This is Chris Webb’s home page. The best way to contact me is by email to chris@arachsys.com. You can also follow me as @dairychris on Twitter, or find me on Facebook.
A number of my free software projects are available on GitHub, BitBucket, Codeberg, GitLab and Sourcehut. You might be looking for:
containers — lightweight containers using Linux namespaces
This package is a minimalist implementation of containers for Linux, making secure containers as easy to create and use as a traditional chroot. It comprises three utilities, contain, inject and pseudo, which use the kernel support for user namespaces merged in Linux 3.8. See also ucontain, a simplified shell script reimplementation.
cts-tool — a command-line interface to the British cattle tracing system
The British Cattle Movement Service run a tracing database for farmers to record cattle births, deaths and movements. This command-line interface to their XML-over-HTTP API is an alternative to the clunky web frontend.
init — a BSD-style init, daemon, syslog and udev replacement
A lightweight init suite used in Arachsys Linux, this is a toolkit of
small utilities including a daemon wrapper supporting asynchronous
dependencies and listening sockets, a simple but flexible syslog
implementation, an elegant replacement for the increasingly bloated udev
daemon, and a template /etc/init written as a simple shell script.
libelf — freestanding libelf extracted from elfutils
This builds cleanly without autotools on both musl and glibc, using either clang or gcc. On musl systems it doesn’t need extra argp, fts or obstack libraries, just zlib for handling compressed ELF sections.
mailflow and mailwrap — improved plain text email in Apple Mail
I sometimes used to work on an Apple machine running macOS, and it was convenient to use the built-in IMAP mail client. It isn’t too bad for reading mail, but whilst it once emitted nice RFC2646 format=flowed message bodies, recent releases horribly mangle plain text with a quoted-printable transfer encoding.
MailFlow monkey-patches Apple Mail to emit format=flowed plain text messages, also fixing problems with displaying leading whitespace, and quoting/attribution in replies. MailWrap is an earlier plugin to add a manual line-wrapping and paragraph filling shortcuts in the message composer. Unfortunately, plugins like these are no longer possible on the most recent releases of Apple Mail, though the bugs and problems they worked around are still glaringly obvious.
microdns — authoritative name server based on Dan Bernstein’s tinydns
This is my fork of Dan’s public domain tinydns, reworked and updated for modern RFC compliance, efficient multiplexed TCP service and full IPv6 support. It is actively maintained but has diverged a bit from the classic codebase.
montage — resources for Yamaha Montage synthesisers
These include simple utilities, reverse-engineered file formats, undocumented sysex commands, instructions for obtaining a shell, and hardware notes.
neova — a tool to configure the Enhancia Neova ring controller
This command-line interface covers the same functions as the graphical Neova Dashboard application but is portable, scriptable and more convenient to use.
nobmc — hardware to reset and power-cycle servers using serial console breaks
These small boards were designed to allow remote management of Arachsys servers over an RS232 serial console, bypassing the integrated BMCs which are clunky, unreliable and horribly insecure.
openntpd — alternative multiplatform openntpd
This is an alternative multiplatform repackaging of OpenBSD’s openntpd, compatible with Linux glibc, Linux musl, FreeBSD, NetBSD and DragonFly, as well as the original OpenBSD. It is actively maintained, includes a number of fixes and quality-of-life improvements and isn’t obfuscated by autoconf, automake and libtool.
pocketcrypt — a lightweight legacy-free cryptographic library
Pocketcrypt is a tiny legacy-free cryptographic library providing duplex constructions using NIST LWC finalists Gimli and Xoodoo, together with standard X25519 for key exchange and Schnorr signatures. Eschewing interoperability with the standard museum of primitives and protocols, it offers concise, easily-understood and easy-to-audit code that avoids the ugly boilerplate and obfuscation of larger libraries.
skd — attach scripts to unix, IPv4 or IPv6 listening sockets
skd is my original socket daemon, written as an inetd replacement in the mid-1990s. It binds to a UDP, TCP or unix socket, waits for connections and runs a specified program to handle them. See also the daemon utility in my more recent init suite which can listen on TCP and unix sockets in a similar way and is a better choice for new applications.
ssh-x25519 — map ssh-ed25519 keys into x25519 keys
This trivial wrapper around standard Go crypto libraries converts OpenSSH ssh-ed25519 identities to x25519 keys for use in other contexts such as file encryption or key exchange, compatible with simple, easy-to-audit x25519 libraries like Pocketcrypt.
tinyacme — order certificates using ACME TLS-ALPN-01
These small stand-alone utilities automatically provision/renew TLS certificates from ACME-based providers such as Let’s Encrypt.
tinymbim — bring up a mobile internet connection using MBIM
Tinymbim is a command-line utility to control an MBIM-compatible mobile broadband modem on Linux using its cdc-wdm control device.
tinyquota — control filesystem quotas on Linux
These tools manipulate block and file quotas by user, group or project ID, taking advantage of the native quota support in ext4 and xfs.
tube — an authenticated bidirectional peer-to-peer pipe using Pocketcrypt
This is a worked example which generalises Magic Wormhole’s style of peer-to-peer file transfer into a bidirectional pipe. Peers authenticate with a short shared secret and a PAKE. Both rendezvous server and client are fully implemented but at present they are only documented in the design discussion in the git commit log. The client, server and cryptographic library span fewer than 1100 lines of C in total.
ucom — a cruft-free serial terminal
ucom is a serial terminal in the style of cu, minicom and GNU screen, but without legacy modem control, file transfer or a nested terminal emulation layer. In fewer than 150 lines of C, it provides a clean interactive session with a serial port, aiming for both correctness and efficiency.
ucontain — a simplified bash version of containers using unshare and pivot
This demonstrates how to use namespaces and ad hoc containers in scripts, wrapping unshare and nsenter from util-linux, newuidmap and newgidmap from shadow-utils, pivot and seal from Arachsys init. See also the original containers package.
webmidi — a series of self-contained Web MIDI tools
Each single-page application interacts with attached MIDI instruments using the Web MIDI API, runs entirely client-side and depends on no resources outside its static HTML file.
zf — a compressor-based spam filter
This abuses zstd dictionary compression to classify inbound email. The technique is straightforward and inexpensive but nonetheless achieves state-of-the-art filtering accuracy with realistic training sets of a few thousand messages per category. See also my earlier af filter which wrapped the OSBF-Lua module to achieve similar filtering performance.
Other bits and pieces including paragliding scripts, Yamaha synthesiser stuff and Arachsys Linux package trees can be found amongst my public repositories.
Please contact me by email with any comments, bug reports or proposed patches, rather than using GitHub web-based pull requests or issues.
Since late 1999, I’ve maintained Arachsys Linux, an opinionated ‘from scratch’ Linux distribution for my development machines and production servers, porting from 32-bit x86 to x86-64 and arm64 in the mid-2000s. More recently, I’ve also deployed it on arm32 routers and arm64 embedded projects.
Unusual features include musl libc, support for
both llvm and gcc toolchains, a simple shell-script /etc/init assisted by
my init tools, and a willingness to
clean up cruft at the expense of legacy compatibility. There is no /usr,
/sbin, /include or /share on an Arachsys Linux system, just /bin
and /lib. Shared and static libraries live in /lib/shared and
/lib/static respectively, with headers in /lib/include.
Consumer distributions invariably stuff /etc with hundreds of default
config files filled with comments that should be documentation, whereas an
Arachsys /etc only contains a handful of files deliberately written by
the user. Similarly, the distribution embraces the trend to tidy
user-specific configuration into ~/.config, patching programs to enforce
this where necessary. For example, bash, readline and ssh are configured
from ~/.config although none of these are likely to support this
upstream.
Software is packaged properly so pkg-config and friends are redundant.
Libraries are on the standard link path if they are available; header files
are on the standard include path if they are available. As a result, the
filesystem isn’t littered with .la and .pc droppings.
Build recipes now include upstream URLs so the pkg tool can check for new
releases across the entire tree. This eliminates the need to track updates
manually, which is time-consuming and error-prone with large numbers of
packages.
My limited time as a solo maintainer means there is little documentation
other than the package tree and
commit log, but the pkg
build tool is written in clear, easy-to-read bash and is maintained
in tree. I upload
periodic snapshots of the binary images needed to bootstrap a system on
the GitHub releases page.
I’m a beef farmer and calf rearer in North Shropshire. I tweet photographs, occasional rants about agricultural technology, and general updates on the cattle and my day-to-day farming exploits as @dairychris on Twitter.
My long-term public identity is the elliptic curve point represented in
OpenSSH format as ssh-ed25519
AAAAC3NzaC1lZDI1NTE5AAAAIMHPkQPn4+cxxP2Ax29Ozhkvu7Vp0KMlPAncD6fFmqCb and in
base64-encoded X25519 form as
cyUynIqlEg8JL96nxStP4LKfECrYomQXrAdC6jurVwE=.
I use the corresponding private key to sign releases and git tags, and to authenticate myself more generally.