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.

       -4, --ipv4 <version>
              Force usage of IPv4.

       -6, --ipv6 <version>
              Force usage of IPv6.

       -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>