Jay R. Ashworth
jra at scfn.thpl.lib.fl.us
Wed Dec 24 02:14:29 UTC 1997
On Tue, Dec 23, 1997 at 05:32:15PM -0600, Phil Howard wrote:
> When a packet arrives, take note of the interface and gateway it came from.
> Check the route tables for where a reply to this packet could be delivered.
> Don't choose only the best route, but compare where the packet came from
> with all valid reply routes (except broad defaults larger than a certain
> size that can be configured). If the packet came from where it is valid
> to reply, then allow the packet to proceed. If not, then discard it (an
> ICMP probably won't make it back to the right place anyway).
Oh ghod... weren't you around, Phil, when _I_ got roundly trounced and
reviled as a clueless newbie about 3 months ago for alomst exactly the
The outcome as I recall, was that the only practical thing to do was
ingress filtering at boundary routers, if they would.
Jay R. Ashworth jra at baylink.com
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