Fail2ban installation 24.04LTS

OK lets bolt down a bit against brute force SSH attacks from the internet idiots, before we go any further.

sudo apt install fail2ban
sudo systemctl stop fail2ban.service

The fail2ban service keeps its configuration files in the /etc/fail2ban directory. There is a file with defaults called jail.conf. Since this file can be modified by package upgrades, we should not edit this file in-place, but rather copy it so that we can make our changes safely.

We need to copy this to a file called jail.local for fail2ban to find it:

sudo cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local

Once the file is copied, we can open it for editing to see how everything works:

sudo nano /etc/fail2ban/jail.local

We can make a few changes to make things work better.

# "ignoreip" can be an IP address, a CIDR mask or a DNS host. Fail2ban will not
# ban a host which matches an address in this list. Several addresses can be
# defined using space separator. Here I add exceptions for bans
ignoreip = 127.0.0.1/8 10.3.200.0/24

# "bantime" is the number of seconds that a host is banned.
bantime  = 604800

# Destination email address used solely for the interpolations in
# jail.{conf,local} configuration files.
destemail = mark@scottworld.net

#
# Name of the sender for mta actions
sender = root@scottworld.net

# Choose default action.  To change, just override value of 'action' with the
# interpolation to the chosen action shortcut (e.g.  action_mw, action_mwl, etc) in jail.local
# globally (section [DEFAULT]) or per specific section
action = %(action_mwl)s

Restart fail2ban service

service fail2ban restart