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One of the most impressive SSH tricks I've seen is the ControlMaster option. It saves your authentication information on a per-(user, host) basis, which lets y

by leif 16y ago

One of the most impressive SSH tricks I've seen is the ControlMaster option. It saves your authentication information on a per-(user, host) basis, which lets you share one connection among multiple ssh/scp/rsync commands and TRAMP sessions. This is less useful if you use passwordless keys or ssh-agent (please use ssh-agent), but becomes much more useful if the host you connect to doesn't support key-based auth. # multiplex connections to one host ControlMaster auto # where is that file ControlPath ~/.ssh/master-%r@%h:%p Other useful things in my .ssh/config, check the manpages before you use them: # use compression Compression yes # really really compress it CompressionLevel 9 # forward X stuff ForwardX11 yes # yes, really forward X stuff ForwardX11Trusted yes

jcsalterego 16y ago
The only issue I had with ControlMaster, IIRC, was that when I killed the original connection, it would take everything else down with it. There's a good chance I was just doing it wrong™ though.
- leif 16y ago
  The behavior I've seen is that when you log out, the process doesn't end until all other clients to the connection have exited. I've observed what you describe if I then ^C it. The way I usually do it is by opening something over TRAMP before opening any other ssh windows. That way, Emacs will handle the connection maintenance and I don't really need to see that it's up. If it dies, I just try saving something and it'll re-establish the connection. If you don't use Emacs, you can always just start a dummy connection first and minimize/disown it.
  - jcsalterego 16y ago
    That sounds about right. Good tip about TRAMP, although I tend to exit out of my emacs sessions frequently. For my long running ssh tunnels, I just screen them.
    - leif 16y ago
      Ahh, then you want to learn about emacs --daemon and emacsclient. :-)
mcmatterson 16y ago
For reasons others on this thread have outlined, ControlMaster is often more trouble than it's worth for general-purpose SSH usage. However for use in automated tools, it's a lifesaver. I use it extensively in doo for that exact reason: http://github.com/mtrudel/doo http://github.com/mtrudel/doo
Dobbs 16y ago
I have a pretty awesome script that uses control-master to allow me to type the password in once and then preform a bunch of actions. The script specifically is for boot strapping ssh authorized keys on boxes that can't be on puppet. I'd rather use ssh-agent for day to day work but this is a useful trick for scripting.
igorhvr 16y ago
> CompressionLevel 9 Just one note regarding the above line: this only works with SSH version 1. This functionality was removed in version 2 of the protocol (in the newer version there is only a single default compression level).

by leif 16y ago

jcsalterego 16y ago

The only issue I had with ControlMaster, IIRC, was that when I killed the original connection, it would take everything else down with it. There's a good chance I was just doing it wrong™ though.

leif 16y ago
The behavior I've seen is that when you log out, the process doesn't end until all other clients to the connection have exited. I've observed what you describe if I then ^C it. The way I usually do it is by opening something over TRAMP before opening any other ssh windows. That way, Emacs will handle the connection maintenance and I don't really need to see that it's up. If it dies, I just try saving something and it'll re-establish the connection. If you don't use Emacs, you can always just start a dummy connection first and minimize/disown it.
- jcsalterego 16y ago
  That sounds about right. Good tip about TRAMP, although I tend to exit out of my emacs sessions frequently. For my long running ssh tunnels, I just screen them.
  - leif 16y ago
    Ahh, then you want to learn about emacs --daemon and emacsclient. :-)

mcmatterson 16y ago

For reasons others on this thread have outlined, ControlMaster is often more trouble than it's worth for general-purpose SSH usage. However for use in automated tools, it's a lifesaver. I use it extensively in doo for that exact reason: http://github.com/mtrudel/doo http://github.com/mtrudel/doo

Dobbs 16y ago

I have a pretty awesome script that uses control-master to allow me to type the password in once and then preform a bunch of actions. The script specifically is for boot strapping ssh authorized keys on boxes that can't be on puppet. I'd rather use ssh-agent for day to day work but this is a useful trick for scripting.

igorhvr 16y ago

> CompressionLevel 9 Just one note regarding the above line: this only works with SSH version 1. This functionality was removed in version 2 of the protocol (in the newer version there is only a single default compression level).