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Re: ICMP Security Failures
> From: rja@rja-ss20.cisco.com (Randall Atkinson)
> IMHO, the combination of IP-AH-AH-ULP isn't sensible. It adds no value
> to the IP-AH-ULP combination.
>
How would two hosts communicate via AH, if an intervening router acting as a
firewall is in place to enforce communication with AH? (similar to the scenario
in the photuris draft section C.3)
With IP-AH-ULP the router needs the key used to generate the AH. Otherwise
the intervening router could only check, that there is an AH present, but
could not check if AH is correct. Sharing the key with the router on the
other hand degrades security, because the router can forge the AH of the host.
With IP-AH-AH-ULP the sending host could generate one AH with the key shared with
the router and the other AH with a key shared with the other host.
Uwe
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