Re: Question about IGMP host implementation

Hi Bharat,

The security consideration addresses the processing of a report from a different subnet on the router. My question pertains to the processing of a Query from a different subnet on the host.

Kunal 

-----Original Message-----
From: Bharat Joshi [mailto:[email protected]] 
Sent: Wednesday, October 12, 2011 4:20 AM
To: Kunal Shah; [email protected]
Subject: RE: Question about IGMP host implementation

Hi Kunal,

        I think to keep the security tight, it is better to not respond to queries received from a source address which does not fall on a subnet on that interface. Please note that this should be done only broadcast interfaces. It may not work on point-to-point links.

        If you look at the security consideration in RFC 2236, it is mentioned that for reports, the above check should be done.

Regards,
Bharat
________________________________________
From: [email protected] [[email protected]] On Behalf Of Kunal Shah [[email protected]]
Sent: Wednesday, October 12, 2011 6:08 AM
To: [email protected]
Subject: [magma] Question about IGMP host implementation

Hi all,

Can an IGMPv2 host respond to a general query originated from a subnet other then its own?? RFC 2236 states:

""query received" occurs when the host receives either a valid
     General Membership Query message, or a valid Group-Specific
     Membership Query message.  To be valid, the Query message must be
     at least 8 octets long, and have a correct IGMP checksum.  The
     group address in the IGMP header must either be zero (a General
     Query) or a valid multicast group address (a Group-Specific Query)"

There is no requirement for the source address to be on the same subnet as the host.

Thanks,
Kunal


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