Fail2ban can be used to rate-limit nearly all services that have the potential for abuse. I have it set up to track connection and message frequency, bans on me

Fail2ban can be used to rate-limit nearly all services that have the potential for abuse. I have it set up to track connection and message frequency, bans on message content (not following protocol, overly large, malformed, etc) and so forth. Having a system like F2B is nice because it compartmentalizes abuse handling and you can set up rules in one place for all your services, both user-facing and not. Since the rules/actions are user defined, anything is possible -- I've had actions that send alerts to Twitter, a system that distributes bans to hundreds of servers, and centralized logging that gives very good insight into how users are poking around.