Fwknop Port Knocking Utility

fwknop implements an authorization scheme that requires only a single encrypted packet to communicate various pieces of information, including desired access through a Netfilter policy and/or specific commands to execute on the target system. The main application of this program is to protect services such as SSH with an additional layer of security in order to make the exploitation of vulnerabilities much more difficult. The authorization server works by passively monitoring authorization packets via libpcap.