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Network Security Focus-Linux
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Re: CAN-2004-1137

Subject: Re: CAN-2004-1137
Date: Tue, 04 Jan 2005 12:37:38 -0800
From TCP/IP Illustrated, Volume I, pp. 79:

"Like ICMP, IGMP is considered part of the IP layer. Also like ICMP, IGMP messages are transmitted in IP datagrams."

Basically, it is an IP datagram with a protocol # of 2. The second 32-bit chunk is the 32-bit group address, which is a Class D IP address: 224.0.0.0/4. Block that on INPUT using itpables and you should not see those packets again.

iptables -A INPUT -s 224.0.0.0/4 -j DROP iptables -A INPUT -d 224.0.0.0/4 -j DROP


Charles E. Hill

hilton de meillon wrote:

I have been doing a bit of research - there are numerous instances of
iptables scripts containing rules to block IGMP using iptables - am I
correct in saying that IGMP is on the network layer IP protocol 2 hence all
the iptables rulesets claiming to block igmp are misinformed ?.

Is there a igmptables or any other way of selectively blocking IGMP using
linux ?.

Hilton.



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