sshguard protects hosts from brute force attacks. It supports IPv6, whitelists and log authentication, interfaces with all the major firewalling systems, has a remarkably clever log analyzer, and is independent, fast and lightweight as it's written in C
On Ubuntu 14.04 sshguard fails to start when a blacklist is attempted (-b file). The code must exit errors with "0" (?) since there is not record of failure in auth.log -- just no mention of (re)start! I can't see any recent mails in the archives, so assume that this is no longer supported?