“Elegance is not a dispensable luxury” — Edsger Wybe Dijkstra

Summer of Code 2015

Summer is now slowly fading away, and what a summer it has been here in Sweden! For someone who isn’t a fan of the summer heat it has been an awesome time for brain work, and in my case work on my open source projects! :-)

Due to my not really taking much vacation previous years I had saved up for ten weeks (10) this year! It was really worth it, and for the first time in many years I actually feel rested.

So what’s new? Well, this summer I’ve released a major upgrade to pimd, which received PIM-SSM and full IGMPv3 support! Inadyn has seen two releases, one feature release with support for Windows and improved support for custom DDNS providers, and one bugfix release (today). My own FTP/TFTP server uftpd has also got a bit of an overhaul to improve both concurrency and improved support for various popular clients (Firefox and wget) – I released v1.9 of uftpd as a birthday present to myself! ;-)

I’ve done some other minor work as well, on the “new” netcalc, IPv6 and IPv4 subnet calculator, as well as watchdogd and finit. The latter two have however not seen any releases yet, but both have major v2.0 releases with lots of very interesting features that are going to be revealed soon!

For watchdogd several big improvements to system monitoring (loadavg, file descriptors, RAM) as well as a very advanced process monitoring (instrumentation) API is being added. Finit however is the crown in making, it is being converted to support multiple instances of services and to be a fully event driven. I’m extremely excited about Finit!

Oh, and don’t worry … I did manage to get some actual real downtime on the beach as well! ;-)

HowTo: Using -lite With a GIT-based Application

Years ago while looking for a fast init replacement for work, I found Finit. Originally written by Claudio Matsuoka to act as a drop-in replacement for the Asus EeePC fastinit, “gaps filled with frog DNA …”

Until I found Finit I had always been in awe of those venturing into the realm of PID 1. However, learning from the simplicity of Claudio’s code I realized that although PID 1 at times is indistinguishable from magic, it is really not that hard to master. My version of Finit is available on GitHub.

The code is open sourced under the very liberal MIT/X11 license, and much of its frog DNA has proven very useful to me over the years. This blog post is about how that frog DNA can help you fill gaps in your projects …

HowTo: Push to Multiple GIT Repos With One Command

So, now that I have setup as a backup GIT repo to, I needed a simple way of always pushing to both repos – best way for me is to always hook into my regular work flow, otherwise I’d just forget. The git-remote(1) man page describes the new set-url --add sub-command:

git remote set-url --add origin

Now, with a simple git push followed by git push --tags I had now pushed to both the GitHub repo as well as my own server!

HowTo: Apache With Gitweb on Debian 8.1

I’m posting this in case anyone else gets stuck setting up Apache with Gitweb. Also as a reminder to myself in case I ever need to set up this all over again.

  1. You have all your eggs in one basket (GitHub), and
  2. You really like that shiny basket, but
  3. You know you’re clumsy and usually drop baskets yourself.
  4. You are wise (yes you are!) and realize you need another basket, so
  5. You set up a server and a domain yourself …

OK. Let’s start simple, since you are already running the latest Debian you fire up the command line and install the basics:

sudo apt-get install gitweb apache2

So it’ll complain, you’ll clarify your request and soon all required packages are on your server. Now what?

Debian has already set up http://localhost/gitweb for you, and if you have a domain already you should go ahead and edit the master file for that:

editor /etc/apache2/sites-available/000-default.conf
service apache2 reload

If you want to use that for your gitweb needs, then you’re done!

Inetd Support in Finit v1.12

A steady flow of features, and releases, is key to keeping any project alive. Recently I ticked off another item in the Finit TODO list …

Finit v1.12 now comes with a built-in inetd! You no longer need an external inetd daemon to launch services on demand.

The good news doesn’t stop there, this little inetd actually supports a poor man’s tcpwrappers!

inetd ssh/tcp          nowait [2345] /sbin/dropbear -i -R -F
inetd ssh@eth0:222/tcp nowait [2345] /sbin/dropbear -i -R -F

With these two lines in your /etc/finit.conf you tell finit to launch the Dropbear SSH server on demand on port 22 (default ssh/tcp port in /etc/services) on all interfaces except on eth0, which in your case is the Internet (WAN) interface, here you want SSH to run on port 222. Actually, you don’t want port 22 open at all on eth0 … so finit takes care of this for you! Seriously, it just works, no need for messing about with that nasty old iptables anymore!

The original UNIX inetd super server supported many protocols internally, some of which may seem a bit odd today, and some have been superseded by more modern protocols.

Finit currently only supports one internal/built-in standard service, time. It is built as a plugin to serve as an example of how you can extend Finit yourself. The time service can be called either as UDP or TCP. To prevent security issues, the time protocol is disabled by default. To enable it you need two things:

  1. The plugin (built by default)
  2. An inetd time ... line in /etc/finit.conf

Assuming you’ve installed the default set of plugins, the following two lines can be added:

inetd time/udp   wait [2345] internal
inetd time/tcp nowait [2345] internal

This can be very useful for testing the inetd capabilities, your network connection, or simply to get the time to a client where NTP for some reason does not work, or is blocked. For instance, you could have a GPS setup on your server and distribute time to clients with the time protocol.

To use it you need an rdate client. Users of rdate in BusyBox may need to be reminded that it only supports TCP.

$ rdate -pu
Sat Mar  7 08:48:58 CET 2015

For more info on Finit and its features, see the README.

Enjoy! ツ

Finit v1.11 Released!

Update 2015-03-09: This release has unfortunately been yanked due to serious regressions in launching background processes. It has been replaced by v1.12

Rant: All the C Compiler Warnings …

“Enable all the warnings!”

This is one of the truths you learn when you start working with C. Most of the time adding CPPFLAGS="-W -Wall -Werror" is all you need to find all the nasty bugs. And if that’s not enough, there are tons of tools for static code analysis, like scan-build in Clang, and Coverity Scan, to help you find all the bugs!

However, these pesky warnings (some of which cannot even be disabled!) are sometimes more of a nuisance than help. Sometimes you know that some parameters to a function will remain unused – it’s a callback, and you don’t need all the data given to you. So you start adding all kinds of voodoo, like __attribute__ ((unused)) … seriously?

Recent Open Source Work

I’m a coder, not a writer. Here’s what I’ve been working on during the winter holidays:

  • A new feature release of Finit is coming shortly, which will use libuEv and feature inetd support built-in!
  • Another minor release of my own take on event loops, libuEv v1.0.3. This time with a heavy focus on documentation and Q&A, extensive validation testing have been done on this release.
  • Released another minor release of mrouted, v3.9.7, which despite its age, and all other obvious limitations of DVMRP, is still one of the best options for dynamic multicast routing available today.
  • Major new release of pimd, v2.2.0, which is likely the last release ever of the old pimd, unless someone starts paying me to work on it.

    … or more people step up to help. Both the Xorp PIM-SM and the upcoming Quagga PIM-SSM implementations are in better shape. The only thing old pimd has got going for it is the license. It’s 3-clause BSD, so very liberal.

If you’re interested in pitching in, on any of my projects, just send me an email or connect with me on GitHub!

Blog Restoration Project

I’ve had this long-standing issue with backups. It’s deadly boring to set up and maintain, so I don’t do any. Until today!

Today I moved the sources for my Octopress blag to GitHub, which also prompted me to set up a mirror on GitHub Pages. As usual, reading up on the subject and muster enough motivation took me about three months, whereas the actual work took about 4h.