Avahi and the loopback interface

[ZioPRoTo (Saverio Proto)]

Hello,

I'm the author of the OLSR mDNS plugin. (http://www.olsr.org).

Please look here for details about the mDNS plugin:
http://zioproto.ninux.org/wordpress/2009/04/04/olsrd-mdns-plugin/

When I was testing my software I tried to configure the plugin to
decapsulate the mDNS traffic to the loopback interface, so that the
router itself is able to see mDNS traffic.

However it seems that avahi does not work by default with the loopback
interface, so I tried to following patch:

http://avahi.org/attachment/ticket/198/avahi-core.patch

Now if I launch the avahi-discover I see also the loopback interface
listed, but I don't see the services announced by other machines in
the network. With tcpdump I can see that my application is sending
mDNS messages on the loopback interface, so I was expecting them in
the list when launching avahi-discover.

If I have an application sending mDNS packets to the loopback
interface, are this packets going to be processed by Avahi using the
patch?
There is any other patch I can try ??

Saverio
_______________________________________________
avahi mailing list
avahi@...
http://lists.freedesktop.org/mailman/listinfo/avahi

[Lennart Poettering-8]

On Thu, 04.06.09 15:09, ZioPRoTo (Saverio Proto) (zioproto@...) wrote:

> Hello,
>
> I'm the author of the OLSR mDNS plugin. (http://www.olsr.org).
>
> Please look here for details about the mDNS plugin:
> http://zioproto.ninux.org/wordpress/2009/04/04/olsrd-mdns-plugin/
>
> When I was testing my software I tried to configure the plugin to
> decapsulate the mDNS traffic to the loopback interface, so that the
> router itself is able to see mDNS traffic.
>
> However it seems that avahi does not work by default with the loopback
> interface, so I tried to following patch:
>
> http://avahi.org/attachment/ticket/198/avahi-core.patch
>
> Now if I launch the avahi-discover I see also the loopback interface
> listed, but I don't see the services announced by other machines in
> the network. With tcpdump I can see that my application is sending
> mDNS messages on the loopback interface, so I was expecting them in
> the list when launching avahi-discover.
>
> If I have an application sending mDNS packets to the loopback
> interface, are this packets going to be processed by Avahi using the
> patch?
> There is any other patch I can try ??

Not to my knowledge.

mDNS on the loopback is a messy thing actually, since enabling it by
default might cause services to show up multiple times for normal
applications. Also, multicast support on loopback interfaces is
supported differently on different systems, so we should probably
shortcut packet delivery and bypass the stack for it.

In other words: what you want to do doesn't work and is unlikely to
work ever with Avahi.

Lennart

--
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4
_______________________________________________
avahi mailing list
avahi@...
http://lists.freedesktop.org/mailman/listinfo/avahi