Any service that is connected to the internet is a potential target for brute-force attacks or unwarranted access. There are tools like fail2ban or sshguard, but these are functionally limited because they are only parsing log files. Blacklistd takes a different approach. Modified daemons like SSH are able to connect directly to blacklistd to add new firewall rules.
Abuse Contact DB is a proxy database service for people who want to report network abuse directly to network owners, without getting lost in the whois databases or get rate-limited by whois servers. It is an easy-to-handle mechanism that allows you to look up abuse contact email addresses from which abusive content was sent by searching for an IP address.
Setup a simple Bot Trap for your website or web application that can enhance the security of your server and prevent malicious bots or script kiddies from poking around by luring them into a trap and banning with fail2ban.