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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?
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3 Answers 3

up vote 11 down vote accepted

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

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ifconfig command is not enabled on the servers on our network. –  Swapnonil Mukherjee May 3 '10 at 9:33
2  
On RedHat-flavour systems normal users don't have /sbin (where ifconfig lives) in their path. If you're on a RedHat-like system and not the root user try running it as /sbin/ifconfig. –  markdrayton May 3 '10 at 10:19
    
Thanks Mark, Running ifconfig from sbin gives me the following output eth0 Link encap:Ethernet HWaddr 00:14:22:1A:AF:DB inet addr:10.1.0.74 Bcast:10.1.7.255 Mask:255.255.248.0 inet6 addr: fe80::214:22ff:fe1a:afdb/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:70747195 errors:0 dropped:0 overruns:0 frame:0 TX packets:6965432 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 I can see MULTICAST in the output. –  Swapnonil Mukherjee May 3 '10 at 10:37
    
Your eth0 interface has multicast enabled :) –  rkthkr May 3 '10 at 10:53
7  
"netstat -g" will give you group membership information. –  rkthkr May 3 '10 at 10:57

According to howto

cat /proc/net/igmp 

will show the groups you are currently subscribed to

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how can I subscribe to other groups or interfaces?? which I got from netstat -g –  jazzz Nov 10 at 20:25

try below link may help

http://www.tldp.org/HOWTO/Multicast-HOWTO.html

http://kbase.redhat.com/faq/docs/DOC-2482

http://kbase.redhat.com/faq/docs/DOC-8706

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2  
The first link is from 1998, and the other two require registration. –  Flimm Jul 19 '13 at 11:02

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