{ 10 comments… read them below or add one }

1 Robert de Bock August 21, 2008 at 10:54 am

Wow, that is indeed a good trick! Never heard of these configuration variables.

Works on Mac OS X 10.5.4, the only remark;
– I have the options set for no host, so your ~/.ssh/config could just be like this:

ControlMaster auto
ControlPath /tmp/ssh-%r@%h:%p

– The manpage suggests to use the variables with different capitalization. See example above.

Regards and thanks for the great trick, indeed fast!

Robert de Bock.

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2 hilbert00 November 11, 2008 at 7:21 am

I’m concerned about security. Is there any security issue using re-using ssh connections?

thanks

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3 hypatia February 3, 2009 at 12:21 pm

The ONLY draw back I’ve found to this is that because all subsequent SSH requests to the same host share the TCP connection, doing a bulk SCP will slow down the responsiveness of the interactive sessions. It’s not a problem most of the time.

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4 silvere March 15, 2009 at 10:33 am

why doesn’t it works in my cygwin?

The error is:
$ ssh sunjingwei@relay01
ssh_msg_recv: read: header
muxclient: msg_recv

thank u very much.

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5 Tamas Herman April 17, 2009 at 11:30 pm

$ ssh -fNM eta
$ ssh eta ls
mm_receive_fd: no message header
muxserver_accept_control: failed to receive fd 0 from slave
ssh_msg_recv: read: header
muxclient: msg_recv

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6 Dale Schaafsma September 2, 2009 at 1:46 pm

FYI, ssh manpages recommend storing the socket in a private location to prevent other users from using the same socket.
As for the cygwin error, my research so far indicates that this is due to passing around a file descriptor… https://bugzilla.mindrot.org/show_bug.cgi?id=1278

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7 Allayna April 16, 2011 at 3:17 am

You’re the grteesat! JMHO

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8 Wojtek March 6, 2012 at 4:00 pm

Hi,
does it works on windows?
My config file looks like:

Host xxxx.xxxxx.xx
    HostName xxxx.xxxxx.xx
    Port YY
    User xyz
    IdentityFile C:\Users\x\.ssh\id_rsa
    ControlMaster auto
    ControlPath C:\Users\x\.ssh\ssh-%r@%h%p

But i have to enter password every time, when connecting to host :(

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9 Vaughan August 21, 2012 at 7:57 am

This is unreal!

Connections to EC2 instances took ~6 seconds to negotiate a connection.

I’m using Chef-Solo and the multiple stages involved in deploying code such as rsync, scp, remote ssh commands, were being dragged down by this connection.

You have made my day!

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10 Tim Zehta February 18, 2013 at 4:12 pm

I wrote an open source utility to managed background ControlMaster sessions: https://github.com/ClockworkNet/cmc

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