Comments on: SSH Connection Sharing, C++ Visibility, Share Libraries, and GCC Attributes. OH MY!

By: Allan

Allan — Tue, 10 Jul 2007 18:18:45 +0000

Spoke too soon. A bit more digging came up with a definitive “impossible to fix”.

https://bugzilla.mindrot.org/show_bug.cgi?id=1278

Damien Miller:

OpenSSH can’t do anything to resolve this, it is a limitation of the
Cygwin platform libraries. If Cygwin is able to make fd passing work on
Windows, then OpenSSH will automatically work.

I’ll close this bug, because there is nothing we can do here.

By: Allan

Allan — Tue, 10 Jul 2007 18:05:13 +0000

I confirm the Cygwin problem. I’m seeing the same mm_receive_fd under Cygwin running OpenSSH 4.6p1 on the control master session.

On the slave session, the ssh attempt instantly spits out:

ssh_msg_recv: read: header
control_client: msg_recv

I see no resolutions for this on google pertaining to any of these messages or primary fragments.

By: marvin

marvin — Mon, 29 Jan 2007 15:51:38 +0000

On windows (using cygwin ssh) a ‘:’ is not legal in a path name. So using this might be better:
ControlPath ~/.ssh/master-%r@%h-%p (e.g. replace the ‘:’ with a ‘-‘ or something. It probably doesn’t matter unless you are setting ports to something different than 22)

But, BTW, I can’t seem to get this to work on cygwin with SSH 4_5 — it is failing with the master connection saying mm_receive_fd: no message header and closing. Nothing evident on debug — heading to forums now.

By: Steve Friedl

Steve Friedl — Wed, 09 Nov 2005 14:53:06 +0000

I found your link from Jeremy Z’s weblog, and see the you mentioned GNU __attributes__; I’ve covered them pretty well in a Tech Tip that might help make it easier to understand.

Using GNU C __attribute__
http://www.unixwiz.net/techtips/gnu-c-attributes.html

But this SSH connection sharing looks like great poor-man’s VPN – thanks for posting.

~~ Steve

By: ( theflow.de ) » » SSH Connection Sharing

( theflow.de ) » » SSH Connection Sharing — Wed, 09 Nov 2005 12:16:26 +0000

[…] Jay R. Wren – lazy dawg evarlast » SSH Connection Sharing (via) – sehr praktisch […]

By: Sam Morris

Sam Morris — Sun, 06 Nov 2005 16:13:15 +0000

You can have ssh automatically set up a master socket for every connection, with the following in your ssh config file:

host *
ControlMaster auto
ControlPath ~/.ssh/master-%r@%h:%p

For extra security, change ‘auto’ to ‘autoask’ and you will be prompted to confirm when additional connections are accepted.

By: Sean Neakums

Sean Neakums — Sun, 06 Nov 2005 15:09:33 +0000

This is a really nifty feature!

Following advice from the man page, I’m using “ControlPath ~/.ssh_control_%r@%h:%p”, since I log into the same host with different usernames. I’ve added this to the “Host *” section in my ~/.ssh/config, and for each host I want to use it on I add “ConnectionMaster auto” to the relevant host section, so it all Just Works.

By: Joachim Nilsson

Joachim Nilsson — Sun, 06 Nov 2005 14:06:28 +0000

Thanks man, really enlightning read and helpful pointers!

By: Kattni

Kattni — Sat, 05 Nov 2005 20:24:49 +0000

>man jaywren

If only, because then I might have a chance of following half the things you talk about.