debian man page for knock

knock(1)																  knock(1)

NAME
       knock - port-knock client

SYNOPSIS
       knock [options] <host> <port[:proto]> [port[:proto]] ...

DESCRIPTION
       knock  is a port-knock client.  It sends TCP/UDP packets to each specified port on host, creating a special knock sequence on the listening
       server (see the knockd manpage for more info on this).

OPTIONS
       -u, --udp
	      Make all port hits use UDP (default is TCP).  If you want each port to use a different protocol (TCP or UDP), then you  can  specify
	      the protocol on a per-port basis.  See the example below.

       -v, --verbose
	      Output verbose status messages.

       -V, --version
	      Display the version.

       -h, --help
	      Syntax help.

EXAMPLES
       knock myserver.example.com 123:tcp 456:udp 789:tcp
       knock -u myserver.example.com 8284 4721 18592 42912

SEE ALSO
       knockd is the accompanying port-knock server.

AUTHOR
       Judd Vinet <jvinet@zeroflux.org>

knockd 0.5							   June 26, 2005							  knock(1)