Bug 489629 - Connection to VNC server tunneled over ssh refused in some circumstances
Connection to VNC server tunneled over ssh refused in some circumstances
Product: Fedora
Classification: Fedora
Component: kvm (Show other bugs)
All Linux
low Severity medium
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Assigned To: Glauber Costa
Fedora Extras Quality Assurance
Depends On:
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Reported: 2009-03-10 20:38 EDT by Jonathan Underwood
Modified: 2009-03-11 07:59 EDT (History)
7 users (show)

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Doc Type: Bug Fix
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Last Closed: 2009-03-11 07:30:22 EDT
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Description Jonathan Underwood 2009-03-10 20:38:00 EDT
Description of problem:
On a machine, let's call it VirtHost, I start a guest OS instance running under kvm. On VirtHost I can start a VNC viewer (I'll use vinagre throughout) and can connect to my guest OS as expected on port 5900.

Now I move to a different machine (let's call it RemoteHost) and issue the command:

ssh -L 6900:localhost:5900 VirtHost

and now I can run a VNC viewer on RemoteHost connecting to localhost::6900 in order to access the guest running on VirtHost via VNC. All well and good and working as expected.

However, now on VirtHost if I instead have these lines in my .ssh/config file:

Host VirtHost
     LocalForward localhost:6900 VirtHost:5900

and then ssh in to VirtHost I find I cannot connect localhost::6900 in order to connect to the guest OS, and in the ssh session I see:
channel 3: open failed: connect failed: Connection refused

This did work on F-9.

I'm not sure if this is a kvm or libvirt of openssh problem. Reporting against kvm initially.

Version-Release number of selected component (if applicable):
openssh-5.1p1-3.fc10.x86_64 (on both machines)
Comment 1 Daniel Berrange 2009-03-11 07:30:22 EDT
Works just fine for me - I think you have your .ssh/config on the wrong host - it needs to be configured on the host you're ssh'ing from, not to. In any case this isn't a KVM or libvirt bug, since neither care about ssh forwarding.
Comment 2 Jonathan Underwood 2009-03-11 07:59:07 EDT
Yes, sorry, the line in my bug report that read:

"However, now on VirtHost if I instead have these lines in my .ssh/config file:"

should have read:

"However, now on RemoteHost if I instead have these lines in my .ssh/config file:"

I have however tracked down the problem - it's a "feature" of the present version of openssh - it all works as expected if I replace the hostnames in the config file with IPV4 hostnames, otherwise openssh tries IPV6 ones.

Sorry for the noise.

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