address spoofing

Fri Apr 23 23:30:20 UTC 1999

> > Furthermore, whether the RFC [1918] says so or not, I'm going to block
> > these packets at *my* border routers, because:
> 
> Curious as to the cost (added latency) in doing RFC 1918 source address
> filtering on all packets in the context of cost-benfit analysis.

Well, we added filtering of spoofed source addresses (ie. our own) at our
border routers quite a while ago. Adding filters for the RFC 1918 source
addresses was a complete no-brainer - three more lines in a filter that
already had around 15 lines. *No* visible (to us) increased processor
load or latency.

(I'm sure it can be measured - but in our case it's completely lost in
the noise.)

Steinar Haug, Nethelp consulting, sthaug at nethelp.no