This guide will show you how to install and configure openDKIM on a Debian Squeeze VPS. DKIM is a signature/cryptography email authentication technology used to validate that a message was sent by an authorized source. DKIM allows an organization to take responsibility for transmitting a message, in a way that can be verified by a recipient. More information can be found at the official DKIM web site.
mod_evasive is an evasive maneuvers module for Apache to provide evasive action in the event of an HTTP DoS or DDoS attack or brute force attack. It is also designed to be a detection and network management tool, and can be easily configured to talk to ipchains, firewalls, routers, etc. mod_evasive presently reports abuses via email and syslog facilities.