[Snort-users] non-standard-protocol : BAD-TRAFFIC IP Proto 103 PIM

doug schmidt douglas.j.schmidt at ...11827...
Thu May 17 14:52:56 EDT 2007

> rule.  I know the protocol in question is a routing-related protocol, but
> does anyone have any views or explanation on the normal use of this protocol
> ?

An example of such would be cisco routers configured for HSRP. Routers
will use multicast to send hello's and talk with members of the group.


On 5/17/07, David Ryan <David.Ryan at ...14057...> wrote:
> Hi all,
> I am seeing loads (like 90% of all events) of these events showing up on one
> of my Snort sensors.  I have looked at the description here -
> http://www.snort.org/pub-bin/sigs.cgi?sid=2189 - and I
> looked at the rule definition and it appears to match simply on the
> existence of IP protocol 103 as distinct from any payload within it.
> I see the traffic coming from two known Cisco routers on the subnet I'm
> monitoring and the traffic is destined for which is the multicast
> address for PIM -
> http://www.networksorcery.com/enp/protocol/pim.htm  I have
> also I have seen it on other sites and subnets on the network I am
> monitoring, so I guess whatever function is causing this traffic to
> originate from the router is used across the organisation.
> In order to make the output from snort a little more readable (and because
> it is matching on the protocol and not the payload) I have disabled this
> rule.  I know the protocol in question is a routing-related protocol, but
> does anyone have any views or explanation on the normal use of this protocol
> ?
> Thanks,
> David
> ===========================================
> David Ryan
> IT Security Engineer, Global IT Security
> Quintiles, Global IT - Infrastructure, QDUB
> david.ryan at ...14057...
> v:  +353-1-819-5186, GMT+0
> m: +353-87-124-9108
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