monline

First of all: install exim
Now we have to reconfigure it, because by default it won't deliver any mails to any external address:

The following simple command will browse through the tree of the current directory for various archive files and test their integrity. If the test fails, it'll print the file's path. You can easily extend it by adding more filename patterns and tests.

In case of the Sun/Oracle JVM (JRE/JDK) the SSL certificates are store in this keystore: /etc/java-6-sun/security/cacerts. To update it, use the keytool utility that comes with the JRE/JDK.

The LDAPClientAuthentication page in the Ubuntu Community wiki describes the basic setup pretty well. However if you bring encryption (SSL/TLS) into the game, it's a quite different story.

With this Munin plugin you can monitor the DNS response times of specific queries. It uses dig to execute the DNS queries. You can specify multiple hostnames to query for and a separate DNS server for each query. Quite useful. I've added the hostnames (that you query for) to the labels in the generated Munin reports in the attached (modified) version of the plugin.

There's a very good how to on installing this particular Oracle RDBMS version on Ubuntu 11.10 here. However Ubuntu is not Debian, there're a few differences. Mostly you've to skip a few steps:

In Debian the default /etc/rsyslog.conf includes all *.conf files from /etc/rsyslog.d. The contents of these config files are read by rsyslogd before the default rules, so you easily override any defaults.

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. (...)