[Qemu-devel] SSH console for qemu

[Qemu-devel] SSH console for qemu

[Nikita A Menkovich]

Hello,

I'm using qemu with libvirt and I want to create SSH emergency console
to linux/unix guests, same way as it is realized in qemu VNC.
Maybe someone could help me to determine a place to dive in this question.

I think the best way to make it - extend qemu API. But if this could
be made with libvirt - this will be also fine.

-- 
Nikita A Menkovich
http://libc6.org/
JID: menkovich@gmail.com

Re: [Qemu-devel] SSH console for qemu

[Stefan Hajnoczi]

On Wed, Jul 6, 2011 at 3:08 PM, Nikita A Menkovich <menkovich@gmail.com> wrote:
> I'm using qemu with libvirt and I want to create SSH emergency console
> to linux/unix guests, same way as it is realized in qemu VNC.
> Maybe someone could help me to determine a place to dive in this question.
>
> I think the best way to make it - extend qemu API. But if this could
> be made with libvirt - this will be also fine.

Serial console and the "virsh console" command?

Stefan

Re: [Qemu-devel] SSH console for qemu

[Nikita A Menkovich]

Seems no, I think, that the best way is running some kind of ssh
daemon, that connects to console (/dev/vcsa1 for example), that listen
on port and send to output console events on boot, and allow to work
with server with simple ssh client. Also important feature will be
saving history of output.

On 6 July 2011 19:27, Stefan Hajnoczi <stefanha@gmail.com> wrote:
> On Wed, Jul 6, 2011 at 3:08 PM, Nikita A Menkovich <menkovich@gmail.com> wrote:
>> I'm using qemu with libvirt and I want to create SSH emergency console
>> to linux/unix guests, same way as it is realized in qemu VNC.
>> Maybe someone could help me to determine a place to dive in this question.
>>
>> I think the best way to make it - extend qemu API. But if this could
>> be made with libvirt - this will be also fine.
>
> Serial console and the "virsh console" command?
>
> Stefan
>



-- 
Nikita A Menkovich
http://libc6.org/
JID: menkovich@gmail.com
Tel: +7 (921) 423-96-48

Re: [Qemu-devel] [libvirt-users] SSH console for qemu

[Eric Blake]

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On 07/07/2011 02:36 AM, Nikita A Menkovich wrote:
> Seems no, I think, that the best way is running some kind of ssh
> daemon, that connects to console (/dev/vcsa1 for example), that listen
> on port and send to output console events on boot, and allow to work
> with server with simple ssh client. Also important feature will be
> saving history of output.

If you're trying to capture boot events, then you have to have an SGA
(serial graphics adaptor) capable BIOS that can output boot events on
the serial console.  There's recent work underway to add that feature to
qemu, and to expose that feature from libvirt:

https://www.redhat.com/archives/libvir-list/2011-July/msg00174.html

Setting up an ssh daemon in the guest is too late - the daemon won't be
set up until the guest has already booted, so there's no way to have
that daemon forward boot messages back to the host in a timely manner.
I think you're trying too hard - 'virsh console' really is the way to
read all messages output to the guest's console, and your only missing
piece is that you also appear to want BIOS to output to the console.

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] SSH console for qemu

[Stefan Hajnoczi]

On Thu, Jul 7, 2011 at 9:36 AM, Nikita A Menkovich <menkovich@gmail.com> wrote:
> Seems no, I think, that the best way is running some kind of ssh
> daemon, that connects to console (/dev/vcsa1 for example), that listen
> on port and send to output console events on boot, and allow to work
> with server with simple ssh client. Also important feature will be
> saving history of output.

If you configure an ssh daemon properly you can have it invoke "virsh
console <domain>" as the shell.  Remember to lock down port forwarding
and sftp.

Stefan

Re: [Qemu-devel] [libvirt-users] SSH console for qemu

[Nikita A Menkovich]

I want to launch very minimal ssh daemon (that listen on selected port
and allows only input commands and read output from console)  that
launch when guest started, and this not run inside a guest.
Thanks to the link for patch

On 7 July 2011 22:19, Eric Blake <eblake@redhat.com> wrote:
> On 07/07/2011 02:36 AM, Nikita A Menkovich wrote:
>> Seems no, I think, that the best way is running some kind of ssh
>> daemon, that connects to console (/dev/vcsa1 for example), that listen
>> on port and send to output console events on boot, and allow to work
>> with server with simple ssh client. Also important feature will be
>> saving history of output.
>
> If you're trying to capture boot events, then you have to have an SGA
> (serial graphics adaptor) capable BIOS that can output boot events on
> the serial console.  There's recent work underway to add that feature to
> qemu, and to expose that feature from libvirt:
>
> https://www.redhat.com/archives/libvir-list/2011-July/msg00174.html
>
> Setting up an ssh daemon in the guest is too late - the daemon won't be
> set up until the guest has already booted, so there's no way to have
> that daemon forward boot messages back to the host in a timely manner.
> I think you're trying too hard - 'virsh console' really is the way to
> read all messages output to the guest's console, and your only missing
> piece is that you also appear to want BIOS to output to the console.
>
> --
> Eric Blake   eblake@redhat.com    +1-801-349-2682
> Libvirt virtualization library http://libvirt.org
>
>



-- 
Nikita A Menkovich
http://libc6.org/
JID: menkovich@gmail.com
Tel: +7 (921) 423-96-48