File: //usr/share/doc/autossh/README.Debian
autossh for Debian README
=========================
autossh is wrapped to choose a random port or fall back to 21021 the real
binary is /usr/lib/autossh/autossh
In this version of autossh the commandline switch -M overrides AUTOSSH_PORT
environment, as opposed to default upstream behaviour (see
http://bugs.debian.org/238150#msg6 and following)
Note: if your ssh client/server version is recent enough you can obtain similar
behaviour by setting ClientAliveCountMax and ServerAliveInterval in
/etc/ssh/sshd_config. See sshd_config(5).