Daemon Shield

Linux is an excellent operating system to deploy in the roles of firewall and web server. Low and no cost options are available and it requires very few system resources to do a lot of work. Because it often is deployed on the "edge" of the network, it can be a target for brute force attacks.

Daemon Shield is a program that scans the log files and shuts out IP addresses that appear to be performing brute force attacks. It works for SSH and PAM modules and lives in the background. Highly recommend as a complement to normal security precautions such as strong passwords and limiting exposed services.