Re: [Qemu-devel] [PATCH] Remote console access though socket

[Oliver Gerlich]

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Daniel Veillard schrieb:
> On Sat, Mar 11, 2006 at 05:24:40PM +0100, Oliver Gerlich wrote:
> 
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>>Daniel Veillard schrieb:
>>
>>>  Hi,
>>>
>>>enclosed is a first version of a patch to allow remote access and control
>>>for QEmu instances, I'm not suggesting to apply it as is (though it seems
>>>to work in my limited testing) but would rather like to get comments back
>>>for choices I'm facing. 
>>
>>[...]
>>
>>> There is a number of open questions which would need to be resolved before
>>>applying any such patch:
>>>   - First one is the unix socket, we could as easilly start normal port
>>>     based access but:
>>>     + I would really like to be able to list the current running instance
>>>       without checking all process on the OS, and mapping in the file
>>>       system seems the easiest way
>>
>>Just an idea: how about using "Multicast DNS" (see multicastdns.org)?
>>IIUC it provides a generic way to find services on a net; and it's
>>supported at least by MacOSX and with eg. Avahi (see avahi.org) also on
>>Linux. Not sure about Windows, though...
> 
> 
>   It's rather LAN oriented,
Yes, that's a bit ugly.

> I need first to find the ports of the 
> QEmu instances (plural, if you limit to one per box, then you can block the
> default port number and there would be no problem) on a local machine. I
> don't think that "Multicast DNS"/RendezVous works with random port numbers,
> all it does over normal TCP is scan for local hosts without using DNS
> resolution. Again I don't think it's really the problem I'm trying to solve,
> maybe I just didn't expressed myself clearly :-)
> 
> Daniel
> 

After experimenting with the avahi apps a bit, I think mDNS can indeed
advertise several services on the same host with different ports! I ran
"avahi-publish -s -H localhost myserver1 _http._tcp 80" in one terminal,
then "avahi-publish -s -H localhost myserver2 _http._tcp 12345" in
another terminal. This advertised two HTTP servers which were running on
my local host, on ports 80 and 12345, under the names myserver1 and
myserver2.
avahi-discover then displayed these two services, with their names and
the correct port numbers. And in konqueror, browsing to "zeroconf:/"
also showed the two "WWW servers" correctly.

So, this could provide the functionality you were looking for... But it
still has the drawback that zeroconf seems to be quite a big framework,
and it requires multicast DNS in the kernel and such stuff...

Regards,
Oliver
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