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Create a persistent connection to a machine

Terminal - Create a persistent connection to a machine
ssh -MNf <user>@<host>
2009-02-26 14:11:19
User: raphink
Functions: ssh
40
Create a persistent connection to a machine

Create a persistent SSH connection to the host in the background. Combine this with settings in your ~/.ssh/config:

Host host

ControlPath ~/.ssh/master-%r@%h:%p

ControlMaster no

All the SSH connections to the machine will then go through the persisten SSH socket. This is very useful if you are using SSH to synchronize files (using rsync/sftp/cvs/svn) on a regular basis because it won't create a new socket each time to open an ssh connection.

Alternatives

There are 3 alternatives - vote for the best!

Terminal - Alternatives

Know a better way?

If you can do better, submit your command here.

What others think

I had tried this before running a command on one SSH and backgrounding it (ssh

user@host "command" &), but this is much nicer.

You can also set the options on the command line if you only want the control process for a single job:

ssh -o "ControlPath ~/.ssh/master-%r_%h_%p" -MNf

scp -o "ControlMaster no" -o "ControlPath ~/.ssh/master-%r_%h_%p" user@host:file .

(ControlMaster no is default, so that option probably isn't necessary for the scp, but its included here for completeness)

Comment by sud0er 325 weeks and 1 day ago

Yes, ControlMaster no is default indeed. It can be useful in other cases to use auto instead, if you don't care to have a socket always open, but you might have several SSH connections following one another. In that case, you don't need the "ssh -MNf" command, and the first SSH command to be launched will create the socket which will be used by the following commands.

Comment by raphink 325 weeks and 1 day ago

I use:

ssh -MNTf <user>@<host>

Which adds the '-T' option to disable pseudo-tty allocation, which lowers the memory used on the remote machine.

Also note that the -N option is only for protocol 2

Comment by AskApache 165 weeks and 2 days ago

Cool, but when you need to maximize network speed, using a single TCP connection is not the best for file transfer.

Comment by colemar 31 weeks and 1 day ago

Your point of view

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