openssh connection multiplexing with cygwin

Brian Dessent brian@dessent.net
Thu Oct 20 23:44:00 GMT 2005


I've been trying to get the connection multiplexing feature of openssh
to work with Cygwin without success.

I set "ControlPath /tmp/ssh_%h_%r" in ~/.ssh/config.  Then I do

$ ssh -M -N -vvv host

which works fine, and there is a socket in /tmp:

$ ls -l /tmp/ssh*
srw-------  1 brian None 53 Oct 20 16:30 /tmp/ssh_host_brian=

Then in another window I try:

$ ssh -vvv host
OpenSSH_4.2p1, OpenSSL 0.9.8a 11 Oct 2005
debug1: Reading configuration data /home/brian/.ssh/config
debug1: Applying options for *
debug1: Applying options for host
debug1: Reading configuration data /etc/ssh_config
debug1: Applying options for *
debug3: ssh_msg_send: type 1
debug3: ssh_msg_recv entering
debug3: ssh_msg_send: type 1
mm_send_fd: sendmsg(2): Software caused connection abort

The first ssh (master) has now died, with the following messages being
printed after the above command was executed:

debug1: fd 5 clearing O_NONBLOCK
debug3: ssh_msg_recv entering
debug3: ssh_msg_send: type 1
debug3: ssh_msg_recv entering
debug3: client_process_control: receiving 0 env vars
debug2: client_process_control: accepted tty 1, subsys 0, cmd 
mm_receive_fd: no fd

Is this a limitation of Cygwin's unix socket emulation, openssh bug, or
something else?  Below is some information about the installed versions:

The local ssh is the packaged 4.2p1-1:
$ ssh -v 
OpenSSH_4.2p1, OpenSSL 0.9.8a 11 Oct 2005

The remote ssh is:
$ ssh -v       
OpenSSH_4.2p1 Debian-5, OpenSSL 0.9.8 05 Jul 2005

I am running cygwin1.dll and cygserver.exe from CVS as of an hour ago:

$ uname -a
CYGWIN_NT-5.1 booch 1.5.19(0.141/4/2) 2005-10-20 16:11 i686 unknown
unknown Cygwin

$ cygserver -v
cygserver: (cygwin) 1.12
API version 1.5.19(0.141/4/1)-(3.0.0.2) 2005-10-20 16:11
Copyright 2001, 2002, 2003, 2004, 2005 Red Hat, Inc.
Compiled on Oct 20 2005
Default configuration file is /usr/local/etc/cygserver.conf

Brian

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