You can get this information from the appropriate kernel
source file (you just have to know how to read it). In this case, it goes as follows:
First is the index of the interface (padded with spaces on the right so the whole field takes up 4 columns). Second is the name of the interface (space-padded to 15 columns). Next is the number of dmi users (space-padded to 5 columns), followed by the number of dmi gusers (space-padded to 5 columns). Last is a byte-by-byte hexdump of the dmi address.
/proc/net/dev_mcast
