fwknop: fwknop (FireWall KNock OPerator)
fwknop: 
fwknop: fwknop implements an authorisation scheme called Single Packet
fwknop: Authorisation (SPA). This method of authorisation is based around a
fwknop: default-drop packet filter using iptables and libpcap.
fwknop: 
fwknop: The main application of this program is to protect services such as
fwknop: SSH with an additional layer of security in order to make the
fwknop: exploitation of vulnerabilities (both 0-day and unpatched code) much
fwknop: more difficult.
fwknop: