Introduction

Why is port knocking (PN) useful?

firewalling is great... but it lacks some flexibility port knocking brings you easily.

1. You might need to access your services from places you did not configure access for
2. You might want to prevent brute players to try repeatedly your services ports again and again. With PN they're closed, except for you.

What port knocking is not

It's not THE ultimate securing solution. It's just another layer preventing DIRECT access to specified port(s). After knocking you still might want to use good security practices to enable access to your services (i.e. disable root login w/ SSH, force certificate usage as much as possible, VPN your connections, etc.)