IMProxy is an IGMP/MLD Proxy daemon written in c for Linux router.
Features:
It support one upstream and multiple downstream.
You can use VLC Player, or other mcast test tools. I will show you have to test with mcast_test.py in this repository. On downstream side PC, run mulitcast recevier.
mcast_test.py -m 224.8.8.8 -r ## Join 224.8.8.8 and start receive packets
On upstream side PC, run mulitcast sender
mcast_test.py -m 224.8.8.8 -s ## send packet to 224.8.8.8
Check if Recevier start to print time.
Take sample.cfg as sample and run test above.
IMProxy create Virtual Network Devices when it start, every interface have a unique index,you can find this through 'cat /proc/net/ip_mr_vif
/var # cat /proc/net/ip_mr_vif
Interface BytesIn PktsIn BytesOut PktsOut Flags Local Remote
15 wan1 15804 50 0 0 00000 C0A8164C 00000000
24 eth0.1 0 0 15804 50 00000 C0A81501 00000000
26 eth0.3 0 0 0 0 00000 C0A81301 00000000
27 eth0.4 0 0 0 0 00000 C0A81401 00000000
28 eth0.5 0 0 9264 24 00000 C0A81B01 00000000
When IMProxy receive igmp report on downstream interface(eth0.1), improxy will parse it and join related group on upstream interface(wan1)
cat /proc/net/igmp
/var # cat /proc/net/igmp
Idx Device : Count Querier Group Users Timer Reporter
...................
15 wan1 : 9 V3
E0080808 1 0:00000000 0
E00000FB 1 0:00000000 0
E00000FC 1 0:00000000 0
E0000009 1 0:00000000 0
EFFFFFFA 1 0:00000000 0
E0000002 1 0:00000000 0
E0000016 1 0:00000000 0
E0000001 1 0:00000000 0
24 eth0.1 : 7 V3
E0000009 1 0:00000000 0
E0000016 1 0:00000000 0
E0000002 1 0:00000000 0
EFFFFFFA 1 0:00000000 0
E0000001 1 0:00000000 0
.........................
When mulitcast data arrive at upstream interface(wan1), linux kernel send a packet to improxy, this packet contain source address,group address and interface, according to these information,IMProxy will create a Multicast Forwarding Cache,you can find this through cat /proc/net/ip_mr_cache
/var # cat /proc/net/ip_mr_cache
Group Origin Iif Pkts Bytes Wrong Oifs
E0080808 C0A80799 15 8 8480 0 24:1 /*froward data from 15(wan1) to 24(eth0.1) */
EFFFFFFA C0A80799 15 100 31608 0 24:1 28:1
EFFFFFFA C0A80199 65535 -2073669404 4 -2073669404
EFFFFFFA C0A81501 65535 -2073667868 4 -2073667868
Kernel forward multicast data on the basis of multicast forwarding cache.