knock (1) - Linux Manuals

knock: port-knock client

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.

-d <t>, --delay <t>

Wait <t> milliseconds between each port hit. This can be used in situations where a router mistakes your stream of SYN packets as a port scan and blocks them. If the packet rate is slowed with --delay, then the router should let the packets through.

-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

AUTHOR

Judd Vinet <jvinet [at] zeroflux.org>