Hi there!
I have some troubles getting communication between host and container right. My goal is to route the multicast traffic which is arriving from “outside” to the host to the lxd container (my jellyfin container) and vice versa.
I can see that udp packages are arriving on en0:
sudo tcpdump -i eno0 -n “dst host 239.255.255.250 and udp port 1900” -vv
tcpdump: listening on eno0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
14:38:32.841074 IP (tos 0x0, ttl 3, id 0, offset 0, flags [DF], proto UDP (17), length 309)
192.168.13.120.37248 > 239.255.255.250.1900: [udp sum ok] UDP, length 281
14:38:33.071732 IP (tos 0x0, ttl 3, id 0, offset 0, flags [DF], proto UDP (17), length 318)
192.168.13.120.37248 > 239.255.255.250.1900: [udp sum ok] UDP, length 290
14:38:33.289374 IP (tos 0x0, ttl 3, id 0, offset 0, flags [DF], proto UDP (17), length 365)
192.168.13.120.37248 > 239.255.255.250.1900: [udp sum ok] UDP, length 337
14:38:33.406800 IP (tos 0x0, ttl 3, id 0, offset 0, flags [DF], proto UDP (17), length 363)
192.168.13.120.37290 > 239.255.255.250.1900: [udp sum ok] UDP, length 335
14:38:33.406801 IP (tos 0x0, ttl 3, id 0, offset 0, flags [DF], proto UDP (17), length 375)
192.168.13.120.50157 > 239.255.255.250.1900: [udp sum ok] UDP, length 347
192.168.13.120 is a dlna device within my IoT vlan network which I routed to the server which is the container I am talking.
Unfortunately I can send within the jellyfin container packages to 239.255.255.250.1900 and I can see them in the container itself and also on lxdbr0 but not on eno0:
sudo tcpdump -i lxdbr0 -n “dst host 239.255.255.250 and udp port 1900” -vv
tcpdump: listening on lxdbr0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
14:50:31.668979 IP (tos 0x0, ttl 4, id 43961, offset 0, flags [DF], proto UDP (17), length 168)
10.128.122.231.59798 > 239.255.255.250.1900: [bad udp cksum 0x7607 → 0x553d!] UDP, length 140
14:50:31.768811 IP (tos 0x0, ttl 4, id 43966, offset 0, flags [DF], proto UDP (17), length 168)
10.128.122.231.59798 > 239.255.255.250.1900: [bad udp cksum 0x7607 → 0x553d!] UDP, length 140
14:50:31.869643 IP (tos 0x0, ttl 4, id 43970, offset 0, flags [DF], proto UDP (17), length 168)
10.128.122.231.59798 > 239.255.255.250.1900: [bad udp cksum 0x7607 → 0x553d!] UDP, length 140
I conclude that the problem is the traffic between lxdbr0 and eno0 where eno0 gets the multicast packages from outside but does not forward and lxdbr0 gets the packages from the container but does not forward them to eno0 and hence sending them to the router.
Any hints how i can solve this?
Thanks Benjamin!
See also the discussion on openwrt forum:
and