Your intentions are good, rotating your fail2ban log file. You are rotating your fail2ban log file, right? I mean, it’s not done by default for some weird reason so I’d forgive you if you aren’t. They get big and they should be trimmed and archived. If you’re already rotating your fail2ban log file or you’ve tried doing it in the past, did you ever notice that fail2ban stops using those rotated files? How rude! Let’s fix that.
Most every program you install and run, especially services, generate some form of log file and nearly everyone only checks those logs when something bad happens. Why? Because there are so many logs to check! Well, that’s where a log parsing program can be a lifesaver. I like using Logwatch on my Debian/Ubuntu systems. Logwatch is a nice, lightweight, easy-to-use program that generates a summary report that can be emailed nightly or on whatever schedule you choose.