[avahi] Strange MDNS response from Axis cameras

Iván Sánchez Ortega i.sanchez at mirame.net
Fri Feb 10 01:54:31 PST 2006


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El Viernes 10 de Febrero de 2006 02:17, Lennart Poettering escribió:
> I wonder if we should add some logic to always prefer real addresses
> over ipv4ll if we recieve both when browsing for them. Would make some
> sense, I guess.

Yes but, as Marc pointed out, all Axis cameras come with the default static IP 
(192.168.0.90 IIRC), and I would expect this behaviour from other embedded 
devices as well.

So, IMHO the algorithm to decide whether to choose the static or the 
link-local address from a pool of addresses should be intelligent enough to:
- - Discard non locally routable addresses.
- - Detect potential IP address conflicts (two or more devices announcing the 
same IP).

I agree with Marc: link-local addresses (169.254.0.0) are preferible than 
static addresses.

But it seems a good idea to me to choose the static IP, only if I can't route 
traffic to 169.254.0.0.

Or, avahi could add the relevant entry to the routing table (if there isn't 
already a way to route traffic to link-local addresses), in order to comply 
with RFC 3927*. This way, after I run avahi-browser (or whatever), I could 
automagically use services on devices with a link-local address.

I think this approach is simpler, but I don't know if it can be easily done, 
or secure enough.


*
route add -net 169.254.0.0 netmask 255.255.0.0 dev eth0 metric 99
route add default dev eth0 metric 99
- -- 
- ----------------------------------
Iván Sánchez Ortega <ivansanchez at escomposlinux.org> <i.sanchez at mirame.net>

"If you haven't got anything nice to say about anybody, come sit next to me."
 - Alice Roosevelt Longworth (1884-1980)
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