+++ /dev/null
-fwknop stands for the "FireWall KNock OPerator", and implements an authorization
-scheme called Single Packet Authorization (SPA) that is based around packet
-filter and libpcap.
-
-SPA requires only a single encrypted packet in order to communicate various
-pieces of information including desired access through a packet filter's policy
-and/or complete commands to execute on the target system. By using packet filter
-to maintain a "default drop" stance, the main application of this program is to
-protect services such as OpenSSH with an additional layer of security in order
-to make the exploitation of vulnerabilities (both 0-day and unpatched code) much
-more difficult.
-
-With fwknop deployed, anyone using nmap to look for sshd can't even tell that it
-is listening; it makes no difference if they have a 0-day exploit or not.