Computer isn't advertized nor seeing other machines

[nalimilan]

Avahi doesn't seem to work at all on my Ubuntu 10.04 laptop, with version 0.6.25. Other machines (with the very same version) see each other, but don't see my laptop, and from the laptop I can't see other machines. Note I can ping them using their IP addresses, and e.g. login using SSH into them.

I'm always getting:

$ LC_ALL=C avahi-browse -av
Server version: avahi 0.6.25; Host name: milan.local
E Ifce Prot Name                                          Type                 Domain
+ eth1 IPv4 milan [00:12:f0:0c:82:a8]                     Workstation          local
: Cache exhausted
: All for now

While the server seems to be happy:

$ sudo avahi-daemon --debug
Found user 'avahi' (UID 109) and group 'avahi' (GID 120).
Successfully dropped root privileges.
avahi-daemon 0.6.25 starting up.
Successfully called chroot().
Successfully dropped remaining capabilities.
No service file found in /etc/avahi/services.
Joining mDNS multicast group on interface eth1.IPv4 with address 192.168.88.51.
New relevant interface eth1.IPv4 for mDNS.
Network interface enumeration completed.
Registering new address record for fe80::212:f0ff:fe0c:82a8 on eth1.*.
Registering new address record for 192.168.88.51 on eth1.IPv4.
Registering HINFO record with values 'I686'/'LINUX'.
Server startup complete. Host name is milan.local. Local service cookie is 2390332076.
[Nothing more for minutes.]

So I've tried checking that port 5353 is open:

$ sudo iptables -A INPUT -p udp --dport 5353 -d 224.0.0.251 -j ACCEPT
$ sudo iptables -A OUTPUT -p udp --dport 5353 -d 224.0.0.251 -j ACCEPT
$ sudo iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     udp  --  anywhere             224.0.0.251         udp dpt:mdns 

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     udp  --  anywhere             224.0.0.251         udp dpt:mdns 

$ sudo nmap 192.168.88.51 -pU:5353 -sU

Starting Nmap 5.00 ( http://nmap.org ) at 2010-08-29 17:45 CEST
Interesting ports on 192.168.88.51:
PORT     STATE         SERVICE
5353/udp open|filtered zeroconf

Nmap done: 1 IP address (1 host up) scanned in 2.17 seconds

$ LC_ALL=C avahi-browse -av
Server version: avahi 0.6.25; Host name: milan.local
E Ifce Prot Name                                          Type                 Domain
+ eth1 IPv4 milan [00:12:f0:0c:82:a8]                     Workstation          local
: Cache exhausted
: All for now

Here's the configuration of my interfaces (set up using NetworkManager? 0.8). I'm connected using eth1, a wireless connexion with this card (ipw2200 driver): Intel Corporation PRO/Wireless 2200BG [Calexico2]

$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0f:b0:57:55:04  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          Packets reçus:0 erreurs:0 :0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:1000 
          Octets reçus:0 (0.0 B) Octets transmis:0 (0.0 B)
          Interruption:16 

eth1      Link encap:Ethernet  HWaddr 00:12:f0:0c:82:a8  
          inet adr:192.168.88.51  Bcast:192.168.88.255  Masque:255.255.255.0
          adr inet6: fe80::212:f0ff:fe0c:82a8/64 Scope:Lien
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Packets reçus:12906 erreurs:0 :0 overruns:0 frame:0
          TX packets:9416 errors:0 dropped:4 overruns:0 carrier:0
          collisions:0 lg file transmission:1000 
          Octets reçus:10167588 (10.1 MB) Octets transmis:1033254 (1.0 MB)
          Interruption:22 Adresse de base:0xa000 Mémoire:b8006000-b8006fff 

lo        Link encap:Boucle locale  
          inet adr:127.0.0.1  Masque:255.0.0.0
          adr inet6: ::1/128 Scope:Hôte
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          Packets reçus:137 erreurs:0 :0 overruns:0 frame:0
          TX packets:137 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:0 
          Octets reçus:10876 (10.8 KB) Octets transmis:10876 (10.8 KB)

So, in the end, I used Wireshark to monitor traffic on UDP port 5353. Result: no incoming traffic; outgoing packets only from 192.168.88.51 to 224.0.0.251. See attached avahi-wireshark log, which represents all the packets on UDP port 5353 when I start avahi-daemon and I run avahi-browse.

I'm not very familiar with how Avahi works, so please ask for any other information you need.

[nalimilan]

Wireshark log of packets on UDP port 5353 when running avahi-daemon and avahi-browse

[nalimilan]

Hmm, it may sound silly, but I guess I've found an explanation: it seems that when I'm close to my WiFi? access point, or when I'm using an Ethernet connexion, Avahi works. When my wireless connexion has a low quality because I'm away of my router, it doesn't.

This may seem very logical, but it's actually weird because, as I said in the report, I can browse the Web, SSH into other machines and everything you may expect without any trouble. Connexion is very stable. So is it possible that multicast packets send by Avahi are lost by the WiFi? card when other packets aren't? How can I check this? Can it be a bug in the driver?

[lennart]

Sounds like a router problem. Avahi certainly doesn't do anything special based on distance from the router.