knock (1) Linux Manual Page
knock – port-knock client Synopsisknock [options] <host> <port[:proto]> [port[:proto]] … Descriptionknock 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…
