rob
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Homepage: http://www.spoofedpacket.net
Posts by rob
Followup to ng_fec saga
May 18th
So everything seems to have remained stable over the past few days – and theres now a commit to the ng_fec code:
Deadly! 
IPv6 and ng_fec
May 15th
We managed to finally (hopefully) fix an annoying problem with one of our FreeBSD boxes and IPv6.
For some background; we used the ng_fec (4) device on FreeBSD 6.2-RELEASE to make a logical network interface out of two physical interfaces. This is referred to as bonding on Linux, IP Multipathing on Solaris and I think Cisco call it Ether Channel. Whatever way you go about it, the end result is that you get a network interface that is reachable via a multiple different paths. If each physical interface is plugged into a different switch, you get a nice amount of resiliency.
This works great in FreeBSD with ng_fec, however if you try to use an IPv6 address on the logical interface thats where things start to get interesting. Without getting into too much detail – the problems relate to how IPv6 maps IP addresses to MAC addresses, this is done by way of “neighbour advertisement” messages sent via multicast. However the ng_fec driver was not telling the physical network interfaces to join the correct multicast groups so these neighbour advertisement messages could not be processed correctly, which led to very flaky and mostly unavailable IPv6 connectivity. From what I can gather, you can use other drivers in -CURRENT that don’t exhibit this problem.
But with some diagnoses and a patch to ng_fec.c from Dave Malone we managed to correct the issue. This may make it up into the FreeBSD source tree at some point.
Hopefully things will stay stable from now on
Edit: Ah, there is a bug report raised for this already.
Eins Zwei Polizei..
Apr 23rd
I saw this video the other day for Eins Zwei Polizei by the Italian techno group Mo-Do:
It reminded me of the heady days of MTV Europe back in the early 1990s when all sorts of dodgy euro pop used to be shown and production values were cheap
Ah such cheesiness..
From the desk of Mrs Maureen Haughey…
Apr 17th
Normally these things are two-a-penny and I don’t pay too much attention to them, however
there is a 419 scam doing the rounds at the moment that can’t have any other purpose than to
entertain:
…The Irish government thinks it can shave and reduce me to a poor widow but I have the winning ace.A few years ago, when we weren’t sure if my Charlie would be convicted, he kept some money in trust for me in a Security and Finance company. He did not open the account in our names so it will not be traced to us to enable the past remain the past. The name on the account is Cedric de Vregille. I never thought Charlie would leave me so soon and it never occurred to me to ask if this name were fictitious or not or a name of any of his friends. I have tried to find this man but to no avail. The amount he deposited in this name is 30,000,000 (Thirty Million Euros)…
Read the full thing here.
Virtual sound channels in FreeBSD
Apr 11th
Following on from my earlier post about nspluginwrapper and Firefox; I noticed that the plugin likes to keep its file handles open even after you’ve finished viewing a flash-based site. This is a bit of an issue with things like the sound device – /dev/dsp0:
[rob@tachikoma] >> fstat | grep dsp
rob mplayer 80327 9 /dev 45 crw-rw-rw- dsp0.1 w
rob npviewer.bin 80305 63 /dev 42 crw-rw-rw- dsp0.0 rw
rob npviewer.bin 80299 63 /dev 42 crw-rw-rw- dsp0.0 rw
So if you happen to forget about this and go to play an mp3 or something later on, you’ll be left scratching your head. I didn’t feel like running a sound daemon like esound or arts, luckily FreeBSD has a kernel-based solution to this problem in the form of virtual sound channels which can be configured using the standard sysctl MIBs.
So we’ll try to allocate out 4 virtual sound channels:
[rob@tachikoma] >> sudo sysctl hw.snd.pcm0.vchans=4
hw.snd.pcm0.vchans: 0
sysctl: hw.snd.pcm0.vchans: Device busy
Oops, of course we must first close any programs that are using the sound card.
[rob@tachikoma] >> sudo sysctl hw.snd.pcm0.vchans=4
hw.snd.pcm0.vchans: 0 -> 4
[rob@tachikoma] >> sudo sysctl hw.snd.maxautovchans=4
hw.snd.maxautovchans: 0 -> 4
hw.snd.pcm0.vchans is the number of virtual channels pcm0 has and hw.snd.maxautovchans is the number of virtual channels given to new devices. All the virtual channels are automagically allocated using devfs.
I was then able to view flash sites, and open up audio applications afterwards without any problems – I’m starting to see the benefits of the move to devfs