remotely executed netcat (nc) uses -q option which is not universally supported

virsh;
$ virsh -c qemu+ssh://<email address hidden>/system
error: server closed connection
error: failed to connect to the hypervisor

virt-manager:
Unable to open connection to hypervisor URI 'qemu+ssh://<email address hidden>/system':
server closed connection
Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/connection.py", line 896, in _try_open
    None], flags)
  File "/usr/lib/python2.6/dist-packages/libvirt.py", line 111, in openAuth
    if ret is None:raise libvirtError('virConnectOpenAuth() failed')
libvirtError: server closed connection

Maybe you need to install ssh-askpass in order to authenticate.

https://bugs.launchpad.net/ubuntu/+source/virt-manager/+bug/474107

You can fix it temporarily by installing a version of nc which recognizes the -q option on the remote server. You can try my workaround.

On ubuntu system:
# apt-get install build-essential quilt

$ cd /usr/src
$ apt-get source netcat-openbsd
$ cd ./netcat-openbsd-1.89
$ ./debian/rules

Now you have in current directory patched version which you download on the remote server and there compile it.

Bug report for CentOS: http://bugs.centos.org/view.php?id=4188

Bug report for RedHat: https://bugzilla.redhat.com/show_bug.cgi?id=562176

Can't connect from RedHat based systems: https://bugzilla.redhat.com/show_bug.cgi?id=517778

Same here (Client: Ubuntu 9.10, libvirt server: CentOS 5.4). The patch in Bug #474107 fixes it for me.

Bug #474107 does not fix it for me since libvirt itself (virsh) is using -q anyway on new releases:

LIBVIRT_DEBUG=1 virsh -c qemu+ssh://root@xxxx/system

It seems that "nc -q" code is present on libvirt itself too:

13:55:49.688: debug : doRemoteOpen:564 : proceeding with name = qemu:///system
13:55:49.688: debug : virExecWithHook:640 : ssh -l root xxxx nc -q 0 -U /var/run/libvirt/libvirt-sock
13:55:49.701: debug : remoteIO:8431 : Do proc=66 serial=0 length=28 wait=(nil)
13:55:49.702: debug : remoteIO:8493 : We have the buck 66 0xb76f8008 0xb76f8008
13:55:50.049: debug : remoteIOEventLoop:8378 : Giving up the buck due to I/O error 66 0xb76f8008 (nil)
13:55:50.049: debug : do_open:1126 : driver 4 remote returned ERROR

Putting a nc binary that supports "-q" flag under /usr/local/bin fixes it for me, see (as zigi wrote):

http://bugs.centos.org/view.php?id=4188

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

Libvirt should use similar hack like in virt-manager (from previous RedHat's bugzilla report):

"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 "

I've built updated libvirt packages in my testing PPA that should fix this:

https://launchpad.net/~mdeslaur/+archive/testing

Please test them and indicate here if they solve the issue for you.

Thanks

@Marc Deslauriers:

Nice work, your version works just fine. Please upload your patch to upstream.

Marc, can you give me advice, how to start with patching/bug fixing, making own packages and building own PPA repository, thank you.

@zigi:

Thanks for testing, I'll upload it today.

off topic: This link has the info you are looking for: https://wiki.ubuntu.com/UbuntuDevelopment

This bug was fixed in the package libvirt - 0.7.5-5ubuntu10

---------------
libvirt (0.7.5-5ubuntu10) lucid; urgency=low

  * debian/patches/9015-autodetect-nc-params.patch: autodetect if the
    remote nc command supports the -q option. (LP: #517478)
  * debian/patches/0006-Terminate-nc-on-EOF.patch: disabled
    as the previous patch replaces it.
 -- Marc Deslauriers <email address hidden> Thu, 04 Mar 2010 07:58:52 -0500

@Marc Deslauriers

Hi this is Raghav I have installed 10.04 Lucid beta 2 Desktop and also have ssh askpass;

I have virt-manager version 0.8.2;

I have made the changes to console.py and invoke virt-manager; i still face the problem
Unable to open connection to hypervisor URI qemu+ssh://root@10.18.14.186/system
cannot recv data : connection reset by peer

May beyou need to install ssh askpass; Could you pls let me know how to fix this issue

@Raghav

After virt-manager (0.8.2-2ubuntu4) and libvirt (0.7.5-5ubuntu10) were released you don't have to patch virt-manager.

Actually I don't use ssh keys with password for virt-manager (no X ssh-askpass installed) and I have installed these packages:

libvirt-bin 0.7.5-5ubuntu27
libvirt0 0.7.5-5ubuntu27
libvirt0-dbg 0.7.5-5ubuntu27
python-libvirt 0.7.5-5ubuntu27
virt-manager 0.8.2-2ubuntu8

I can normaly manage remote systems via virt-manager and virsh.

@Zigi
MAny thanks for the support
it resolved the issue
Raghav

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----- Original Message -----
From: zigi <email address hidden>
Date: Sunday, April 25, 2010 12:46 pm
Subject: [Bug 517478] Re: remotely executed netcat (nc) uses -q option which is not universally supported
To: <email address hidden>

> @Raghav
>
> After virt-manager (0.8.2-2ubuntu4) and libvirt (0.7.5-5ubuntu10) were
> released you don't have to patch virt-manager.
>
> Actually I don't use ssh keys with password for virt-manager (no X
> ssh-
> askpass installed) and I have installed these packages:
>
> libvirt-bin 0.7.5-5ubuntu27
> libvirt0 0.7.5-5ubuntu27
> libvirt0-dbg 0.7.5-5ubuntu27
> python-libvirt 0.7.5-5ubuntu27
> virt-manager 0.8.2-2ubuntu8
>
> I can normaly manage remote systems via virt-manager and virsh.
>
> --
> remotely executed netcat (nc) uses -q option which is not
> universally supported
> https://bugs.launchpad.net/bugs/517478
> You received this bug notification because you are a direct subscriber
> of the bug.
>
> Status in libvirt virtualization API: Unknown
> Status in “libvirt” package in Ubuntu: Fix Released
> Status in “libvirt” package in CentOS: Unknown
> Status in “libvirt” package in Fedora: Unknown
> Status in “virt-manager” package in Fedora: Unknown
>
> Bug description:
> I Can't connect to none-debian based distros with remote tunel
> over SSH (qemu+ssh) - virsh / virt-manager.
>
> LIBVIRT_DEBUG=1 virsh -c qemu+ssh://<email address hidden>/system:
> ...
> debug : virExecWithHook:620 : ssh -l root xxx.xxx.xxx.xxx nc -q 0 -
> U /var/run/libvirt/libvirt-sock
> ...
>
> As you can see nc is executed with -q option. This option isn't
> universally supported (at least in CentOS, Fedora, RedHat,
> OpenSuse), it's debian patch.
>
> My system is (K)Ubuntu 10.04 Lucid:
> libvirt - 0.7.5-5ubuntu5
> netcat-openbsd - 1.89-3ubuntu1
> virt-manager - 0.8.2-2ubuntu1
>
> Patches which cause this problem:
> libvirt : 0006-Terminate-nc-on-EOF.patch
> virt-manager : 0003-Make-sure-we-quit-afer-EOF-on-stdin.patch
>
> Solutions:
> Disable these patches until the nc patch "quit-timer.patch" will
> be accepted by upstream or distributed into other main distributions.
>
> To unsubscribe from this bug, go to:
> https://bugs.launchpad.net/libvirt/+bug/517478/+subscribe
>

Sorry but this "fix" breaks ssh-connections for everyone not using a sh-based shell as login-shell.

I personally use tcsh as login shell and "nc -q 2>&1 | grep -q 'requires an argument';if [ $? -eq 0 ] ; then CMD='-q 0';else CMD='';fi;" isn't valid csh line.

@glance: please open a new bug for that. Thanks.