[avahi] Strange MDNS response from Axis cameras

[Marc Krochmal]

Hi Iván,

It looks like the camera is retuning two IP addresses in the  
response, and Avahi uses the last IP address returned.

Axis had to compromise because the preferred Zeroconf solution is to  
only return the 169.254.x.x address when a DHCP server is not  
configured on the network.  Unfortunately, since there's still many  
poor customers in the world that don't have the benefits of Zeroconf,  
these customers are required to manually type the camera's IP address  
into their web browser, and the only way to know the camera's IP  
address ahead of time is to assign a static IP from the factory in  
the range 192.168.x.x and then record that IP in the user manual.   
This doesn't work when you have two cameras on the network that both  
use the same IP address and it doesn't work if your computer doesn't  
have an IP address in the same 192.168.x.x subnet, which often  
requires users to manually change their computer's IP address first,  
which is a real pain.

The compromise Axis made was to additionally assign a 169.254.x.x  
address to be used for Zeroconf, since Zeroconf devices know that  
169.254.x.x addresses are link-local.  So it sounds like your  
computer doesn't know about this address range.

This is all mentioned in Section 2.6.2 of RFC 3927.

<http://www.ietf.org/rfc/rfc3927.txt>

Also, here's a Q&A that explains how to make this work on various  
OSes including Linux.

<http://developer.apple.com/qa/qa2004/qa1357.html>

Best Regards,

-Marc





On Feb 7, 2006, at 8:10 AM, Iván Sánchez Ortega wrote:

> El Martes, 7 de Febrero de 2006 15:09, Sebastien Estienne escribió:
> [...]
>>> Do you mean, something like "ifconfig eth0:0  
>>> 169.254.whatever.whatever" ?
>>> That doesn't look like a clean solution IMHO... I'd like to be  
>>> able to
>>> get the static IP in a direct way... :-/
>>
>> or using zcip / zeroconf package from debian/ubuntu that does that
>> automatically, but it may not be a clean solution in your use case
>
> That's right: I use a network with static IP, and my goal is to use  
> Avahi to
> know the IPs of the cameras, not to switch the entire network to  
> zeroconf.
>
> [...]
>> I have a mac and i've never seems this behaviour.
>
> Maybe your Mac knows that, when it has a static IP Address, it must  
> not use an
> ad-hoc IP address.
>
>> I think some people on this mailing list have better knowlegde about
>> Mdns to answer your issue, hope you'll get answers from them
>
> I hope so, too :-)
>
> I'll try to summarize the question for them:
>
> If a gadget returns this MDNS response:
>
>         axis-00408cxxxxxx.local: type A, class IN, addr 192.168.2.81
>         axis-00408cxxxxxx.local: type A, class FLUSH, addr  
> 169.254.154.134
>         AXIS 213 - 00408CXXXXXX._http._tcp.local: type SRV, class  
> FLUSH,
> priority 0, weight 0, port 80, target axis-00408cxxxxxx.local
>
> Why does windows' uPnP think the gadget's IP is "192.168.2.81", and  
> why does
> Avahi think the gadget's IP is "169.254.154.134"?
>
>
>
> (I think I might as well read the MDNS specification if I have the  
> time...)
>
> Thanks all,
> -- 
> ----------------------------------
> Iván Sánchez Ortega <i.sanchez at mirame.net>  
> <ivansanchez at escomposlinux.org>
>
> Nine out of every ten daemons prefer FreeBSD. Why should you run  
> them in
> anything else?
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