OpenSSH has decent basic support for opportunistic connection sharing , but most of this is that ssh will look for anexisting master connection before making a new one. It could do betterand enable a true opportunistic connection sharing mode.

There's two problems with ssh's current support for this, one big andone small. First, being the master connection can keep your ssh running when it would otherwise exit. Second, the master connectionexits immediately when there's no active sessions running over it;there'

Following on the basic overview , here's how Iuse OpenSSH's connection sharing feature.

First, since I hate programs that don't exit when I want them to, Idon't let ssh automatically create connection masters. Instead Ialways explicitly create them myself, so that I can do so in a way thatharmlessly parks them in the background. So while I set a ControlPath (to a value mentioned in the previous entry ),I leave ControlMaster set to no , the default.

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Vaguely recent versions of OpenSSH have a feature where you can havemultiple independent sessions running over what is actually oneconnection, even though you ran several separate ssh commands. Theprimary advantage this offers is that new ssh sessions startsignificantly faster, since they don't have to go through all of thecryptography and authentication of a full ssh connection. (As a sidebenefit, there's fewer processes running on either side, since you nolonger need a ssh and an sshd for each active session.)

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