The dot at the ignoregex did not belong there. Somehow it was added during the copying and pasting. Thanks for reporting it, I did not see it. Otherwise, empty ignoregexes are in all filters, and if they are missing, fail2ban client shows warnings when starting the filter, which I prefer avoiding.
I am sorry, I installed the Win GIT, but still did not learn how to work with it, so am posting here again. This time, I'll avoid posting two pull requests, so please fix the dovecot.filter for me, if you don't mind.
This current filter does not match authentication errors in my Dovecot logs (two different lines attached). First of all the session string is at the end (after the optional TLS string), and not before it as it is now in the filter. I don't see it anywhere in the other logs here in the opposite order, hence I assume it is the rule for all installations. And then, the session ID can include also other characters than those matched by \w+ (i.e. the slash and the plus signs in my case), hence it needs to be \S+ instead. Personally, I'd do the regex much less restrictive than it is, but if I follow the current logics, the following form works:
<pre>^%(__prefix_line)s(pop3|imap)-login: (Info: )?(Aborted login|Disconnected)(: Inactivity)? \(((no auth attempts|auth failed, \d+ attempts)( in \d+ secs)?|tried to use disabled \S+ auth)\):( user=<\S*>,)?( method=\S+,)? rip=<HO
ST>, lip=(\d{1,3}\.){3}\d{1,3}(, TLS( handshaking)?(: Disconnected)?)?(, session=<\S+>)?\s*$</pre>
As explained in https://github.com/grooverdan/fail2ban/pull/4, in Exim there can be used plenty of other standard authentication names, and in fact the names can be custom. The failregex in Exim filter should catch authentication errors regardless of the name of the authentication. Hence replacing the plain|login with the general \w+
When using Dovecot authentication for Exim, which is relatively common, the current regex for catching authentication failures needs a small tweak. The current plain|login options are too limiting and will only work in the cases when only the Exim's rudimentary built-in authentication is used. There can be not only the dovecot_login shown in this log example, but also dovecot_plain, ntlm, cram, cyrus, md5, and plenty of others. In fact many admins may opt for their own authentication labels, when setting up Exim. For this reason the regex should catch any label. I suggest modifying the regex in the following way:
<pre>^%(pid)s \w+ authenticator failed for (\S+ )?\(\S+\) \[<HOST>\]: 535 Incorrect authentication data( \(set_id=.*\)|: \d+ Time\(s\))?\s*$</pre>
Ivo Truxa