monline

For quite a few years now most linux distributions ship udev with a network interface name caching mechanism. This simply means that whenever udev assigns a name for a network interface, it's cached (based on the interface's MAC address) in /etc/udev/rules.d/70-persistent-net.rules. However if you're cloning a system, the copy still contains this cache file. And since it lists your common interface names (from the original/source system) like eth0 or eth1 as occupied by specific MAC addresses, the cloned system will get new interface names (eg. eth2, eth3, rename3, etc.). Obviously this will break everything that references the old names and most of the time this will result in no network in the cloned system.

Works like a charm, even on Debian Squeeze. You just have to add the Sid repository and specify a low priority in your APT configuration via a new /etc/apt/preferences.d/debian-sid file, like this one ...

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 howto 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.