Re: [Sheflug] igmp packets...... it's getting worse....

["Stephen J. Turnbull" <nospam [at] sk.tsukuba.ac.jp>]

>>>>> "Ross's" == Ross's Mail <ross.h [at] ntlworld.com> writes:

cupsd      470  root    0u  IPv4       1017               TCP *:631 (LISTEN)
cupsd      470  root    2u  IPv4       1018               UDP *:631

Here's the source of the UDP packets you were seeing.

    Ross's> no mention of igmp!

Because there's no socket open on your machine.

The protocol has already been identified as igmp query:

    Ross> 18:28:27.055052 213.105.116.217 > 224.0.0.1: igmp query [ttl 1]

Why you are getting those packets, you'd have to ask NTL.  But IGMP,
like ICMP, is a control protocol.  It may be necessary "just in case"
you want to join a multicast group (eg, it may simply be identifying
the multicast router).  That's just a guess, and not even particularly
well-informed.

In any case, control protocols are messages to the kernel (or network
routing code, which theoretically could be in a server), they are
independent, self contained datagrams, and don't need the socket API.
So they don't have it.  :-)

Go to your nearest IETF mirror and look up multicast and IGMP in the
RFCs if NTL won't tell you what's going on.

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