Install conntrack tools on Centos 5
Conntrack tools allows manipulating linux connection tracking table. Command conntrack is useful for deleting conntrack entries, but it is not included by default in RHEL/Centos.
Dotdeb packages unattended upgrade
Unattended upgrades in Debian will not upgrade packages from third-party repositories (for example dotdeb.org) by default. It can be easily enabled editing /etc/apt/apt.conf.d/50unattended-upgrades.
Catching unsolicited bounces (backscatter) with SpamAssassin
From http://wiki.apache.org/spamassassin/VBounceRuleset
The “Virus Bounce Ruleset” is a SpamAssassin ruleset to catch “backscatter”.
Backscatter is mail you didn’t ask to receive, generated by legitimate, non-spam-sending systems in response to spam.
Track Dovecot User Last Login Date and IP Address
Idea how to implement tracking last user pop3 or imap login date using dovecot is described in Dovecot Wiki.
Server side mail filtering with dovecot and squirrelmail
Maybe you know, maybe not, but pre-build Debian Lenny packages of dovecot from backports has been built with sieve plugin.
Digmia Centos repository
Digmia Enterprise Linux Source is repository with many interesting and actual packages for Centos (RHEL). It contais for example mysql-5.0.84-2.el5.x86_64.rpm, php-5.2.10-2.el5.x86_64.rpm, zabbix-1.8.3-2.el5.x86_64.rpm, postgresql-8.2.14-1.el5.x86_64.rpm and many more.
How to change Currently Active Slave when runnning bonding in active-backup mode
When you are running bonding in active-backup mode, you can detect which slave is active by listing /proc/net/bonding/bond0. How to change active slave?
ethtool: offloading
Enable stateless offloads to improve system performance.
Stateless offloads, such as checksum offload, segmentation offload, and large receive offload, can improve system performance by moving some of the processor-intensive tasks that do not require a connection to the network adapter.
Recovering deleted lvm volume
LVM is a logical volume manager for the Linux kernel; it manages disk drives and similar mass-storage devices, in particular large ones. The term "volume" refers to a disk drive or partition thereof.
Every LVM operation makes backup of lvm metadata. Metadata archive stored in directory /etc/lvm/archive/ in easily readable text files. Each operation creates own metadata backup file, with information when it was created. For example: