fail2ban not working on fresh install of ubuntu 14.04, why?

not sure if related but I deleted and recreated /var/log/auth.log, because I needed to empty it, to debug the situation

This could well be the problem. It's likely that the syslog daemon is still writing to the original fd. You should try restarting the syslog daemon to see if it starts to log to the correct file.

service rsyslog restart

Once you have messages going to the auth.log it should start working.

Sometimes this is because the __bsd_syslog_verbose is wrong. fail2ban expects /var/log/auth.log to start with YYYY.MM.DD (ie: 2014.10.15) yet the logs read MMM DD (ie: Oct 15)

To fix this you will need to do the following:

cp /etc/fail2ban/filter.d/common.conf /etc/fail2ban/filter.d/common.local

Edit common.local and set:

__bsd_syslog_verbose = (<[^.]+ [^.]+>)

Restart fail2ban :

Ubuntu (don't use restart):

sudo service fail2ban stop
sudo service fail2ban start

Issue in pyinotify:

https://github.com/fail2ban/fail2ban/issues/878

in /etc/fail2ban/jail.conf or /etc/fail2ban/jail.local

I changed "backend = auto" to "backend = polling" and everything works as expected ;)

service fail2ban stop
service fail2ban start