Sentry (Bruteforce attack blocker) is described as 'Prevents Brute Force Attacks Against SSH, FTP, SMTP and More' and is an app in the Security & Privacy category. There are three alternatives to Sentry (Bruteforce attack blocker) for Linux and Mac. The best alternative is Fail2ban, which is both free and Open Source. Other great apps like Sentry (Bruteforce attack blocker) are SSHGuard (Free, Open Source) and Denyhosts (Free, Open Source).
The idea of denying access to SSH servers is nothing new and I was inspired by many other scripts that I discovered. However, none of them did things the way I envisioned them to. Also, they were all shell scripts which do not offer the elegance of Python.