OpenSSH: Difference between revisions
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OpenSSH is a powerful, open-source implementation of the Secure Shell protocol. | OpenSSH is a powerful, open-source implementation of the Secure Shell protocol. | ||
==Connection multiplexing== | |||
OpenSSH 4.0 added connection multiplexing, which can tremendously accelerate ssh connection setup. I discern no weaker security here than that accepted when forwarding an agent -- root on the target machine can take advantage of the control named pipe created, unless the "ask"/"autoask" properties are used (and even then, they could be snooping memory...). There's some serious speed wins to be had:<pre>[recombinator](127) $ \time -f %E ssh -oControlPath=none hogwarts true | |||
0:01.44 | |||
[recombinator](0) $ \time -f %E ssh -oControlPath=none hogwarts true | |||
0:01.65 | |||
[recombinator](0) $ \time -f %E ssh -oControlPath=none hogwarts true | |||
0:01.68 | |||
[recombinator](0) $ \time -f %E ssh -oControlPath=none hogwarts true | |||
0:01.61 | |||
[recombinator](0) $ \time -f %E ssh hogwarts true | |||
0:00.26 | |||
[recombinator](0) $ \time -f %E ssh hogwarts true | |||
0:00.20 | |||
[recombinator](0) $ \time -f %E ssh hogwarts true | |||
0:00.20 | |||
[recombinator](0) $ \time -f %E ssh hogwarts true | |||
0:00.22 | |||
[recombinator](0) $ </pre> | |||
Just set <tt>ControlPath</tt> to something like <tt>~/.tmp/ssh/%r-%l-%h-%p</tt> (make sure the directory exists!), and <tt>ControlMaster</tt> to <tt>auto</tt> or <tt>autoask</tt>. Display and agent forwardings will be available to all multiplexed connections, but (at least as of 5.2) it is impossible to forward multiple displays or agents. | |||
==External Links== | ==External Links== | ||
* [http://www.openssh.com/ OpenSSH] home page | * [http://www.openssh.com/ OpenSSH] home page | ||
* [http://www.monkey.org/~provos/scanssh/ ScanSSH] home page | * [http://www.monkey.org/~provos/scanssh/ ScanSSH] home page | ||