Module monitor 

Testing that the tunnel still carries traffic.

Three arrangements, all set up by the -L/-R forwards this module hands to each ssh start:

• Loop — data written to the local monitor port travels to the remote, where the matching -R forward sends it straight back to a second local port that rash is listening on.
• Echo — data written to the local monitor port reaches an echo service on the remote, which returns it over the same connection.
• Unix — the loop again, but over UNIX-domain sockets, so there are no ports to choose and none to collide at either end.

The listening socket is opened once and held for the life of the process, as autossh does (autossh.c:465-472).

Modules

probe

The probe payload and the exchange that carries it.

Structs

Monitor

The live monitor.