smurf, the MCI-developed tracing tools

Dax Kelson dkelson at
Mon Dec 29 04:17:28 UTC 1997

> Adrian wrote:
> > But this way, people can only spoof IPs from their own block, and not
> > random addresses. It would kill smurf attacks, make tracing a tad(?)
> > easier, etc, etc. And as I've mentioned before, not all types of floods
> > are ICMP attacks. If you filter ICMP, then I'll start flooding with
> > spoofed source addresses TCP packets with random sequence numbers and from
> > IPs. What, you're going to ask routers to track all the TCP connections
> > going through them now for validation? Erm, how many CPUs more are we
> > going to need..? :)

Something else that needs to be done is we need DEFAULT anti-spoof filters
on all dialin boxes such as those made by Livingston, Ascend, USR, etc.

When a customer calls in and gets assigned an IP address the box should
automatically apply an anti-spoof filter to that port dropping any
packets with an IP source different than the one assigned.

Of course you need a way to overide that for customers who have networks
routed to them.  The box could the RADIUS "Framed-Route" entry as a hint
to which networks to forward IPs from. 

I've had an RFE in with Livingston for over a year to get that added to

Dax Kelson
Internet Connect, Inc.

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