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autossh is a program to start a copy of ssh and monitor it, restarting it
as necessary should it die or stop passing traffic.
o The idea is from rstunnel (Reliable SSH Tunnel), but implemented in C.
o The author's view is that it is not as fiddly as rstunnel to get
to work.
o Connection monitoring using a loop of port forwardings or a remote
echo service.
o Backs off on rate of connection attempts when experiencing rapid
failures such as connection refused.
