netcat used by VNC uses -q option which is not universally supported

[Mikko Kortelainen]

Binary package hint: virt-manager

After upgrading from Jaunty to Karmic, a remote CentOS 5.4 server with libvirt is unable to display screen using VNC because the nc (netcat) command on CentOS does not support the -q option, and the virt-manager in Karmic tries to use it. Earlier versions of Ubuntu showed the remote desktop fine without the -q option. Requesting removal if possible. The same version of netcat is used on Red Hat and CentOS versions 4 and 5 (at least), and possibly on other distributions as well.

The following error message is displayed by virt-manager in debug mode:

2009-11-04 12:35:01,428 (details:1265): Trying console login
2009-11-04 12:35:01,433 (details:1278): Graphics console configured at vnc://<email address hidden>:5902
2009-11-04 12:35:01,434 (details:1291): Starting connect process for bogus.domain.com 5902
2009-11-04 12:35:01,435 (details:1219): Spawning SSH tunnel to bogus.domain.com, for 127.0.0.1:5902
2009-11-04 12:35:01,440 (details:1242): Tunnel PID 25 FD 9822
nc: invalid option -- q
usage: nc [-46DdhklnrStUuvzC] [-i interval] [-p source_port]
   [-s source_ip_address] [-T ToS] [-w timeout] [-X proxy_version]
   [-x proxy_address[:port]] [hostname] [port[s]]
2009-11-04 12:35:31,818 (details:1250): Shutting down tunnel PID 9822 FD 25
2009-11-04 12:35:31,819 (details:1173): VNC disconnected

This can be fixed by installing a version of nc which recognizes the -q option on the remote server.

[zigi (ziegleka)]

> This can be fixed by installing a version of nc which recognizes the -q option on the remote server.

Could you recommend from which source (repository, distribution)? Thank you

[zigi (ziegleka)]

I can confirm this bug. Karmic and Lucid are affected.

[zigi (ziegleka)]

This can be fixed by editing /usr/share/virt-manager/virtManager/details.py , line 1236:

-- argv += [ server, "nc", "-q", "0", vncaddr, str(vncport) ]
++ argv += [ server, "nc", vncaddr, str(vncport) ]

[Alex Tabisz (alex-tabisz)]

Zigi - nice fix/work around - thanks

[zigi (ziegleka)]

https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/517478

[brainstorm (brainstorm)]

On new virt-manager releases (0.8.3) from dnjl's PPA:

https://launchpad.net/~dnjl/+archive/virtualization

The offending "nc" code has moved to:

/usr/share/virt-manager/virtManager/console.py, line 508

argv += [ server, "nc", "-q", "0", vncaddr, str(vncport) ]

Unfortunately, zigi's fix does not work in that case :-/

[zigi (ziegleka)]

https://bugzilla.redhat.com/show_bug.cgi?id=517778

[zigi (ziegleka)]

From previous bug report on RedHat's bugzilla:

"This is now fixed upstream: we pass a shell script as the SSH command, and try
to detect these incompatibilities. It's definitely a hack, but we don't have a
lot of options:

http://hg.fedorahosted.org/hg/virt-manager/rev/1f781890ea4a "

[Launchpad Janitor (janitor)]

This bug was fixed in the package virt-manager - 0.8.2-2ubuntu4

---------------
virt-manager (0.8.2-2ubuntu4) lucid; urgency=low

  * debian/patches/autodetect-nc-params.patch: autodetect if the remote
    nc command supports the -q option. (LP: #474107)
  * debian/patches/0003-Make-sure-we-quit-afer-EOF-on-stdin.patch: disabled
    as the previous patch replaces it.
 -- Marc Deslauriers <email address hidden> Tue, 02 Mar 2010 14:43:43 -0500

[zigi (ziegleka)]

I can't test if this patch helps, due to same error in libvirtd. With virt-manager - 0.8.2-2ubuntu4 I can't connect to systems which use nc without -q.

[Marc Deslauriers (mdeslaur)]

Just so I can try and reproduce the problem you're having, you're connecting to an up-to-date CentOS 5 server with the default CentOS libvirt packages?

[brainstorm (brainstorm)]

Yes, that was my case (after my workaround on /usr/local/bin/nc):

# rpm -qi libvirt
Name : libvirt Relocations: (not relocatable)
Version : 0.6.3 Vendor: CentOS
Release : 20.1.el5_4 Build Date: Wed 21 Oct
2009 12:51:24 AM CEST
(...)

Regards,
Roman

On Wed, Mar 3, 2010 at 2:10 PM, Marc Deslauriers
<email address hidden> wrote:
> Just so I can try and reproduce the problem you're having, you're
> connecting to an up-to-date CentOS 5 server with the default CentOS
> libvirt packages?
>
> --
> netcat used by VNC uses -q option which is not universally supported
> https://bugs.launchpad.net/bugs/474107
> You received this bug notification because you are a direct subscriber
> of the bug.
>