Simple Fail2ban Config for mystic bbs mis telnet server

First create the filter file in /etc/fail2ban/filter.d/mysticbbs.conf, with this content:

# Fail2Ban filter for Mystic BBS


before = common.conf


_daemon = mis

failregex = ^%(__prefix_line)s.*TELNET .*Auto banning IP <HOST>$
ignoreregex =

Then add this to your jail.conf or jail.local, adapt paths as needed:

enabled = true
port = 23
protocol = tcp
filter = mystic
logpath = /mystic/logs/mis.log
maxretry = 1

Finally, reload fail2ban using fail2ban-client reload