monline

Well, this is a classic one. The maintainer of the netbase package proposed a fundamental change in how network sockets should be managed regarding IPv4 vs. IPv6 (ie. IPv4-mapped IPv6 addresses). He suggested that the default of the net.ipv6.bindv6only kernel variable should be set to 1 (whereas the current default is 0). After "some" discussion (he and two other guys had something to say about the topic in a one and a half month period) he made the change on 6th December 2009.

It's really not that difficult, requires only a few tries with various repositories and APT configurations. First of all let's make something clear: when I say "up-to-date", I mean the latest release. To get this, we've to install ffmpeg from the sid (aka. unstable) packages of www.debian-multimedia.org.

Update (2011.12.23): I've added a few corrections to this post after applying it to a number of Debian Squeeze servers.

(...) Modern Linux distro's, say Ubuntu (8.10) comes with a default PHP configuration of session.gc_probability = 0. This means that in general, session GC will never run(!). There is a unix cron job that runs every half hour and checks for old sessions to delete (see more at /etc/cron.d/php5) but this is done only if you're using the standard "files" as your session handler (check out the directive of session.save_handler on your machine to learn what php default sessions handler is but make sure to check that your application doesn't overwrite this), so for Drupal users using plain Debian/Ubuntu, stock LAMP packages and stock Drupal applications, this means that the PHP garbage collection, despite your best intentions, will also never run. (...)

I've experienced the same 5 second long DNS lookups on a Debian 6.* (Squeeze) server using amd64 architecture and the options single-request in /etc/resolv.conf helped me too. Using strace -T ... on the command that exhibits the slow DNS behaviour you can easily identify the culprit.

One thing about APT pinning I've now learned for life is that you should always check the output of apt-cache policy. In various distributions and APT versions the pinning might behave a bit differently. Checking the output of apt-cache policy (note that there's no package name at the end of the command, thus it'll list your APT sources and their pinning values) reveals most probably the reason why your preferences file does not do whatever you wish it to do.

It seems Adobe finally realized that there's a significant Debian user base for their Flash Media Server and started to build "unofficial" Debian support in FMS (the "unofficial" means that the FMS scripts -install, startup, shutdown- still skip a few steps in case FMS runs on Debian). The installation is pretty much straightforward, no problems at all. It even checks for the availability of the libnspr4 library (and stops if does not find it) and creates the fms user and group for you (however I still suggest to create these manually since you want to have these in the system UID/GID range) and sets up automatic start on boot. The libnspr4 lib can be installed via apt-get install libnspr4-0d, the fms user and group can be created via addgroup --system fms; adduser --system --group fms and for the autostart to work right, you'll have to adjust the start/stop runlevels in /etc/init.d/fms after the installation finished and reset the runlevels of the fms script via update-rc.d fms remove; update-rc.d fms defaults (by default the /etc/init.d/fms script does not include runlevel 2 in the start runlevels and Debian's default runlevel is 2).

Unfortunately the dhcp3-client package in Debian does not support (yet) the sending of the configured hostname to the DHCP server. Ubuntu has a custom patch that makes this possible (it was added 4 years ago!), but the Debian package maintainer did not feel this to be important enough to add a patch to Debian's package too. The bugreport on the issue is now 9 years old and a solution for Debian users/admins is still not available (apart from hard coding the hostname into the DHCP client config file of course). It seems that the latest upstream version (>=4.2.0) of the DHCP client already contains support for sending the actual hostname to the DHCP server (btw. 4.2.0 was released in December 2009), but this will get into Debian only with the next major version (the one that'll follow Squeeze, currently codename "Wheezy"). No rush ... we can wait a couple of more years ... maybe a fix'll be available by the time my (future) kids try to install linux on their PC/mobile/watch/whatever. You've got to love Debian's "stableness". It's either that or you can try your luck with the ever changing (and breaking) Ubuntu. Unfortunately there's nothing in between. Of course one can always turn to a different distro ... RedHat, etc.

There're many-many methods described all over the net, some work in Etch, some in Lenny, some in Squeeze. The official documentation tells you to use sysctl to set net.ipv6.conf.all.disable_ipv6 to 1 in case of Squeeze.

Googling in the subject shows that you can downgrade PHP packages to Lenny versions without much trouble. However the already documented methods lacked a few things I consider important, thus I write down my own downgrade instructions for future reference.

The APT repository key of Oracle's OSS site has expired on 4th September (as probably many Debian/Ubuntu maintainers have found out by now). An apt-get update gave me the following error message:
The Oracle help page at Ubuntu's wiki contains the URL for the currently valid key.