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Re: [Xen-users] ssh in rc.local stalls xenU

on Thu, Dec 15, 2005 at 01:38:29PM -0500, Steve Brueckner 
(steve@xxxxxxxxxxxxxx) wrote:
> I'm using Fedora Core 4.  I need to create an ssh port forwarding tunnel to
> my xen0 domain when my xenU domain starts up, so I added this to the xenU's
> /etc/rc.d/rc.local:
> ssh -v -f -L 5500:localhost:5501 xen0_ip tail -f /dev/null
> This causes my VM to pause for about 3 minutes during boot.  Furthermore,
> the ssh tunnel never gets created.  The ssh command is stalling at
> "Connecting to (xen0_IP) port 22"

It would be useful to see what's happening on the remote (well, local)
server side.  Check sshd's logs, and/or run it manually in debug mode
and watch its output as the connection is being attempted:

    sshd -ddDe
<ctrl>-c to exit when done.

> I have null-passphrase authentication keys working, so I can execute the
> tunnel manually after I log in.  So why won't the tunnel work before I log
> in?
> When I try the same trick on the bare-metal host machine and ssh to a
> different physical machine, it works fine: no 3-minute stall and the ssh
> tunnel is created fine.

A three-minute timeout sounds suspiciously like a network timeout.
rc.local runs _after_ all other rc scripts, so networking should be up
and running.

You might want to ammend your script to check networking status,
_before_ the ssh command is executed:

   ifconfig; route -n; ping localhost

Check also that /etc/hosts has a proper localhost entry.
> So what is it about Xen or my xenU domain that breaks ssh before
> login, but not after login?  And what is it about Xen or my xenU
> domain that breaks ssh before login, while it works fine for a
> physical host?

Logs and debug output would be helpful here.


Karsten M. Self <karsten@xxxxxxxxxxxxx>
XenSource, Inc.
2300 Geng Road #250                                +1 650.798.5900 x259
Palo Alto, CA 94303                                +1 650.493.1579 fax

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