DynFW for ipchains constantly checks /var/log/messages for packets denied by ipchains and responds by temporarily setting up firewallrules that deny any access from the originating IPs. Optionally it can do an ident lookup before setting up the rules.
You can download it from the following link: https://packetstormsecurity.com/files/download/10447/dynfw.tgz
Source: https://packetstormsecurity.com/files/10447/dynfw.tgz.html