May 2020

This is from CentOS 7.7. It may work with other Linux distros, but I cannot guarantee that.

One way to check the IGMP version being used by an interface is to use the following command:

  cat /proc/net/igmp

Below is a sample output:

Idx     Device    : Count Querier       Group    Users Timer    Reporter
1       lo        :     1      V3
                                010000E0     1 0:00000000               0
2       eth0      :     4      V2
                                61FBDBED     1 0:00000000               1
                                FE7F02EB     3 0:00000000               1
                                120000E0     1 0:00000000               1
                                010000E0     1 0:00000000               0
3       eth1      :     3      V3
                                026400EF     1 0:00000000               0
                                016400EF     1 0:00000000               0
                                010000E0     1 0:00000000               0
4       eth2      :     2      V3
                                FE7F02EB     1 0:00000000               0
                                010000E0     1 0:00000000               0

Here we can see that eth0 is using IGMP V2, while eth1 and eth2 are using IGMP V3.