13

Is there a way to know if the Red Hat Linux Servers on my network have IP Multicasting enabled? The output that I get by running the cat /proc/net/igmp command is the following

Idx Device    : Count Querier   Group    Users Timer    Reporter
1   lo        :     0      V3
                010000E0     1 0:00000000       0
2   eth0      :     3      V3
                010000E0     1 0:00000000       0
  1. Does this mean that IP Multicasting is enabled on my network?
  2. Does this also mean that th server from which I ran the cat command belongs to Group 1?
Swapnonil Mukherjee
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3 Answers3

17

To check if multicast is enabled on the interface do a "ifconfig eth0" and look for: MULTICAST

rkthkr
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6

According to howto

cat /proc/net/igmp

will show the groups you are currently subscribed to

Unreason
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0

These days, iproute2, or rather its ip command will also give you the answer:

$ ip link

(or ip l for short)

will present you with something like this:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 [...]
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp0s31f6: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 [...]
    link/ether ab:cd:ef:12:34:56 brd ff:ff:ff:ff:ff:ff

where you can see that there is no multicast on my loopback device, but yes, my ethernet port does indeed do multicast.

slm
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grandchild
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