knock (1)

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

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).

-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.

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

knockd is the accompanying port-knock server.

Judd Vinet <[email protected]>