Git Daemon - "who's been sitting on my port?"

Stuck in Germany this weekend by the snow back home, I went into work today (Saturday) to make up some lost time (already!) and get an extra day's billing (yay contracting!!)

I've been doing some work on our SUSE9 servers with the Git DVCS, and I've had no trouble setting up the daemon process which is needed to allow external users access to your shared repositories - just run git daemon --detach and you're pretty much done.

Today I wanted to do the same thing on a SUSE10 server.  I'd had to build Git from source for SUSE9, but the opensuse website provided a pre-built RPM for version 10, which saved some messing around.  Unfortunately it caused some more as well...

The problem I had was that git daemon would run okay on the server, but git clone on the client kept telling me that the remote had closed the connection.  Even plumbing commands like git ls-remote failed.  Very strange.

Rolling up my sleeves, telnet server 9418 showed me that something was listening to the default Git port, but what?

I thought I would get the answer using the netstat program.  I usually run this with the -r (--route) flag to look at the routing table when I'm trying to work out why computers won't talk to each other, but today I used -l (--listening), -t (--tcp) and -p (--program) on the server to see who was listening to which ports.  It was partially successful, because one line identified the local address as *:git, but it listed the program name as "-".  Great - I already knew something was listening to the Git port!  Though it was interesting that the name "git" was listed rather than the port number "9418" as this showed that something had updated /etc/services to list the port name (in hindsight I suspect the RPM installer did it).

Google came to my aid, locating this post about auditing open ports.  The author talked about the netstat command which I already knew about, but also mentioned lsof, which was new to me.  Although the name stands for "list open files" it also list ports that are being listened to.  Piping the output through grep soon showed me that xinetd was listening to the Git port.  QED.  But why?  I hadn't set it up (or so I thought).

On SUSE10, xinetd is initialised from /etc/xinetd.conf which in turn reads all the configuration files in the /etc/xinetd.d directory.  And what should be there but a file called git, telling xinetd to listen to port 9418 and launch the git daemon process to handle requests.  This file was dropped in place by the git-daemon RPM I'd downloaded earlier.  Gotcha!

Not surprisingly the configutation didn't match my needs as it used the --base-path flag to limit the daemon to serving repositories under the /srv/git directory, which didn't exist on my system.  A quick edit with vi to correct the path, followed by service xinetd restart to load the new config, and everything was working.  Job done.

One good thing to come out of this is that I've seen how easy it is to set up git-daemon to run from xinetd, so I'll be able to do this on the SUSE9 machines too rather than messing around with a cron job to start and monitor the process.  This will save me more time than I lost investigating the problem.

Listen to BBC Radio with Ubuntu using Rhythmbox

Sitting in my flat in an almost snowless Germany, I decided to save my iPhone's battery and listen to Radio 6 on my laptop instead.  Linux has been getting better and better, and the Ubuntu 9.10 Karmic Koala release is so usable that I haven't booted into Windows for a couple of months.  So how difficult could it be to play a BBC internet radio stream?  Not too hard, as it turns out, but a bit of effort is required...

The simple way is to fire up your favourite browser (Firefox is mine), click to bbc.co.uk/radio select the station you want and click Listen Live.  Up pops the BBC iPlayer window and away you go.  But that was too easy...

Ubuntu comes with a standalone musicplayer, Rhythmbox, which I thought would be a better bet.  This proved a bit more challenging.  A quick search with the ubiquitous web scraper found the wonderful Beebotron site, whose mission is to provide iPlayer-less links to BBC radio streams so you can listen to them with your weapon of choice.  I soon found that Radio 6 can be heard at http://bbc.co.uk/radio/listen/live/r6.asx, but pasting this link into Rhythmbox met with silence.

 Back to the web trawler, and up popped an article on the Ubuntu Forums website.  It seems that the BBC are moving their streams to the proprietary WMA format, which is not supported by a default Ubuntu installation.  You need to install the ubuntu-restricted-extras package to get the necessary codecs.  (Bizzarely, the package installation link on that page didn't work when I clicked on it in Firefox, so I fired up the Synaptic Package Manager and did it from there instead).

I thought that would be it, but the stream still wouldn't play, so I reverted to the tried-and-trusted "if it don't work, reboot" mentality that's been ingrained by years of exposure to Windoze.  Hey Presto!  Rhythmbox is now pumping out Radio 6 as I type this post.  Job done.