log2command was created as a sort of reverse fail2ban or cheap VPN-firewall: a machine with a closed firewall can be told, by a foreign machine, to accept connections from a specific IP. log2command then keeps track of the Web server log file and watches for inactivity from the user's IP. After an amount of time, another command is executed that can remove the user's IP from the firewall, closing down the machine again. The PHP script is a command line program that can be run in the background.
agentsmith is a daemon that continuously monitors a log file for break-in attempts by remote hosts. Upon detection of a break-in attempt, it launches a user defined script or application, which can do virtually anything from sending mail messages to whatever else you might think of. The criteria for what is considered a break-in attempt can be configured by means of a regular expression.