04:43 pm, 11 Jun 06
ssh multiplexing revisited
A year and a half ago I asked about ssh's multiplexing-related features. Today I thought to look for more information about this again. It still seems underdocumented.
But what I've figured out is that OpenSSH 4.2 now allows "opportunistic multiplexing". If you have
However, what I think I really want is something that actually leaves the master connection open for a few seconds after I log out. Then, stuff that does a series of sftp's or commands executed via ssh will be able to effectively pass the open connection along in between them, instead of opening up and tearing it down repeatedly like they currently do. (In particular, I'm thinking of arch/darcs over ssh.) I suppose that's what fsh is for, though...
But what I've figured out is that OpenSSH 4.2 now allows "opportunistic multiplexing". If you have
ControlMaster auto and a ControlPath ... set up in you ~/.ssh/config, the first time you connect to a host it creates and leaves open a (UNIX domain) socket that subsequent ssh's to the same host will use. This makes these connections come up much more quickly. (Here's more info.)However, what I think I really want is something that actually leaves the master connection open for a few seconds after I log out. Then, stuff that does a series of sftp's or commands executed via ssh will be able to effectively pass the open connection along in between them, instead of opening up and tearing it down repeatedly like they currently do. (In particular, I'm thinking of arch/darcs over ssh.) I suppose that's what fsh is for, though...
One of the issues I ran into with using multiplexing normally is that I tend to try to exit the master process too often :)
So when I sit down to work I run a script that fans out all of my master connections using password protected keypairs (thanks to keychain), then I drop the screen session and work as normal. Except all of my new connections happen 5x faster and scp transfers fly.