ssh-knock — Drop-in ssh wrapper for accessing a doormand(8) port knocking protected sshd(8) server.
ssh-knock is a drop-in wrapper for ssh(1) when the remote sshd(8) service is protected by the doormand (8) port knocking daemon.
ssh-knock accepts ssh(1) option and arguments, from which it extracts the necessary arguments for knock(1) which is then invoked to knock(1) It is intended to be used in all places where the ssh(1) client is normally used.