, so I'd have to refactor more to make it work properly. Once being pointed at the fact that the variables already exist, the AI is as usual quick to apologize, yay. add new parameters to the repository module PR: theforeman/foreman-ansible-modules#1860 summary posted Again, the summary is technically correct
The repository module was updated to support additional parameters for repository synchronization and authentication. New options were added for ansible collections, ostree, Python packages, and yum repositories, including authentication tokens, filtering controls, and version retention settings. All changes were limited to module documentation and argument specification.
But it doesn't add anything you'd not get from looking at the diff, especially as it contains a large documentation chunk explaining those parameters. No sequence diagram this time. That's a good thing! Overall verdict: noise (even if the amount is small), don't need this. comments posted CodeRabbit generated two comments for this PR. Interestingly, none of them overlapped with the issues ansible-lint and friends found. get rid of the FIXMEs Yepp, that's fair add validation for the new parameters Yepp, I forgot these (not intentionally!). The diff it suggests is nonsense, as it doesn't take into account the existing Ansible and Yum validations, but it clearly has read them as the style etc of the new ones matches. It also managed to group the parameters correctly by repository type, so it's something.
 if module.foreman_params['content_type'] != 'ansible_collection':
     invalid_list = [key for key in ['ansible_collection_requirements'] if key in module.foreman_params]
     if invalid_list:
         module.fail_json(msg="( 0 ) can only be used with content_type 'ansible_collection'".format(",".join(invalid_list)))
+
+# Validate ansible_collection specific parameters
+if module.foreman_params['content_type'] != 'ansible_collection':
+    invalid_list = [key for key in ['ansible_collection_auth_token', 'ansible_collection_auth_url'] if key in module.foreman_params]
+    if invalid_list:
+        module.fail_json(msg="( 0 ) can only be used with content_type 'ansible_collection'".format(",".join(invalid_list)))
+
+# Validate ostree specific parameters
+if module.foreman_params['content_type'] != 'ostree':
+    invalid_list = [key for key in ['depth', 'exclude_refs', 'include_refs'] if key in module.foreman_params]
+    if invalid_list:
+        module.fail_json(msg="( 0 ) can only be used with content_type 'ostree'".format(",".join(invalid_list)))
+
+# Validate python package specific parameters
+if module.foreman_params['content_type'] != 'python':
+    invalid_list = [key for key in ['excludes', 'includes', 'package_types', 'keep_latest_packages'] if key in module.foreman_params]
+    if invalid_list:
+        module.fail_json(msg="( 0 ) can only be used with content_type 'python'".format(",".join(invalid_list)))
+
+# Validate yum specific parameter
+if module.foreman_params['content_type'] != 'yum' and 'upstream_authentication_token' in module.foreman_params:
+    module.fail_json(msg="upstream_authentication_token can only be used with content_type 'yum'")
Interestingly, it also said "Note: If 'python' is not a valid content_type, please adjust the validation accordingly." which is quite a hint at a bug in itself. The module currently does not even allow to create content_type=python repositories. That should have been more prominent, as it's a BUG! parameter persistence in obsah PR: theforeman/obsah#72 summary posted Mostly correct. It did miss-interpret the change to a test playbook as an actual "behavior" change: "Introduced new playbook variables for database configuration" there is no database configuration in this repository, just the test playbook using the same metadata as a consumer of the library. Later on it does say "Playbook metadata and test fixtures", so unclear whether this is a miss-interpretation or just badly summarized. As long as you also look at the diff, it won't confuse you, but if you're using the summary as the sole source of information (bad!) it would. This time the sequence diagram is actually useful, yay. Again, not 100% accurate: it's missing the fact that saving the parameters is hidden behind an "if enabled" flag something it did represent correctly for loading them. Overall verdict: not really useful, don't need this. comments posted Here I was a bit surprised, especially as the nitpicks were useful! Persist-path should respect per-user state locations (nitpick) My original code used os.environ.get('OBSAH_PERSIST_PATH', '/var/lib/obsah/parameters.yaml') for the location of the persistence file. CodeRabbit correctly pointed out that this won't work for non-root users and one should respect XDG_STATE_HOME. Ewoud did point that out in his own review, so I am not sure whether CodeRabbit came up with this on its own, or also took the human comments into account. The suggested code seems fine too just doesn't use /var/lib/obsah at all anymore. This might be a good idea for the generic library we're working on here, and then be overridden to a static /var/lib path in a consumer (which always runs as root). In the end I did not implement it, but mostly because I was lazy and was sure we'd override it anyway. Positional parameters are silently excluded from persistence (nitpick) The library allows you to generate both positional (foo without --) and non-positional (--foo) parameters, but the code I wrote would only ever persist non-positional parameters. This was intentional, but there is no documentation of the intent in a comment which the rabbit thought would be worth pointing out. It's a fair nitpick and I ended up adding a comment. Enforce FQDN validation for database_host The library has a way to perform type checking on passed parameters, and one of the supported types is "FQDN" so a fully qualified domain name, with dots and stuff. The test playbook I added has a database_host variable, but I didn't bother adding a type to it, as I don't really need any type checking here. While using "FQDN" might be a bit too strict here technically a working database connection can also use a non-qualified name or an IP address, I was positively surprised by this suggestion. It shows that the rest of the repository was taken into context when preparing the suggestion. reset_args() can raise AttributeError when a key is absent This is a correct finding, the code is not written in a way that would survive if it tries to reset things that are not set. However, that's only true for the case where users pass in --reset-<parameter> without ever having set parameter before. The complaint about the part where the parameter is part of the persisted set but not in the parsed args is wrong as parsed args inherit from the persisted set. The suggested code is not well readable, so I ended up fixing it slightly differently. Persisted values bypass argparse type validation When persisting, I just yaml.safe_dump the parsed parameters, which means the YAML will contain native types like integers. The argparse documentation warns that the type checking argparse does only applies to strings and is skipped if you pass anything else (via default values). While correct, it doesn't really hurt here as the persisting only happens after the values were type-checked. So there is not really a reason to type-check them again. Well, unless the type changes, anyway. Not sure what I'll do with this comment. consider using contextlib.suppress This was added when I asked CodeRabbit for a re-review after pushing some changes. Interestingly, the PR already contained try: except: pass code before, and it did not flag that. Also, the code suggestion contained import contextlib in the middle of the code, instead in the head of the file. Who would do that?! But the comment as such was valid, so I fixed it in all places it is applicable, not only the one the rabbit found. workaround to ensure LCE and CV are always sent together PR: theforeman/foreman-ansible-modules#1867 summary posted
A workaround was added to the _update_entity method in the ForemanAnsibleModule class to ensure that when updating a host, both content_view_id and lifecycle_environment_id are always included together in the update payload. This prevents partial updates that could cause inconsistencies.
Partial updates are not a thing. The workaround is purely for the fact that Katello expects both parameters to be sent, even if only one of them needs an actual update. No diagram, good. Overall verdict: misleading summaries are bad! comments posted Given a small patch, there was only one comment. Implementation looks correct, but consider adding error handling for robustness. This reads correct on the first glance. More error handling is always better, right? But if you dig into the argumentation, you see it's wrong. Either: The AI accepted defeat once I asked it to analyze things in more detail, but why did I have to ask in the first place?! Summary Well, idk, really. Did the AI find things that humans did not find (or didn't bother to mention)? Yes. It's debatable whether these were useful (see e.g. the database_host example), but I tend to be in the "better to nitpick/suggest more and dismiss than oversee" team, so IMHO a positive win. Did the AI output help the humans with the review (useful summary etc)? In my opinion it did not. The summaries were either "lots of words, no real value" or plain wrong. The sequence diagrams were not useful either. Luckily all of that can be turned off in the settings, which is what I'd do if I'd continue using it. Did the AI output help the humans with the code (useful suggestions etc)? While the actual patches it posted were "meh" at best, there were useful findings that resulted in improvements to the code. Was the AI output misleading? Absolutely! The whole Jinja discussion would have been easier without the AI "help". Same applies for the "error handling" in the workaround PR. Was the AI output distracting? The output is certainly a lot, so yes I think it can be distracting. As mentioned, I think dropping the summaries can make the experience less distracting. What does all that mean? I will disable the summaries for the repositories, but will leave the @coderabbitai review trigger active if someone wants an AI-assisted review. This won't be something that I'll force on our contributors and maintainers, but they surely can use it if they want. But I don't think I'll be using this myself on a regular basis. Yes, it can be made "usable". But so can be vim ;-) Also, I'd prefer to have a junior human asking all the questions and making bad suggestions, so they can learn from it, and not some planet burning machine.

Matthew Garrett: Locally hosting an internet-connected server

I'm lucky enough to have a weird niche ISP available to me, so I'm paying $35 a month for around 600MBit symmetric data. Unfortunately they don't offer static IP addresses to residential customers, and nor do they allow multiple IP addresses per connection, and I'm the sort of person who'd like to run a bunch of stuff myself, so I've been looking for ways to manage this.

What I've ended up doing is renting a cheap VPS from a vendor that lets me add multiple IP addresses for minimal extra cost. The precise nature of the VPS isn't relevant - you just want a machine (it doesn't need much CPU, RAM, or storage) that has multiple world routeable IPv4 addresses associated with it and has no port blocks on incoming traffic. Ideally it's geographically local and peers with your ISP in order to reduce additional latency, but that's a nice to have rather than a requirement.

By setting that up you now have multiple real-world IP addresses that people can get to. How do we get them to the machine in your house you want to be accessible? First we need a connection between that machine and your VPS, and the easiest approach here is Wireguard. We only need a point-to-point link, nothing routable, and none of the IP addresses involved need to have anything to do with any of the rest of your network. So, on your local machine you want something like:

[Interface]
PrivateKey = privkeyhere
ListenPort = 51820
Address = localaddr/32

[Peer]
Endpoint = VPS:51820
PublicKey = pubkeyhere
AllowedIPs = VPS/0


And on your VPS, something like:

[Interface]
Address = vpswgaddr/32
SaveConfig = true
ListenPort = 51820
PrivateKey = privkeyhere

[Peer]
PublicKey = pubkeyhere
AllowedIPs = localaddr/32


The addresses here are (other than the VPS address) arbitrary - but they do need to be consistent, otherwise Wireguard is going to be unhappy and your packets will not have a fun time. Bring that interface up with wg-quick and make sure the devices can ping each other. Hurrah! That's the easy bit.

Now you want packets from the outside world to get to your internal machine. Let's say the external IP address you're going to use for that machine is 321.985.520.309 and the wireguard address of your local system is 867.420.696.005. On the VPS, you're going to want to do:

iptables -t nat -A PREROUTING -p tcp -d 321.985.520.309 -j DNAT --to-destination 867.420.696.005

Now, all incoming packets for 321.985.520.309 will be rewritten to head towards 867.420.696.005 instead (make sure you've set net.ipv4.ip_forward to 1 via sysctl!). Victory! Or is it? Well, no.

What we're doing here is rewriting the destination address of the packets so instead of heading to an address associated with the VPS, they're now going to head to your internal system over the Wireguard link. Which is then going to ignore them, because the AllowedIPs statement in the config only allows packets coming from your VPS, and these packets still have their original source IP. We could rewrite the source IP to match the VPS IP, but then you'd have no idea where any of these packets were coming from, and that sucks. Let's do something better. On the local machine, in the peer, let's update AllowedIps to 0.0.0.0/0 to permit packets form any source to appear over our Wireguard link. But if we bring the interface up now, it'll try to route all traffic over the Wireguard link, which isn't what we want. So we'll add table = off to the interface stanza of the config to disable that, and now we can bring the interface up without breaking everything but still allowing packets to reach us. However, we do still need to tell the kernel how to reach the remote VPN endpoint, which we can do with ip route add vpswgaddr dev wg0. Add this to the interface stanza as:

PostUp = ip route add vpswgaddr dev wg0
PreDown = ip route del vpswgaddr dev wg0


That's half the battle. The problem is that they're going to show up there with the source address still set to the original source IP, and your internal system is (because Linux) going to notice it has the ability to just send replies to the outside world via your ISP rather than via Wireguard and nothing is going to work. Thanks, Linux. Thinux.

But there's a way to solve this - policy routing. Linux allows you to have multiple separate routing tables, and define policy that controls which routing table will be used for a given packet. First, let's define a new table reference. On the local machine, edit /etc/iproute2/rt_tables and add a new entry that's something like:

1 wireguard


where "1" is just a standin for a number not otherwise used there. Now edit your wireguard config and replace table=off with table=wireguard - Wireguard will now update the wireguard routing table rather than the global one. Now all we need to do is to tell the kernel to push packets into the appropriate routing table - we can do that with ip rule add from localaddr lookup wireguard, which tells the kernel to take any packet coming from our Wireguard address and push it via the Wireguard routing table. Add that to your Wireguard interface config as:

PostUp = ip rule add from localaddr lookup wireguard
PreDown = ip rule del from localaddr lookup wireguard

and now your local system is effectively on the internet.

You can do this for multiple systems - just configure additional Wireguard interfaces on the VPS and make sure they're all listening on different ports. If your local IP changes then your local machines will end up reconnecting to the VPS, but to the outside world their accessible IP address will remain the same. It's like having a real IP without the pain of convincing your ISP to give it to you.

comment count unavailable comments

16 June 2025

Paul Tagliamonte: The Promised LAN

The Internet has changed a lot in the last 40+ years. Fads have come and gone. Network protocols have been designed, deployed, adopted, and abandoned. Industries have come and gone. The types of people on the internet have changed a lot. The number of people on the internet has changed a lot, creating an information medium unlike anything ever seen before in human history. There s a lot of good things about the Internet as of 2025, but there s also an inescapable hole in what it used to be, for me. I miss being able to throw a site up to send around to friends to play with without worrying about hordes of AI-feeding HTML combine harvesters DoS-ing my website, costing me thousands in network transfer for the privilege. I miss being able to put a lightly authenticated game server up and not worry too much at night wondering if that process is now mining bitcoin. I miss being able to run a server in my home closet. Decades of cat and mouse games have rendered running a mail server nearly impossible. Those who are brave enough to try are met with weekslong stretches of delivery failures and countless hours yelling ineffectually into a pipe that leads from the cheerful lobby of some disinterested corporation directly into a void somewhere 4 layers below ground level. I miss the spirit of curiosity, exploration, and trying new things. I miss building things for fun without having to worry about being too successful, after which security offices start demanding my supplier paperwork in triplicate as heartfelt thanks from their engineering teams. I miss communities that are run because it is important to them, not for ad revenue. I miss community operated spaces and having more than four websites that are all full of nothing except screenshots of each other. Every other page I find myself on now has an AI generated click-bait title, shared for rage-clicks all brought-to-you-by-our-sponsors completely covered wall-to-wall with popup modals, telling me how much they respect my privacy, with the real content hidden at the bottom bracketed by deceptive ads served by companies that definitely know which new coffee shop I went to last month. This is wrong, and those who have seen what was know it. I can t keep doing it. I m not doing it any more. I reject the notion that this is as it needs to be. It is wrong. The hole left in what the Internet used to be must be filled. I will fill it.

What comes before part b? Throughout the 2000s, some of my favorite memories were from LAN parties at my friends places. Dragging your setup somewhere, long nights playing games, goofing off, even building software all night to get something working being able to do something fiercely technical in the context of a uniquely social activity. It wasn t really much about the games or the projects it was an excuse to spend time together, just hanging out. A huge reason I learned so much in college was that campus was a non-stop LAN party we could freely stand up servers, talk between dorms on the LAN, and hit my dorm room computer from the lab. Things could go from individual to social in the matter of seconds. The Internet used to work this way my dorm had public IPs handed out by DHCP, and my workstation could serve traffic from anywhere on the internet. I haven t been back to campus in a few years, but I d be surprised if this were still the case. In December of 2021, three of us got together and connected our houses together in what we now call The Promised LAN. The idea is simple fill the hole we feel is gone from our lives. Build our own always-on 24/7 nonstop LAN party. Build a space that is intrinsically social, even though we re doing technical things. We can freely host insecure game servers or one-off side projects without worrying about what someone will do with it. Over the years, it s evolved very slowly we haven t pulled any all-nighters. Our mantra has become old growth , building each layer carefully. As of May 2025, the LAN is now 19 friends running around 25 network segments. Those 25 networks are connected to 3 backbone nodes, exchanging routes and IP traffic for the LAN. We refer to the set of backbone operators as The Bureau of LAN Management . Combined decades of operating critical infrastructure has driven The Bureau to make a set of well-understood, boring, predictable, interoperable and easily debuggable decisions to make this all happen. Nothing here is exotic or even technically interesting.

Applications of trusting trust The hardest part, however, is rejecting the idea that anything outside our own LAN is untrustworthy nearly irreversible damage inflicted on us by the Internet. We have solved this by not solving it. We strictly control membership the absolute hard minimum for joining the LAN requires 10 years of friendship with at least one member of the Bureau, with another 10 years of friendship planned. Members of the LAN can veto new members even if all other criteria is met. Even with those strict rules, there s no shortage of friends that meet the qualifications but we are not equipped to take that many folks on. It s hard to join -both socially and technically. Doing something malicious on the LAN requires a lot of highly technical effort upfront, and it would endanger a decade of friendship. We have relied on those human, social, interpersonal bonds to bring us all together. It s worked for the last 4 years, and it should continue working until we think of something better. We assume roommates, partners, kids, and visitors all have access to The Promised LAN. If they re let into our friends' network, there is a level of trust that works transitively for us I trust them to be on mine. This LAN is not for security , rather, the network border is a social one. Benign hacking in the original sense of misusing systems to do fun and interesting things is encouraged. Robust ACLs and firewalls on the LAN are, by definition, an interpersonal not technical failure. We all trust every other network operator to run their segment in a way that aligns with our collective values and norms. Over the last 4 years, we ve grown our own culture and fads around half of the people on the LAN have thermal receipt printers with open access, for printing out quips or jokes on each other s counters. It s incredible how much network transport and a trusting culture gets you there s a 3-node IRC network, exotic hardware to gawk at, radios galore, a NAS storage swap, LAN only email, and even a SIP phone network of redphones .

DIY We do not wish to, nor will we, rebuild the internet. We do not wish to, nor will we, scale this. We will never be friends with enough people, as hard as we may try. Participation hinges on us all having fun. As a result, membership will never be open, and we will never have enough connected LANs to deal with the technical and social problems that start to happen with scale. This is a feature, not a bug. This is a call for you to do the same. Build your own LAN. Connect it with friends homes. Remember what is missing from your life, and fill it in. Use software you know how to operate and get it running. Build slowly. Build your community. Do it with joy. Remember how we got here. Rebuild a community space that doesn t need to be mediated by faceless corporations and ad revenue. Build something sustainable that brings you joy. Rebuild something you use daily. Bring back what we re missing.

11 June 2025

Iustin Pop: This blog finally goes git-annex!

A long, long time ago I have a few pictures on this blog, mostly in earlier years, because even with small pictures, the git repository became 80MiB soon this is not much in absolute terms, but the actual Markdown/Haskell/CSS/HTML total size is tiny compared to the picture, PDFs and fonts. I realised I need a better solution, probably about ten years ago, and that I should investigate git-annex. Then time passed, and I heard about git-lfs, so I thought that s the way forward. Now, I recently got interested again into doing something about this repository, and started researching.

Detour: git-lfs I was sure that git-lfs, being supported by large providers, would be the modern solution. But to my surprise, git-lfs is very server centric, which in hindsight makes sense, but for a home setup, it s not very good. Maybe I misunderstood, but git-lfs is more a protocol/method for a forge to store files, rather than an end-user solution. But then you need to backup those files separately (together with the rest of the forge), or implement another way of safeguarding them. Further details such as the fact that it keeps two copies of the files (one in the actual checked-out tree, one in internal storage) means it s not a good solution. Well, for my blog yes, but not in general. Then posts on Reddit about horror stories people being locked out of github due to quota, as an example, or this Stack Overflow post about git-lfs constraining how one uses git, convinced me that s not what I want. To each their own, but not for me I might want to push this blog s repo to github, but I definitely wouldn t want in that case to pay for github storage for my blog images (which are copies, not originals). And yes, even in 2025, those quotas are real GitHub limits and I agree with GitHub, storage and large bandwidth can t be free.

Back to the future: git-annex So back to git-annex. I thought it s going to be a simple thing, but oh boy, was I wrong. It took me half a week of continuous (well, in free time) reading and discussions with LLMs to understand a bit how it works. I think, honestly, it s a bit too complex, which is why the workflows page lists seven (!) levels of workflow complexity, from fully-managed, to fully-manual. IMHO, respect to the author for the awesome tool, but if you need a web app to help you manage git, it hints that the tool is too complex. I made the mistake of running git annex sync once, to realise it actually starts pushing to my upstream repo and creating new branches and whatnot, so after enough reading, I settled on workflow 6/7, since I don t want another tool to manage my git history. Maybe I m an outlier here, but everything automatic is a bit too much for me. Once you do managed yourself how git-annex works (on the surface, at least), it is a pretty cool thing. It uses a git-annex git branch to store metainformation, and that is relatively clean. If you do run git annex sync, it creates some extra branches, which I don t like, but meh.

Trick question: what is a remote? One of the most confusing things about git-annex was understanding its remote concept. I thought a remote is a place where you replicate your data. But not, that s a special remote. A normal remote is a git remote, but which is expected to be git/ssh/with command line access. So if you have a git+ssh remote, git-annex will not only try to push it s above-mentioned branch, but also copy the files. If such a remote is on a forge that doesn t support git-annex, then it will complain and get confused. Of course, if you read the extensive docs, you just do git config remote.<name>.annex-ignore true, and it will understand that it should not sync to it. But, aside, from this case, git-annex expects that all checkouts and clones of the repository are both metadata and data. And if you do any annex commands in them, all other clones will know about them! This can be unexpected, and you find people complaining about it, but nowadays there s a solution:
git clone   dir && cd dir
git config annex.private true
git annex init "temp copy"
This is important. Any leaf git clone must be followed by that annex.private true config, especially on CI/CD machines. Honestly, I don t understand why by default clones should be official data stores, but it is what it is. I settled on not making any of my checkouts stable , but only the actual storage places. Except those are not git repositories, but just git-annex storage things. I.e., special remotes. Is it confusing enough yet ?

Special remotes The special remotes, as said, is what I expected to be the normal git annex remotes, i.e. places where the data is stored. But well, they exist, and while I m only using a couple simple ones, there is a large number of them. Among the interesting ones: git-lfs, a remote that allows also storing the git repository itself (git-remote-annex), although I m bit confused about this one, and most of the common storage providers via the rclone remote. Plus, all of the special remotes support encryption, so this is a really neat way to store your files across a large number of things, and handle replication, number of copies, from which copy to retrieve, etc. as you with.

And many of other features git-annex has tons of other features, so to some extent, the sky s the limit. Automatic selection of what to add git it vs plain git, encryption handling, number of copies, clusters, computed files, etc. etc. etc. I still think it s cool but too complex, though!

Uses Aside from my blog post, of course. I ve seen blog posts/comments about people using git-annex to track/store their photo collection, and I could see very well how the remote encrypted repos any of the services supported by rclone could be an N+2 copy or so. For me, tracking photos would be a bit too tedious, but it could maybe work after more research. A more practical thing would probably be replicating my local movie collection (all legal, to be clear) better than just run rsync from time to time and tracking the large files in it via git-annex. That s an exercise for another day, though, once I get more mileage with it - my blog pictures are copies, so I don t care much if they get lost, but movies are primary online copies, and I don t want to re-dump the discs. Anyway, for later.

Migrating to git-annex Migrating here means ending in a state where all large files are in git-annex, and the plain git repo is small. Just moving the files to git annex at the current head doesn t remove them from history, so your git repository is still large; it won t grow in the future, but remains with old size (and contains the large files in its history). In my mind, a nice migration would be: run a custom command, and all the history is migrated to git-annex, so I can go back in time and the still use git-annex. I na vely expected this would be easy and already available, only to find comments on the git-annex site with unsure git-filter-branch calls and some web discussions. This is the discussion on the git annex website, but it didn t make me confident it would do the right thing. But that discussion is now 8 years old. Surely in 2025, with git-filter-repo, it s easier? And, maybe I m missing something, but it is not. Not from the point of view of plain git, that s easy, but because interacting with git-annex, which stores its data in git itself, so doing this properly across successive steps of a repo (when replaying the commits) is, I think, not well defined behaviour. So I was stuck here for a few days, until I got an epiphany: As I m going to rewrite the repository, of course I m keeping a copy of it from before git-annex. If so, I don t need the history, back in time, to be correct in the sense of being able to retrieve the binary files too. It just needs to be correct from the point of view of the actual Markdown and Haskell files that represent the meat of the blog. This simplified the problem a lot. At first, I wanted to just skip these files, but this could also drop commits (git-filter-repo, by default, drops the commits if they re empty), and removing the files loses information - when they were added, what were the paths, etc. So instead I came up with a rather clever idea, if I might say so: since git-annex replaces files with symlinks already, just replace the files with symlinks in the whole history, except symlinks that are dangling (to represent the fact that files are missing). One could also use empty files, but empty files are more valid in a sense than dangling symlinks, hence why I settled on those. Doing this with git-filter-repo is easy, in newer versions, with the new --file-info-callback. Here is the simple code I used:
import os
import os.path
import pathlib

SKIP_EXTENSIONS= 'jpg', 'jpeg', 'png', 'pdf', 'woff', 'woff2' 
FILE_MODES =  b"100644", b"100755" 
SYMLINK_MODE = b"120000"

fas_string = filename.decode()
path = pathlib.PurePosixPath(fas_string)
ext = path.suffix.removeprefix('.')

if ext not in SKIP_EXTENSIONS:
  return (filename, mode, blob_id)

if mode not in FILE_MODES:
  return (filename, mode, blob_id)

print(f"Replacing ' filename ' (extension '. ext ') in  os.getcwd() ")

symlink_target = '/none/binary-file-removed-from-git-history'.encode()
new_blob_id = value.insert_file_with_contents(symlink_target)
return (filename, SYMLINK_MODE, new_blob_id)
This goes and replaces files with a symlink to nowhere, but the symlink should explain why it s dangling. Then later renames or moving the files around work naturally , as the rename/mv doesn t care about file contents. Then, when the filtering is done via:
git-filter-repo --file-info-callback <(cat ~/filter-big.py ) --force
It is easy to onboard to git annex:
  • remove all dangling symlinks
  • copy the (binary) files from the original repository
  • since they re named the same, and in the same places, git sees a type change
  • then simply run git annex add on those files
For me it was easy as all such files were in a few directories, so just copying those directories back, a few git-annex add commands, and done. Of course, then adding a few rsync remotes, git annex copy --to, and the repository was ready. Well, I also found a bug in my own Hakyll setup: on a fresh clone, when the large files are just dangling symlinks, the builder doesn t complain, just ignores the images. Will have to fix.

Other resources This is a blog that I read at the beginning, and I found it very useful as an intro: https://switowski.com/blog/git-annex/. It didn t help me understand how it works under the covers, but it is well written. The author does use the sync command though, which is too magic for me, but also agrees about its complexity

The proof is in the pudding And now, for the actual first image to be added that never lived in the old plain git repository. It s not full-res/full-size, it s cropped a bit on the bottom. Earlier in the year, I went to Paris for a very brief work trip, and I walked around a bit it was more beautiful than what I remembered from way way back. So a bit random selection of a picture, but here it is:
Un bateau sur la Seine Un bateau sur la Seine
Enjoy!

Gunnar Wolf: Understanding Misunderstandings - Evaluating LLMs on Networking Questions

This post is a review for Computing Reviews for Understanding Misunderstandings - Evaluating LLMs on Networking Questions , a article published in Association for Computing Machinery (ACM), SIGCOMM Computer Communication Review
Large language models (LLMs) have awed the world, emerging as the fastest-growing application of all time ChatGPT reached 100 million active users in January 2023, just two months after its launch. After an initial cycle, they have gradually been mostly accepted and incorporated into various workflows, and their basic mechanics are no longer beyond the understanding of people with moderate computer literacy. Now, given that the technology is better understood, we face the question of how convenient LLM chatbots are for different occupations. This paper embarks on the question of whether LLMs can be useful for networking applications. This paper systematizes querying three popular LLMs (GPT-3.5, GPT-4, and Claude 3) with questions taken from several network management online courses and certifications, and presents a taxonomy of six axes along which the incorrect responses were classified: The authors also measure four strategies toward improving answers: The authors observe that, while some of those strategies were marginally useful, they sometimes resulted in degraded performance. The authors queried the commercially available instances of Gemini and GPT, which achieved scores over 90 percent for basic subjects but fared notably worse in topics that require understanding and converting between different numeric notations, such as working with Internet protocol (IP) addresses, even if they are trivial (that is, presenting the subnet mask for a given network address expressed as the typical IPv4 dotted-quad representation). As a last item in the paper, the authors compare performance with three popular open-source models: Llama3.1, Gemma2, and Mistral with their default settings. Although those models are almost 20 times smaller than the GPT-3.5 commercial model used, they reached comparable performance levels. Sadly, the paper does not delve deeper into these models, which can be deployed locally and adapted to specific scenarios. The paper is easy to read and does not require deep mathematical or AI-related knowledge. It presents a clear comparison along the described axes for the 503 multiple-choice questions presented. This paper can be used as a guide for structuring similar studies over different fields.

Freexian Collaborators: Debian Contributions: Updated Austin, DebConf 25 preparations continue and more! (by Anupa Ann Joseph)

Debian Contributions: 2025-05 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.

Updated Austin, by Colin Watson and Helmut Grohne Austin is a frame stack sampling profiler for Python. It allows profiling Python applications without instrumenting them while losing some accuracy in the process, and is the only one of its kind presently packaged for Debian. Unfortunately, it hadn t been uploaded in a while and hence the last Python version it worked with was 3.8. We updated it to a current version and also dealt with a number of architecture-specific problems (such as unintended sign promotion, 64bit time_t fallout and strictness due to -Wformat-security ) in cooperation with upstream. With luck, it will migrate in time for trixie.

Preparing for DebConf 25, by Stefano Rivera and Santiago Ruano Rinc n DebConf 25 is quickly approaching, and the organization work doesn t stop. In May, Stefano continued supporting the different teams. Just to give a couple of examples, Stefano made changes in DebConf 25 website to make BoF and sprints submissions public, so interested people can already know if a BoF or sprint for a given subject is planned, allowing coordination with the proposer; or to enhance how statistics are made public to help the work of the local team. Santiago has participated in different tasks, including the logistics of the conference, like preparing more information about the public transportation that will be available. Santiago has also taken part in activities related to fundraising and reviewing more event proposals.

Miscellaneous contributions
  • Lucas fixed security issues in Valkey in unstable.
  • Lucas tried to help with the update of Redis to version 8 in unstable. The package hadn t been updated for a while due to licensing issues, but now upstream maintainers fixed them.
  • Lucas uploaded around 20 ruby-* packages to unstable that weren t updated for some years to make them build reproducible. Thanks to reproducible builds folks to point out those issues. Also some unblock requests (and follow-ups) were needed to make them reach trixie in time for the release.
  • Lucas is organizing a Debian Outreach session for DebConf 25, reaching out to all interns of Google Summer of Code and Outreachy programs from the last year. The session will be presented by in-person interns and also video recordings from the interns interested in participating but did not manage to attend the conference.
  • Lucas continuously works on DebConf Content team tasks. Replying to speakers, sponsors, and communicating internally with the team.
  • Carles improved po-debconf-manager: fixed bugs reported by Catalan translator, added possibility to import packages out of salsa, added using non-default project branches on salsa, polish to get ready for DebCamp.
  • Carles tested new apt in trixie and reported bugs to apt , installation-report , libqt6widget6 .
  • Carles used po-debconf-manager and imported remaining 80 packages, reviewed 20 translations, submitted (MR or bugs) 54 translations.
  • Carles prepared some topics for translation BoF in DebConf (gathered feedback, first pass on topics).
  • Helmut gave an introductory talk about the mechanics of Linux namespaces at MiniDebConf Hamburg.
  • Helmut sent 25 patches for cross compilation failures.
  • Helmut reviewed, refined and applied a patch from Jochen Sprickerhof to make the Multi-Arch hinter emit more hints for pure Python modules.
  • Helmut sat down with Christoph Berg (not affiliated with Freexian) and extended unschroot to support directory-based chroots with overlayfs. This is a feature that was lost in transitioning from sbuild s schroot backend to its unshare backend. unschroot implements the schroot API just enough to be usable with sbuild and otherwise works a lot like the unshare backend. As a result, apt.postgresql.org now performs its builds contained in a user namespace.
  • Helmut looked into a fair number of rebootstrap failures most of which related to musl or gcc-15 and imported patches or workarounds to make those builds proceed.
  • Helmut updated dumat to use sqop fixing earlier PGP verification problems thanks to Justus Winter and Neal Walfield explaining a lot of sequoia at MiniDebConf Hamburg.
  • Helmut got the previous zutils update for /usr-move wrong again and had to send another update.
  • Helmut looked into why debvm s autopkgtests were flaky and with lots of help from Paul Gevers and Michael Tokarev tracked it down to a race condition in qemu. He updated debvm to trigger the problem less often and also fixed a wrong dependency using Luca Boccassi s patch.
  • Santiago continued the switch to sbuild for Salsa CI (that was stopped for some months), and has been mainly testing linux, since it s a complex project that heavily customizes the pipeline. Santiago is preparing the changes for linux to submit a MR soon.
  • In openssh, Colin tracked down some intermittent sshd crashes to a root cause, and issued bookworm and bullseye updates for CVE-2025-32728.
  • Colin spent some time fixing up fail2ban, mainly reverting a patch that caused its tests to fail and would have banned legitimate users in some common cases.
  • Colin backported upstream fixes for CVE-2025-48383 (django-select2) and CVE-2025-47287 (python-tornado) to unstable.
  • Stefano supported video streaming and recording for 2 miniDebConfs in May: Macei and Hamburg. These had overlapping streams for one day, which is a first for us.
  • Stefano packaged the new version of python-virtualenv that includes our patches for not including the wheel for wheel.
  • Stefano got all involved parties to agree (in principle) to meet at DebConf for a mediated discussion on a dispute that was brought to the technical committee.
  • Anupa coordinated the swag purchase for DebConf 25 with Juliana and Nattie.
  • Anupa joined the publicity team meeting for discussing the upcoming events and BoF at DebConf 25.
  • Anupa worked with the publicity team to publish Bits post to welcome GSoc 2025 Interns.

Freexian Collaborators: Monthly report about Debian Long Term Support, May 2025 (by Roberto C. S nchez)

Like each month, have a look at the work funded by Freexian s Debian LTS offering.

Debian LTS contributors In May, 22 contributors have been paid to work on Debian LTS, their reports are available:
  • Abhijith PA did 8.0h (out of 0.0h assigned and 8.0h from previous period).
  • Adrian Bunk did 26.0h (out of 26.0h assigned).
  • Andreas Henriksson did 1.0h (out of 15.0h assigned and 3.0h from previous period), thus carrying over 17.0h to the next month.
  • Andrej Shadura did 3.0h (out of 10.0h assigned), thus carrying over 7.0h to the next month.
  • Bastien Roucari s did 20.0h (out of 20.0h assigned).
  • Ben Hutchings did 8.0h (out of 20.0h assigned and 4.0h from previous period), thus carrying over 16.0h to the next month.
  • Carlos Henrique Lima Melara did 12.0h (out of 11.0h assigned and 1.0h from previous period).
  • Chris Lamb did 15.5h (out of 0.0h assigned and 15.5h from previous period).
  • Daniel Leidert did 25.0h (out of 26.0h assigned), thus carrying over 1.0h to the next month.
  • Emilio Pozuelo Monfort did 21.0h (out of 16.75h assigned and 11.0h from previous period), thus carrying over 6.75h to the next month.
  • Guilhem Moulin did 11.5h (out of 8.5h assigned and 6.5h from previous period), thus carrying over 3.5h to the next month.
  • Jochen Sprickerhof did 3.5h (out of 8.75h assigned and 17.5h from previous period), thus carrying over 22.75h to the next month.
  • Lee Garrett did 26.0h (out of 12.75h assigned and 13.25h from previous period).
  • Lucas Kanashiro did 20.0h (out of 18.0h assigned and 2.0h from previous period).
  • Markus Koschany did 20.0h (out of 26.25h assigned), thus carrying over 6.25h to the next month.
  • Roberto C. S nchez did 20.75h (out of 24.0h assigned), thus carrying over 3.25h to the next month.
  • Santiago Ruano Rinc n did 15.0h (out of 12.5h assigned and 2.5h from previous period).
  • Sean Whitton did 6.25h (out of 6.0h assigned and 2.0h from previous period), thus carrying over 1.75h to the next month.
  • Sylvain Beucler did 26.25h (out of 26.25h assigned).
  • Thorsten Alteholz did 15.0h (out of 15.0h assigned).
  • Tobias Frost did 12.0h (out of 12.0h assigned).
  • Utkarsh Gupta did 1.0h (out of 15.0h assigned), thus carrying over 14.0h to the next month.

Evolution of the situation In May, we released 54 DLAs. The LTS Team was particularly active in May, publishing a higher than normal number of advisories, as well as helping with a wide range of updates to packages in stable and unstable, plus some other interesting work. We are also pleased to welcome several updates from contributors outside the regular team.
  • Notable security updates:
    • containerd, prepared by Andreas Henriksson, fixes a vulnerability that could cause containers launched as non-root users to be run as root
    • libapache2-mod-auth-openidc, prepared by Moritz Schlarb, fixes a vulnerability which could allow an attacker to crash an Apache web server with libapache2-mod-auth-openidc installed
    • request-tracker4, prepared by Andrew Ruthven, fixes multiple vulnerabilities which could result in information disclosure, cross-site scripting and use of weak encryption for S/MIME emails
    • postgresql-13, prepared by Bastien Roucari s, fixes an application crash vulnerability that could affect the server or applications using libpq
    • dropbear, prepared by Guilhem Moulin, fixes a vulnerability which could potentially result in execution of arbitrary shell commands
    • openjdk-17, openjdk-11, prepared by Thorsten Glaser, fixes several vulnerabilities, which include denial of service, information disclosure or bypass of sandbox restrictions
    • glibc, prepared by Sean Whitton, fixes a privilege escalation vulnerability
  • Notable non-security updates:
    • wireless-regdb, prepared by Ben Hutchings, updates information reflecting changes to radio regulations in many countries
This month s contributions from outside the regular team include the libapache2-mod-auth-openidc update mentioned above, prepared by Moritz Schlarb (the maintainer of the package); the update of request-tracker4, prepared by Andrew Ruthven (the maintainer of the package); and the updates of openjdk-17 and openjdk-11, also noted above, prepared by Thorsten Glaser. Additionally, LTS Team members contributed stable updates of the following packages:
  • rubygems and yelp/yelp-xsl, prepared by Lucas Kanashiro
  • simplesamlphp, prepared by Tobias Frost
  • libbson-xs-perl, prepared by Roberto C. S nchez
  • fossil, prepared by Sylvain Beucler
  • setuptools and mydumper, prepared by Lee Garrett
  • redis and webpy, prepared by Adrian Bunk
  • xrdp, prepared by Abhijith PA
  • tcpdf, prepared by Santiago Ruano Rinc n
  • kmail-account-wizard, prepared by Thorsten Alteholz
Other contributions were also made by LTS Team members to packages in unstable:
  • proftpd-dfsg DEP-8 tests (autopkgtests) were provided to the maintainer, prepared by Lucas Kanashiro
  • a regular upload of libsoup2.4, prepared by Sean Whitton
  • a regular upload of setuptools, prepared by Lee Garrett
Freexian, the entity behind the management of the Debian LTS project, has been working for some time now on the development of an advanced CI platform for Debian-based distributions, called Debusine. Recently, Debusine has reached a level of feature implementation that makes it very usable. Some members of the LTS Team have been using Debusine informally, and during May LTS coordinator Santiago Ruano Rinc n has made a call for the team to help with testing of Debusine, and to help evaluate its suitability for the LTS Team to eventually begin using as the primary mechanism for uploading packages into Debian. Team members who have started using Debusine are providing valuable feedback to the Debusine development team, thus helping to improve the platform for all users. Actually, a number of updates, for both bullseye and bookworm, made during the month of May were handled using Debusine, e.g. rubygems s DLA-4163-1. By the way, if you are a Debian Developer, you can easily test Debusine following the instructions found at https://wiki.debian.org/DebusineDebianNet. DebConf, the annual Debian Conference, is coming up in July and, as is customary each year, the week preceding the conference will feature an event called DebCamp. The DebCamp week provides an opportunity for teams and other interested groups/individuals to meet together in person in the same venue as the conference itself, with the purpose of doing focused work, often called sprints . LTS coordinator Roberto C. S nchez has announced that the LTS Team is planning to hold a sprint primarily focused on the Debian security tracker and the associated tooling used by the LTS Team and the Debian Security Team.

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7 June 2025

Evgeni Golov: show your desk - 2025 edition

Back in 2020 I posted about my desk setup at home. Recently someone in our #remotees channel at work asked about WFH setups and given quite a few things changed in mine, I thought it's time to post an update. But first, a picture! standing desk with a monitor, laptop etc (Yes, it's cleaner than usual, how could you tell?!) desk It's still the same Flexispot E5B, no change here. After 7 years (I bought mine in 2018) it still works fine. If I'd have to buy a new one, I'd probably get a four-legged one for more stability (they got quite affordable now), but there is no immediate need for that. chair It's still the IKEA Volmar. Again, no complaints here. hardware Now here we finally have some updates! laptop A Lenovo ThinkPad X1 Carbon Gen 12, Intel Core Ultra 7 165U, 32GB RAM, running Fedora (42 at the moment). It's connected to a Lenovo ThinkPad Thunderbolt 4 Dock. It just works . workstation It's still the P410, but mostly unused these days. monitor An AOC U2790PQU 27" 4K. I'm running it at 150% scaling, which works quite decently these days (no comparison to when I got it). speakers As the new monitor didn't want to take the old Dell soundbar, I have upgraded to a pair of Alesis M1Active 330 USB. They sound good and were not too expensive. I had to fix the volume control after some time though. webcam It's still the Logitech C920 Pro. microphone The built in mic of the C920 is really fine, but to do conference-grade talks (and some podcasts ), I decided to get something better. I got a FIFINE K669B, with a nice arm. It's not a Shure, for sure, but does the job well and Christian was quite satisfied with the results when we recorded the Debian and Foreman specials of Focus on Linux. keyboard It's still the ThinkPad Compact USB Keyboard with TrackPoint. I had to print a few fixes and replacement parts for it, but otherwise it's doing great. Seems Lenovo stopped making those, so I really shouldn't break it any further. mouse Logitech MX Master 3S. The surface of the old MX Master 2 got very sticky at some point and it had to be replaced. other notepad I'm still terrible at remembering things, so I still write them down in an A5 notepad. whiteboard I've also added a (small) whiteboard on the wall right of the desk, mostly used for long term todo lists. coaster Turns out Xeon-based coasters are super stable, so it lives on! yubikey Yepp, still a thing. Still USB-A because... reasons. headphones Still the Bose QC25, by now on the third set of ear cushions, but otherwise working great and the odd 15 cushion replacement does not justify buying anything newer (which would have the same problem after some time, I guess). I did add a cheap (~10 ) Bluetooth-to-Headphonejack dongle, so I can use them with my phone too (shakes fist at modern phones). And I do use the headphones more in meetings, as the Alesis speakers fill the room more with sound and thus sometimes produce a bit of an echo. charger The Bose need AAA batteries, and so do some other gadgets in the house, so there is a technoline BC 700 charger for AA and AAA on my desk these days. light Yepp, I've added an IKEA Tertial and an ALDI "face" light. No, I don't use them much. KVM switch I've "built" a KVM switch out of an USB switch, but given I don't use the workstation that often these days, the switch is also mostly unused.

6 June 2025

Reproducible Builds: Reproducible Builds in May 2025

Welcome to our 5th report from the Reproducible Builds project in 2025! Our monthly reports outline what we ve been up to over the past month, and highlight items of news from elsewhere in the increasingly-important area of software supply-chain security. If you are interested in contributing to the Reproducible Builds project, please do visit the Contribute page on our website. In this report:
  1. Security audit of Reproducible Builds tools published
  2. When good pseudorandom numbers go bad
  3. Academic articles
  4. Distribution work
  5. diffoscope and disorderfs
  6. Website updates
  7. Reproducibility testing framework
  8. Upstream patches

Security audit of Reproducible Builds tools published The Open Technology Fund s (OTF) security partner Security Research Labs recently an conducted audit of some specific parts of tools developed by Reproducible Builds. This form of security audit, sometimes called a whitebox audit, is a form testing in which auditors have complete knowledge of the item being tested. They auditors assessed the various codebases for resilience against hacking, with key areas including differential report formats in diffoscope, common client web attacks, command injection, privilege management, hidden modifications in the build process and attack vectors that might enable denials of service. The audit focused on three core Reproducible Builds tools: diffoscope, a Python application that unpacks archives of files and directories and transforms their binary formats into human-readable form in order to compare them; strip-nondeterminism, a Perl program that improves reproducibility by stripping out non-deterministic information such as timestamps or other elements introduced during packaging; and reprotest, a Python application that builds source code multiple times in various environments in order to to test reproducibility. OTF s announcement contains more of an overview of the audit, and the full 24-page report is available in PDF form as well.

When good pseudorandom numbers go bad Danielle Navarro published an interesting and amusing article on their blog on When good pseudorandom numbers go bad. Danielle sets the stage as follows:
[Colleagues] approached me to talk about a reproducibility issue they d been having with some R code. They d been running simulations that rely on generating samples from a multivariate normal distribution, and despite doing the prudent thing and using set.seed() to control the state of the random number generator (RNG), the results were not computationally reproducible. The same code, executed on different machines, would produce different random numbers. The numbers weren t just a little bit different in the way that we ve all wearily learned to expect when you try to force computers to do mathematics. They were painfully, brutally, catastrophically, irreproducible different. Somewhere, somehow, something broke.
Thanks to David Wheeler for posting about this article on our mailing list

Academic articles There were two scholarly articles published this month that related to reproducibility: Daniel Hugenroth and Alastair R. Beresford of the University of Cambridge in the United Kingdom and Mario Lins and Ren Mayrhofer of Johannes Kepler University in Linz, Austria published an article titled Attestable builds: compiling verifiable binaries on untrusted systems using trusted execution environments. In their paper, they:
present attestable builds, a new paradigm to provide strong source-to-binary correspondence in software artifacts. We tackle the challenge of opaque build pipelines that disconnect the trust between source code, which can be understood and audited, and the final binary artifact, which is difficult to inspect. Our system uses modern trusted execution environments (TEEs) and sandboxed build containers to provide strong guarantees that a given artifact was correctly built from a specific source code snapshot. As such it complements existing approaches like reproducible builds which typically require time-intensive modifications to existing build configurations and dependencies, and require independent parties to continuously build and verify artifacts.
The authors compare attestable builds with reproducible builds by noting an attestable build requires only minimal changes to an existing project, and offers nearly instantaneous verification of the correspondence between a given binary and the source code and build pipeline used to construct it , and proceed by determining that t he overhead (42 seconds start-up latency and 14% increase in build duration) is small in comparison to the overall build time.
Timo Pohl, Pavel Nov k, Marc Ohm and Michael Meier have published a paper called Towards Reproducibility for Software Packages in Scripting Language Ecosystems. The authors note that past research into Reproducible Builds has focused primarily on compiled languages and their ecosystems, with a further emphasis on Linux distribution packages:
However, the popular scripting language ecosystems potentially face unique issues given the systematic difference in distributed artifacts. This Systemization of Knowledge (SoK) [paper] provides an overview of existing research, aiming to highlight future directions, as well as chances to transfer existing knowledge from compiled language ecosystems. To that end, we work out key aspects in current research, systematize identified challenges for software reproducibility, and map them between the ecosystems.
Ultimately, the three authors find that the literature is sparse , focusing on few individual problems and ecosystems, and therefore identify space for more critical research.

Distribution work In Debian this month:
Hans-Christoph Steiner of the F-Droid catalogue of open source applications for the Android platform published a blog post on Making reproducible builds visible. Noting that Reproducible builds are essential in order to have trustworthy software , Hans also mentions that F-Droid has been delivering reproducible builds since 2015 . However:
There is now a Reproducibility Status link for each app on f-droid.org, listed on every app s page. Our verification server shows or based on its build results, where means our rebuilder reproduced the same APK file and means it did not. The IzzyOnDroid repository has developed a more elaborate system of badges which displays a for each rebuilder. Additionally, there is a sketch of a five-level graph to represent some aspects about which processes were run.
Hans compares the approach with projects such as Arch Linux and Debian that provide developer-facing tools to give feedback about reproducible builds, but do not display information about reproducible builds in the user-facing interfaces like the package management GUIs.
Arnout Engelen of the NixOS project has been working on reproducing the minimal installation ISO image. This month, Arnout has successfully reproduced the build of the minimal image for the 25.05 release without relying on the binary cache. Work on also reproducing the graphical installer image is ongoing.
In openSUSE news, Bernhard M. Wiedemann posted another monthly update for their work there.
Lastly in Fedora news, Jelle van der Waa opened issues tracking reproducible issues in Haskell documentation, Qt6 recording the host kernel and R packages recording the current date. The R packages can be made reproducible with packaging changes in Fedora.

diffoscope & disorderfs diffoscope is our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues. This month, Chris Lamb made the following changes, including preparing and uploading versions 295, 296 and 297 to Debian:
  • Don t rely on zipdetails --walk argument being available, and only add that argument on newer versions after we test for that. [ ]
  • Review and merge support for NuGet packages from Omair Majid. [ ]
  • Update copyright years. [ ]
  • Merge support for an lzma comparator from Will Hollywood. [ ][ ]
Chris also merged an impressive changeset from Siva Mahadevan to make disorderfs more portable, especially on FreeBSD. disorderfs is our FUSE-based filesystem that deliberately introduces non-determinism into directory system calls in order to flush out reproducibility issues [ ]. This was then uploaded to Debian as version 0.6.0-1. Lastly, Vagrant Cascadian updated diffoscope in GNU Guix to version 296 [ ][ ] and 297 [ ][ ], and disorderfs to version 0.6.0 [ ][ ].

Website updates Once again, there were a number of improvements made to our website this month including:

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework running primarily at tests.reproducible-builds.org in order to check packages and other artifacts for reproducibility. However, Holger Levsen posted to our mailing list this month in order to bring a wider awareness to funding issues faced by the Oregon State University (OSU) Open Source Lab (OSL). As mentioned on OSL s public post, recent changes in university funding makes our current funding model no longer sustainable [and that] unless we secure $250,000 in committed funds, the OSL will shut down later this year . As Holger notes in his post to our mailing list, the Reproducible Builds project relies on hardware nodes hosted there. Nevertheless, Lance Albertson of OSL posted an update to the funding situation later in the month with broadly positive news.
Separate to this, there were various changes to the Jenkins setup this month, which is used as the backend driver of for both tests.reproducible-builds.org and reproduce.debian.net, including:
  • Migrating the central jenkins.debian.net server AMD Opteron to Intel Haswell CPUs. Thanks to IONOS for hosting this server since 2012.
  • After testing it for almost ten years, the i386 architecture has been dropped from tests.reproducible-builds.org. This is because that, with the upcoming release of Debian trixie, i386 is no longer supported as a regular architecture there will be no official kernel and no Debian installer for i386 systems. As a result, a large number of nodes hosted by Infomaniak have been retooled from i386 to amd64.
  • Another node, ionos17-amd64.debian.net, which is used for verifying packages for all.reproduce.debian.net (hosted by IONOS) has had its memory increased from 40 to 64GB, and the number of cores doubled to 32 as well. In addition, two nodes generously hosted by OSUOSL have had their memory doubled to 16GB.
  • Lastly, we have been granted access to more riscv64 architecture boards, so now we have seven such nodes, all with 16GB memory and 4 cores that are verifying packages for riscv64.reproduce.debian.net. Many thanks to PLCT Lab, ISCAS for providing those.

Outside of this, a number of smaller changes were also made by Holger Levsen:
  • reproduce.debian.net-related:
    • Only use two workers for the ppc64el architecture due to RAM size. [ ]
    • Monitor nginx_request and nginx_status with the Munin monitoring system. [ ][ ]
    • Detect various variants of network and memory errors. [ ][ ][ ][ ]
    • Add a prominent link to reproducible-builds.org. [ ]
    • Add a rebuilderd-cache-cleanup.service and run it daily via timer. [ ][ ][ ][ ][ ]
    • Be more verbose what sources are being downloaded. [ ]
    • Correctly deal with packages with an epoch in their version [ ] and deal with binNMUs versions with an epoch as well [ ][ ].
    • Document how to reschedule all other errors on all archs. [ ]
    • Misc documentation improvements. [ ][ ][ ][ ]
    • Include the $HOSTNAME variable in the rebuilderd logfiles. [ ]
    • Install the equivs package on all worker nodes. [ ][ ]
  • Jenkins nodes:
    • Permit the sudo tool to fix up permission issues. [ ][ ]
    • Document how to manage diskspace with OpenStack. [ ]
    • Ignore a number of spurious monitoring errors on riscv64, FreeBSD, etc.. [ ][ ][ ][ ]
    • Install ntpsec-ntpdate (instead of ntpdate) as the former is available on Debian trixie and bookworm. [ ][ ]
    • Use the same SSH ControlPath for all nodes. [ ]
    • Make sure the munin user uses the same SSH config as the jenkins user. [ ]
  • tests.reproducible-builds.org-related:
    • Disable testing of the i386 architecture. [ ][ ][ ][ ][ ]
    • Document the current disk usage. [ ][ ]
    • Address some image placement now that we only test three architectures. [ ]
    • Keep track of build performance. [ ]
  • Misc:
    • Fix a (harmless) typo in the multiarch_versionskew script. [ ]
In addition, Jochen Sprickerhof made a series of changes related to reproduce.debian.net:
  • Add out of memory detection to the statistics page. [ ]
  • Reverse the sorting order on the statistics page. [ ][ ][ ][ ]
  • Improve the spacing between statistics groups. [ ]
  • Update a (hard-coded) line number in error message detection pertaining to a debrebuild line number. [ ]
  • Support Debian unstable in the rebuilder-debian.sh script. [ ] ]
  • Rely on rebuildctl to sync only arch-specific packages. [ ][ ]

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

Finally, 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:

Dirk Eddelbuettel: #49: The Two Cultures of Deploying Statistical Software

Welcome to post 49 in the R4 series. The Two Cultures is a term first used by C.P. Snow in a 1959 speech and monograph focused on the split between humanities and the sciences. Decades later, the term was (quite famously) re-used by Leo Breiman in a (somewhat prophetic) 2001 article about the split between data models and algorithmic models . In this note, we argue that statistical computing practice and deployment can also be described via this Two Cultures moniker. Referring to the term linking these foundational pieces is of course headline bait. Yet when preparing for the discussion of r2u in the invited talk in Mons (video, slides), it occurred to me that there is in fact a wide gulf between two alternative approaches of using R and, specifically, deploying packages. On the one hand we have the approach described by my friend Jeff as you go to the Apple store, buy the nicest machine you can afford, install what you need and then never ever touch it . A computer / workstation / laptop is seen as an immutable object where every attempt at change may lead to breakage, instability, and general chaos and is hence best avoided. If you know Jeff, you know he exaggerates. Maybe only slightly though. Similarly, an entire sub-culture of users striving for reproducibility (and sometimes also replicability ) does the same. This is for example evidenced by the popularity of package renv by Rcpp collaborator and pal Kevin. The expressed hope is that by nailing down a (sub)set of packages, outcomes are constrained to be unchanged. Hope springs eternal, clearly. (Personally, if need be, I do the same with Docker containers and their respective Dockerfile.) On the other hand, rolling is fundamentally different approach. One (well known) example is Google building everything at @HEAD . The entire (ginormous) code base is considered as a mono-repo which at any point in time is expected to be buildable as is. All changes made are pre-tested to be free of side effects to other parts. This sounds hard, and likely is more involved than an alternative of a whatever works approach of independent changes and just hoping for the best. Another example is a rolling (Linux) distribution as for example Debian. Changes are first committed to a staging place (Debian calls this the unstable distribution) and, if no side effects are seen, propagated after a fixed number of days to the rolling distribution (called testing ). With this mechanism, testing should always be installable too. And based on the rolling distribution, at certain times (for Debian roughly every two years) a release is made from testing into stable (following more elaborate testing). The released stable version is then immutable (apart from fixes for seriously grave bugs and of course security updates). So this provides the connection between frequent and rolling updates, and produces immutable fixed set: a release. This Debian approach has been influential for any other projects including CRAN as can be seen in aspects of its system providing a rolling set of curated packages. Instead of a staging area for all packages, extensive tests are made for candidate packages before adding an update. This aims to ensure quality and consistence and has worked remarkably well. We argue that it has clearly contributed to the success and renown of CRAN. Now, when accessing CRAN from R, we fundamentally have two accessor functions. But seemingly only one is widely known and used. In what we may call the Jeff model , everybody is happy to deploy install.packages() for initial installations. That sentiment is clearly expressed by this bsky post:
One of my #rstats coding rituals is that every time I load a @vincentab.bsky.social package I go check for a new version because invariably it s been updated with 18 new major features
And that is why we have two cultures. Because some of us, yours truly included, also use update.packages() at recurring (frequent !!) intervals: daily or near-daily for me. The goodness and, dare I say, gift of packages is not limited to those by my pal Vincent. CRAN updates all the time, and updates are (generally) full of (usually excellent) changes, fixes, or new features. So update frequently! Doing (many but small) updates (frequently) is less invasive than (large, infrequent) waterfall -style changes! But the fear of change, or disruption, is clearly pervasive. One can only speculate why. Is the experience of updating so painful on other operating systems? Is it maybe a lack of exposure / tutorials on best practices? These Two Cultures coexist. When I delivered the talk in Mons, I briefly asked for a show of hands among all the R users in the audience to see who in fact does use update.packages() regularly. And maybe a handful of hands went up: surprisingly few! Now back to the context of installing packages: Clearly only installing has its uses. For continuous integration checks we generally install into ephemeral temporary setups. Some debugging work may be with one-off container or virtual machine setups. But all other uses may well be under maintained setups. So consider calling update.packages() once in while. Or even weekly or daily. The rolling feature of CRAN is a real benefit, and it is there for the taking and enrichment of your statistical computing experience. So to sum up, the real power is to use For both tasks, relying on binary installations accelerates and eases the process. And where available, using binary installation with system-dependency support as r2u does makes it easier still, following the r2u slogan of Fast. Easy. Reliable. Pick All Three. Give it a try!

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can now sponsor me at GitHub.

5 June 2025

Matthew Garrett: How Twitter could (somewhat) fix their encrypted DMs

As I wrote in my last post, Twitter's new encrypted DM infrastructure is pretty awful. But the amount of work required to make it somewhat better isn't large.

When Juicebox is used with HSMs, it supports encrypting the communication between the client and the backend. This is handled by generating a unique keypair for each HSM. The public key is provided to the client, while the private key remains within the HSM. Even if you can see the traffic sent to the HSM, it's encrypted using the Noise protocol and so the user's encrypted secret data can't be retrieved.

But this is only useful if you know that the public key corresponds to a private key in the HSM! Right now there's no way to know this, but there's worse - the client doesn't have the public key built into it, it's supplied as a response to an API request made to Twitter's servers. Even if the current keys are associated with the HSMs, Twitter could swap them out with ones that aren't, terminate the encrypted connection at their endpoint, and then fake your query to the HSM and get the encrypted data that way. Worse, this could be done for specific targeted users, without any indication to the user that this has happened, making it almost impossible to detect in general.

This is at least partially fixable. Twitter could prove to a third party that their Juicebox keys were generated in an HSM, and the key material could be moved into clients. This makes attacking individual users more difficult (the backdoor code would need to be shipped in the public client), but can't easily help with the website version[1] even if a framework exists to analyse the clients and verify that the correct public keys are in use.

It's still worse than Signal. Use Signal.

[1] Since they could still just serve backdoored Javascript to specific users. This is, unfortunately, kind of an inherent problem when it comes to web-based clients - we don't have good frameworks to detect whether the site itself is malicious.

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4 June 2025

Gunnar Wolf: The subjective value of privacy Assessing individuals' calculus of costs and benefits in the context of state surveillance

This post is an unpublished review for The subjective value of privacy Assessing individuals' calculus of costs and benefits in the context of state surveillance
Internet users, software developers, academics, entrepreneurs basically everybody is now aware of the importance of considering privacy as a core part of our online experience. User demand, and various national or regional laws, have made privacy a continuously present subject. And privacy is such an all-encompassing, complex topic, the angles from which it can be studied seems never to finish; I recommend computer networking-oriented newcomers to the topic to refer to Brian Kernighan s excellent work [1]. However, how do regular people like ourselves, in our many capacities feel about privacy? Lukas Antoine presents a series of experiments aiming at better understanding how people throughout the world understands privacy, and when is privacy held as more or less important than security in different aspects, Particularly, privacy is often portrayed as a value set at tension against surveillance, and particularly state surveillance, in the name of security: conventional wisdom presents the idea of privacy calculus. This is, it is often assumed that individuals continuously evaluate the costs and benefits of divulging their personal data, sharing data when they expect a positive net outcome, and denying it otherwise. This framework has been accepted for decades, and the author wishes to challenge it. This book is clearly his doctoral thesis on political sciences, and its contents are as thorough as expected in this kind of product. The author presents three empirical studies based on cross-survey analysis. The first experiment explores the security justifications for surveillance and how they influence their support. The second one searches whether the stance on surveillance can be made dependent on personal convenience or financial cost. The third study explores whether privacy attitude is context-dependant or can be seen as a stable personality trait. The studies aim to address the shortcomings of published literature in the field, mainly, (a) the lack of comprehensive research on state surveillance, needed or better understanding privacy appreciation, (b) while several studies have tackled the subjective measure of privacy, there is a lack of cross-national studies to explain wide-ranging phenomena, (c) most studies in this regard are based on population-based surveys, which cannot establish causal relationships, (d) a seemingly blind acceptance of the privacy calculus mentioned above, with no strong evidence that it accurately measures people s motivations for disclosing or withholding their data. The specific take, including the framing of the tension between privacy and surveillance has long been studied, as can be seen in Steven Nock s 1993 book [2], but as Sannon s article in 2022 shows [3], social and technological realities require our undertanding to be continuously kept up to date. The book is full with theoretical references and does a very good job of explaining the path followed by the author. It is, though, a heavy read, and, for people not coming from the social sciences tradition, leads to the occasional feeling of being lost. The conceptual and theoretical frameworks and presented studies are thorough and clear. The author is honest in explaining when the data points at some of his hypotheses being disproven, while others are confirmed. The aim of the book is for people digging deep into this topic. Personally, I have authored several works on different aspects of privacy (such as a book [4] and a magazine number [5]), but this book did get me thinking on many issues I had not previously considered. Looking for comparable works, I find Friedewald et al. s 2017 book [6] chapter organization to follow a similar thought line. My only complaint would be that, for the publication as part of its highly prestigious publisher, little attention has been paid to editorial aspects: sub-subsection depth is often excessive and unclear. Also, when publishing monographs based on doctoral works, it is customary to no longer refer to the work as a thesis and to soften some of the formal requirements such a work often has, with the aim of producing a more gentle and readable book; this book seems just like the mass-production of an (otherwise very interesting and well made) thesis work. References:

Gunnar Wolf: Beyond data poisoning in federated learning

This post is an unpublished review for Beyond data poisoning in federated learning
The current boom of artificial intelligence (AI) is based upon neural networks (NNs). In order for these to be useful, the network has to undergo a machine learning (ML) process: work over a series of inputs, and adjust the inner weights of the connections between neurons so that each of the data samples the network was trained on produces the right set of labels for each item. Federated learning (FL) appeared as a reaction given the data centralization power that traditional ML provides: instead of centrally controlling the whole training data, various different actors analyze disjoint subsets of data, and provide only the results of this analysis, thus increasing privacy while analyzing a large dataset. Finally, given multiple actors are involved in FL, how hard is it for a hostile actor to provide data that will confuse the NN, instead of helping it reach better performance? This kind of attack is termed a poisoning attack, and is the main focus of this paper. The authors set out to research how effective can a hyperdimensional data poisoning attack (HDPA) be to confuse a NN and cause it to misclassify both the items trained on and yet unseen items. Data used for NN training is usually represented as a large set of orthogonal vectors, each describing a different aspect of the item, allowing for very simple vector arithmetic operations. Thus, NN training is termed as high-dimensional or hyperdimensional. The attack method described by the authors employs cosine similarity, that is, in order to preserve similarity, a target hypervector is reflected over a given dimension, yielding a cosine-similar result that will trick ML models, even if using byzantine-robust defenses. The paper is clear, though not an easy read. It explains in detail the mathematical operations, following several related although different threat models. The authors present the results of the experimental evaluation of their proposed model, comparing it to several other well-known adversarial attacks for visual recognition tasks, over pre-labeled datasets frequently used as training data, such as MNIST, Fashion-MNIST and CIFAR-10. They show that their method is not only more effective as an attack, but falls within the same time range as other surveyed attacks. Adversarial attacks are, all in all, an important way to advance any field of knowledge; by publishing this attack, the authors will surely spark other works to detect and prevent this kind of alteration. It is important for AI implementers to understand the nature of this field and be aware of the risks that this work, as well as others cited in it, highlight: ML will train a computer system to recognize a dataset, warts and all; efficient as AI is, if noise is allowed into the training data (particularly adversarially generated noise), the trained model might present impaired performance.

1 June 2025

Ben Hutchings: FOSS activity in May 2025

31 May 2025

Russell Coker: Links May 2025

Christopher Biggs gave an informative Evrything Open lecture about voice recognition [1]. We need this on Debian phones. Guido wrote an informative blog post about booting a custom Android kernel on a Pixel 3a [2]. Good work in writing this up, but a pity that Google made the process so difficult. Interesting to read about an expert being a victim of a phishing attack [3]. It can happen to anyone, everyone has moments when they aren t concentrating. Interesting advice on how to leak to a journalist [4]. Brian Krebs wrote an informative article about the ways that Trump is deliberately reducing the cyber security of the US government [5]. Brian Krebs wrote an interesting article about the main smishng groups from China [6]. Louis Rossmann (who is known for high quality YouTube videos about computer repair) made an informative video about a scammy Australian company run by a child sex offender [7]. The Helmover was one of the wildest engineering projects of WW2, an over the horizon guided torpedo that could one-shot a battleship [8]. Interesting blog post about DDoSecrets and the utter failure of the company Telemessages which was used by the US government [9]. Jonathan McDowell wrote an interesting blog post about developing a free software competitor to Alexa etc, the listening hardware costs $13US per node [10]. Noema Magazine published an insightful article about Rewilding the Internet, it has some great ideas [11].

Antoine Beaupr : Traffic meter per ASN without logs

Have you ever found yourself in the situation where you had no or anonymized logs and still wanted to figure out where your traffic was coming from? Or you have multiple upstreams and are looking to see if you can save fees by getting into peering agreements with some other party? Or your site is getting heavy load but you can't pinpoint it on a single IP and you suspect some amoral corporation is training their degenerate AI on your content with a bot army? (You might be getting onto something there.) If that rings a bell, read on.

TL;DR: ... or just skip the cruft and install asncounter:
pip install asncounter
Also available in Debian 14 or later, or possibly in Debian 13 backports (soon to be released) if people are interested:
apt install asncounter
Then count whoever is hitting your network with:
awk ' print $2 ' /var/log/apache2/*access*.log   asncounter
or:
tail -F /var/log/apache2/*access*.log   awk ' print $2 '   asncounter
or:
tcpdump -q -n   asncounter --input-format=tcpdump --repl
or:
tcpdump -q -i eth0 -n -Q in "tcp and tcp[tcpflags] & tcp-syn != 0 and (port 80 or port 443)"   asncounter --input-format=tcpdump --repl
Read on for why this matters, and why I wrote yet another weird tool (almost) from scratch.

Background and manual work This is a tool I've been dreaming of for a long, long time. Back in 2006, at Koumbit a colleague had setup TAS ("Traffic Accounting System", " " in Russian, apparently), a collection of Perl script that would do per-IP accounting. It was pretty cool: it would count bytes per IP addresses and, from that, you could do analysis. But the project died, and it was kind of bespoke. Fast forward twenty years, and I find myself fighting off bots at the Tor Project (the irony...), with our GitLab suffering pretty bad slowdowns (see issue tpo/tpa/team#41677 for the latest public issue, the juicier one is confidential, unfortunately). (We did have some issues caused by overloads in CI, as we host, after all, a fork of Firefox, which is a massive repository, but the applications team did sustained, awesome work to fix issues on that side, again and again (see tpo/applications/tor-browser#43121 for the latest, and tpo/applications/tor-browser#43121 for some pretty impressive correlation work, I work with really skilled people). But those issues, I believe were fixed.) So I had the feeling it was our turn to get hammered by the AI bots. But how do we tell? I could tell something was hammering at the costly /commit/ and (especially costly) /blame/ endpoint. So at first, I pulled out the trusted awk, sort uniq -c sort -n tail pipeline I am sure others have worked out before:
awk ' print $1 ' /var/log/nginx/*.log   sort   uniq -c   sort -n   tail -10
For people new to this, that pulls the first field out of web server log files, sort the list, counts the number of unique entries, and sorts that so that the most common entries (or IPs) show up first, then show the top 10. That, other words, answers the question of "which IP address visits this web server the most?" Based on this, I found a couple of IP addresses that looked like Alibaba. I had already addressed an abuse complaint to them (tpo/tpa/team#42152) but never got a response, so I just blocked their entire network blocks, rather violently:
for cidr in 47.240.0.0/14 47.246.0.0/16 47.244.0.0/15 47.235.0.0/16 47.236.0.0/14; do 
  iptables-legacy -I INPUT -s $cidr -j REJECT
done
That made Ali Baba and his forty thieves (specifically their AL-3 network go away, but our load was still high, and I was still seeing various IPs crawling the costly endpoints. And this time, it was hard to tell who they were: you'll notice all the Alibaba IPs are inside the same 47.0.0.0/8 prefix. Although it's not a /8 itself, it's all inside the same prefix, so it's visually easy to pick it apart, especially for a brain like mine who's stared too long at logs flowing by too fast for their own mental health. What I had then was different, and I was tired of doing the stupid thing I had been doing for decades at this point. I had recently stumbled upon pyasn recently (in January, according to my notes) and somehow found it again, and thought "I bet I could write a quick script that loops over IPs and counts IPs per ASN". (Obviously, there are lots of other tools out there for that kind of monitoring. Argos, for example, presumably does this, but it's a kind of a huge stack. You can also get into netflows, but there's serious privacy implications with those. There are also lots of per-IP counters like promacct, but that doesn't scale. Or maybe someone already had solved this problem and I just wasted a week of my life, who knows. Someone will let me know, I hope, either way.)

ASNs and networks A quick aside, for people not familiar with how the internet works. People that know about ASNs, BGP announcements and so on can skip. The internet is the network of networks. It's made of multiple networks that talk to each other. The way this works is there is a Border Gateway Protocol (BGP), a relatively simple TCP-based protocol, that the edge routers of those networks used to announce each other what network they manage. Each of those network is called an Autonomous System (AS) and has an AS number (ASN) to uniquely identify it. Just like IP addresses, ASNs are allocated by IANA and local registries, they're pretty cheap and useful if you like running your own routers, get one. When you have an ASN, you'll use it to, say, announce to your BGP neighbors "I have 198.51.100.0/24" over here and the others might say "okay, and I have 216.90.108.31/19 over here, and I know of this other ASN over there that has 192.0.2.1/24 too! And gradually, those announcements flood the entire network, and you end up with each BGP having a routing table of the global internet, with a map of which network block, or "prefix" is announced by which ASN. It's how the internet works, and it's a useful thing to know, because it's what, ultimately, makes an organisation responsible for an IP address. There are "looking glass" tools like the one provided by routeviews.org which allow you to effectively run "trace routes" (but not the same as traceroute, which actively sends probes from your location), type an IP address in that form to fiddle with it. You will end up with an "AS path", the way to get from the looking glass to the announced network. But I digress, and that's kind of out of scope. Point is, internet is made of networks, networks are autonomous systems (AS) and they have numbers (ASNs), and they announced IP prefixes (or "network blocks") that ultimately tells you who is responsible for traffic on the internet.

Introducing asncounter So my goal was to get from "lots of IP addresses" to "list of ASNs", possibly also the list of prefixes (because why not). Turns out pyasn makes that really easy. I managed to build a prototype in probably less than an hour, just look at the first version, it's 44 lines (sloccount) of Python, and it works, provided you have already downloaded the required datafiles from routeviews.org. (Obviously, the latest version is longer at close to 1000 lines, but it downloads the data files automatically, and has many more features). The way the first prototype (and later versions too, mostly) worked is that you feed it a list of IP addresses on standard input, it looks up the ASN and prefix associated with the IP, and increments a counter for those, then print the result. That showed me something like this:
root@gitlab-02:~/anarcat-scripts# tcpdump -q -i eth0 -n -Q in "(udp or tcp)"   ./asncounter.py --tcpdump                                                                                                                                                                          
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode                                                                
listening on eth0, link-type EN10MB (Ethernet), snapshot length 262144 bytes                                                             
INFO: collecting IPs from stdin, using datfile ipasn_20250523.1600.dat.gz                                                                
INFO: loading datfile /root/.cache/pyasn/ipasn_20250523.1600.dat.gz...                                                                   
INFO: loading /root/.cache/pyasn/asnames.json                       
ASN     count   AS               
136907  7811    HWCLOUDS-AS-AP HUAWEI CLOUDS, HK                                                                                         
[----]  359     [REDACTED]
[----]  313     [REDACTED]
8075    254     MICROSOFT-CORP-MSN-AS-BLOCK, US
[---]   164     [REDACTED]
[----]  136     [REDACTED]
24940   114     HETZNER-AS, DE  
[----]  98      [REDACTED]
14618   82      AMAZON-AES, US                                                                                                           
[----]  79      [REDACTED]
prefix  count                                         
166.108.192.0/20        1294                                                                                                             
188.239.32.0/20 1056                                          
166.108.224.0/20        970                    
111.119.192.0/20        951              
124.243.128.0/18        667                                         
94.74.80.0/20   651                                                 
111.119.224.0/20        622                                         
111.119.240.0/20        566           
111.119.208.0/20        538                                         
[REDACTED]  313           
Even without ratios and a total count (which will come later), it was quite clear that Huawei was doing something big on the server. At that point, it was responsible for a quarter to half of the traffic on our GitLab server or about 5-10 queries per second. But just looking at the logs, or per IP hit counts, it was really hard to tell. That traffic is really well distributed. If you look more closely at the output above, you'll notice I redacted a couple of entries except major providers, for privacy reasons. But you'll also notice almost nothing is redacted in the prefix list, why? Because all of those networks are Huawei! Their announcements are kind of bonkers: they have hundreds of such prefixes. Now, clever people in the know will say "of course they do, it's an hyperscaler; just ASN14618 (AMAZON-AES) there is way more announcements, they have 1416 prefixes!" Yes, of course, but they are not generating half of my traffic (at least, not yet). But even then: this also applies to Amazon! This way of counting traffic is way more useful for large scale operations like this, because you group by organisation instead of by server or individual endpoint. And, ultimately, this is why asncounter matters: it allows you to group your traffic by organisation, the place you can actually negotiate with. Now, of course, that assumes those are entities you can talk with. I have written to both Alibaba and Huawei, and have yet to receive a response. I assume I never will. In their defence, I wrote in English, perhaps I should have made the effort of translating my message in Chinese, but then again English is the Lingua Franca of the Internet, and I doubt that's actually the issue.

The Huawei and Facebook blocks Another aside, because this is my blog and I am not looking for a Pullitzer here. So I blocked Huawei from our GitLab server (and before you tear your shirt open: only our GitLab server, everything else is still accessible to them, including our email server to respond to my complaint). I did so 24h after emailing them, and after examining their user agent (UA) headers. Boy that was fun. In a sample of 268 requests I analyzed, they churned out 246 different UAs. At first glance, they looked legit, like:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36
Safari on a Mac, so far so good. But when you start digging, you notice some strange things, like here's Safari running on Linux:
Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/534.3 (KHTML, like Gecko) Chrome/6.0.457.0 Safari/534.3
Was Safari ported to Linux? I guess that's.. possible? But here is Safari running on a 15 year old Ubuntu release (10.10):
Mozilla/5.0 (X11; Linux i686) AppleWebKit/534.24 (KHTML, like Gecko) Ubuntu/10.10 Chromium/12.0.702.0 Chrome/12.0.702.0 Safari/534.24
Speaking of old, here's Safari again, but this time running on Windows NT 5.1, AKA Windows XP, released 2001, EOL since 2019:
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-CA) AppleWebKit/534.13 (KHTML like Gecko) Chrome/9.0.597.98 Safari/534.13
Really? Here's Firefox 3.6, released 14 years ago, there were quite a lot of those:
Mozilla/5.0 (Windows; U; Windows NT 6.1; lt; rv:1.9.2) Gecko/20100115 Firefox/3.6
I remember running those old Firefox releases, those were the days. But to me, those look like entirely fake UAs, deliberately rotated to make it look like legitimate traffic. In comparison, Facebook seemed a bit more legit, in the sense that they don't fake it. most hits are from:
meta-externalagent/1.1 (+https://developers.facebook.com/docs/sharing/webmasters/crawler)
which, according their documentation:
crawls the web for use cases such as training AI models or improving products by indexing content directly
From what I could tell, it was even respecting our rather liberal robots.txt rules, in that it wasn't crawling the sprawling /blame/ or /commit/ endpoints, explicitly forbidden by robots.txt. So I've blocked the Facebook bot in robots.txt and, amazingly, it just went away. Good job Facebook, as much as I think you've given the empire to neo-nazis, cause depression and genocide, you know how to run a crawler, thanks. Huawei was blocked at the web server level, with a friendly 429 status code telling people to contact us (over email) if they need help. And they don't care: they're still hammering the server, from what I can tell, but then again, I didn't block the entire ASN just yet, just the blocks I found crawling the server over a couple hours.

A full asncounter run So what does a day in asncounter look like? Well, you start with a problem, say you're getting too much traffic and want to see where it's from. First you need to sample it. Typically, you'd do that with tcpdump or tailing a log file:
tail -F /var/log/apache2/*access*.log   awk ' print $2 '   asncounter
If you have lots of traffic or care about your users' privacy, you're not going to log IP addresses, so tcpdump is likely a good option instead:
tcpdump -q -n   asncounter --input-format=tcpdump --repl
If you really get a lot of traffic, you might want to get a subset of that to avoid overwhelming asncounter, it's not fast enough to do multiple gigabit/second, I bet, so here's only incoming SYN IPv4 packets:
tcpdump -q -n -Q in "tcp and tcp[tcpflags] & tcp-syn != 0 and (port 80 or port 443)"   asncounter --input-format=tcpdump --repl
In any case, at this point you're staring at a process, just sitting there. If you passed the --repl or --manhole arguments, you're lucky: you have a Python shell inside the program. Otherwise, send SIGHUP to the thing to have it dump the nice tables out:
pkill -HUP asncounter
Here's an example run:
> awk ' print $2 ' /var/log/apache2/*access*.log   asncounter
INFO: using datfile ipasn_20250527.1600.dat.gz
INFO: collecting addresses from <stdin>
INFO: loading datfile /home/anarcat/.cache/pyasn/ipasn_20250527.1600.dat.gz...
INFO: finished reading data
INFO: loading /home/anarcat/.cache/pyasn/asnames.json
count   percent ASN AS
12779   69.33   66496   SAMPLE, CA
3361    18.23   None    None
366 1.99    66497   EXAMPLE, FR
337 1.83    16276   OVH, FR
321 1.74    8075    MICROSOFT-CORP-MSN-AS-BLOCK, US
309 1.68    14061   DIGITALOCEAN-ASN, US
128 0.69    16509   AMAZON-02, US
77  0.42    48090   DMZHOST, GB
56  0.3 136907  HWCLOUDS-AS-AP HUAWEI CLOUDS, HK
53  0.29    17621   CNCGROUP-SH China Unicom Shanghai network, CN
total: 18433
count   percent prefix  ASN AS
12779   69.33   192.0.2.0/24    66496   SAMPLE, CA
3361    18.23   None        
298 1.62    178.128.208.0/20    14061   DIGITALOCEAN-ASN, US
289 1.57    51.222.0.0/16   16276   OVH, FR
272 1.48    2001:DB8::/48   66497   EXAMPLE, FR
235 1.27    172.160.0.0/11  8075    MICROSOFT-CORP-MSN-AS-BLOCK, US
94  0.51    2001:DB8:1::/48 66497   EXAMPLE, FR
72  0.39    47.128.0.0/14   16509   AMAZON-02, US
69  0.37    93.123.109.0/24 48090   DMZHOST, GB
53  0.29    27.115.124.0/24 17621   CNCGROUP-SH China Unicom Shanghai network, CN
Those numbers are actually from my home network, not GitLab. Over there, the battle still rages on, but at least the vampire bots are banging their heads against the solid Nginx wall instead of eating the fragile heart of GitLab. We had a significant improvement in latency thanks to the Facebook and Huawei blocks... Here are the "workhorse request duration stats" for various time ranges, 20h after the block:
range mean max stdev
20h 449ms 958ms 39ms
7d 1.78s 5m 14.9s
30d 2.08s 3.86m 8.86s
6m 901ms 27.3s 2.43s
We went from two seconds mean to 500ms! And look at that standard deviation! 39ms! It was ten seconds before! I doubt we'll keep it that way very long but for now, it feels like I won a battle, and I didn't even have to setup anubis or go-away, although I suspect that will unfortunately come. Note that asncounter also supports exporting Prometheus metrics, but you should be careful with this, as it can lead to cardinal explosion, especially if you track by prefix (which can be disabled with --no-prefixes . Folks interested in more details should read the fine manual for more examples, usage, and discussion. It shows, among other things, how to effectively block lots of networks from Nginx, aggregate multiple prefixes, block entire ASNs, and more! So there you have it: I now have the tool I wish I had 20 years ago. Hopefully it will stay useful for another 20 years, although I'm not sure we'll have still have internet in 20 years. I welcome constructive feedback, "oh no you rewrote X", Grafana dashboards, bug reports, pull requests, and "hell yeah" comments. Hacker News, let it rip, I know you can give me another juicy quote for my blog. This work was done as part of my paid work for the Tor Project, currently in a fundraising drive, give us money if you like what you read.

30 May 2025

Russell Coker: Service Setup Difficulties

Marco wrote a blog post opposing hyperscale systems which included We want to use an hyperscaler cloud because our developers do not want to operate a scalable and redundant database just means that you need to hire competent developers and/or system administrators. [1]. I previously wrote a blog post Why Clusters Usually Don t Work [2] and I believe that all the points there are valid today and possibly exacerbated by clusters getting less direct use as clustering is increasingly being done by hyperscale providers. Take a basic need, a MySQL or PostgreSQL database for example. You want it to run and basically do the job and to have good recovery options. You could set it up locally, run backups, test the backups, have a recovery plan for failures, maybe have a hot-spare server if it s really important, have tests for backups and hot-spare server, etc. Then you could have documentation for this so if the person who set it up isn t available when there s a problem they will be able to find out what to do. But the hyperscale option is to just select a database in your provider and have all this just work. If the person who set it up isn t available for recovery in the event of failure the company can just put out a job advert for person with experience on cloud company X and have them just immediately go to work on it. I don t like hyperscale providers as they are all monopolistic companies that do anti-competitive actions. Google should be broken up, Android development and the Play Store should be separated from Gmail etc which should be separated from search and adverts, and all of them should be separated from the GCP cloud service. Amazon should be broken up, running the Amazon store should be separated from selling items on the store, which should be separated from running a video on demand platform, and all of them should be separated from the AWS cloud. Microsoft should be broken up, OS development should be separated from application development all of that should be separated from cloud services (Teams and Office 365), and everything else should be separate from the Azure cloud system. But the cloud providers offer real benefits at small scale. Running a MySQL or PostgreSQL database for local services is easy, it s a simple apt command to install it and then it basically works. Doing backup and recovery isn t so easy. One could say just hire competent people but if you do hire competent people do you want them running MySQL databases etc or have them just click on the create mysql database option on a cloud control panel and then move on to more important things? The FreedomBox project is a great project for installing and managing home/personal services [3]. But it s not about running things like database servers, it s for a high level running mail servers and other things for the user not for the developer. The Debian packaging of Open Stack looks interesting [4], it s a complete setup for running your own hyper scale cloud service. For medium and large organisations running Open Stack could be a good approach. But for small organisations it s cheaper and easier to just use a cloud service to run things. The issue of when to run things in-house and when to put them in the cloud is very complex. I think that if the organisation is going to spend less money on cloud services than on the salary of one sysadmin then it s probably best to have things in the cloud. When cloud costs start to exceed the salary of one person who manages systems then having them spend the extra time and effort to run things locally starts making more sense. There is also an opportunity cost in having a good sysadmin work on the backups for all the different systems instead of letting the cloud provider just do it. Another possibility of course is to run things in-house on low end hardware and just deal with the occasional downtime to save money. Knowingly choosing less reliability to save money can be quite reasonable as long as you have considered the options and all the responsible people are involved in the discussion. The one situation that I strongly oppose is having hyper scale services setup by people who don t understand them. Running a database server on a cloud service because you don t want to spend the time managing it is a reasonable choice in many situations. Running a database server on a cloud service because you don t understand how to setup a database server is never a good choice. While the cloud services are quite resilient there are still ways of breaking the overall system if you don t understand it. Also while it is quite possible for someone to know how to develop for databases including avoiding SQL injection etc but be unable to setup a database server that s probably not going to be common, probably if someone can t set it up (a generally easy task) then they can t do the hard tasks of making it secure.

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