At times denyhosts is being recommended over fail2ban. The common misconception being these applications are equal. They're not, OK in more than one way, but focusing on method of filtering denyhosts uses tcp_wrappers by default where Fail2ban uses iptables by default.
Using tcp_wrappers means a packet has to be delivered to that service. The serving application is responsible for reading /etc/hosts.{deny,allow} to determine itself if a connection is allowed or not. Requiring a network...
