One of the realities of having public facing SSH is the continual brute force attempts. I have 3 droplets at DigitalOcean, SGP1 and NYC2 get hit much more often than LON1. I thought about deploying SSH ACLs through SaltStack, but because all my systems are keys only, instead I deployed fail2ban with a custom configuration file to watch the bots get banned and laugh maniacally.
The relevant parts of config were as follows:
base: 'os:debian': - match: grain - settings.ntp.debian - settings.minion.debian - settings.fail2ban.debian
fail2ban: pkg: - installed service: - running - require: - pkg: fail2ban - watch: - file: /etc/fail2ban/jail.local /etc/fail2ban/jail.local: file: - managed - source: salt://settings/fail2ban/jail.local - require: - pkg: fail2ban
This deploys a custom jail.local file, which is the recommended way for deploying fail2ban.
This makes it quite easy to change ban times globally, or based on other grains.