All things related to multicast

[John Kristoff <>]

On Tue, 05 Nov 2002 18:08:17 -0800
Tom Pusateri 
<>
 wrote:

> I can't really think of any problems a "rogue querier" can cause.
> All IGMP routers listen to membership reports and time groups out
> independently.
> 
> As long as someone sends queries (which will fall back to any other
> router if the rogue querier doesn't follow the protocol), the routers
> will have the right membership.
> 
> What is the threat or attack you're concerned about?

I thought there might be some potential state related problems for edge
routers if there was a rogue querier, but this as you reminded me, this
is less of problem than I originally thought.

As others pointed out, there is some potential version compatibility
issues.  I'm personally not too concerned about this though.  Using the
lowest IP address as default queurier isn't that big of a deal to me
either, as long as a rogue default querier can't mess up other valid
IGMP routers.

I haven't looked at any code or ran any tests, but I wonder if it is
possible to fool other IGMP routers into thinking that queuries went to
all hosts when they really did not.  This type of problem would be just
an implemenation issue that could be easily fixed.

John