Blocking spoofing at the source (was: ICMP Attacks??)

Joe Rhett jrhett at ISite.Net
Fri Aug 22 21:34:07 UTC 1997

> Given the predominance of Ascend in the marketplace, and their general
> configuration style, it would be cool to see an option
> "AllowIpSpoofing=Yes/No" or the like. The boxes already carry routes
> associated with each interface. If a packet arrives that doesn't have a
> route to get it back to the interface it came from, it would be dropped.
> Sure, this may not always be what you want, but in 99% of the cases it
> would be. Implementation via Radius would permit this to be removed from
> people you wish to allow to spoof. :)
This won't work on anything with multiple diverse paths. And I don't know
many companies with their own WANs that don't have such.

So, yes, the idea is nice but the logic would have to be much more
comprehensive than that. And I honestly don't know how you could safely do
it, that won't break half the routing topologies out there.

(if you assume multipath OSPF for the IGP... maybe. But that's one hell of
an assumption.)

Joe Rhett                                                 Systems Engineer
JRhett at ISite.Net                                          ISite Services

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