Re: [shara] draft-thaler-port-restricted-ip-issues-00 - A+P tunneling

[Rémi Després <[e-mail]>]

Le 3 mars 2010 à 20:40, Masataka Ohta a écrit :

> Remi wrote:
> 
>> If A+P packets are locally encapsulated over private-address
>> IPv4 (see point 2 above), this remains possible.
> 
> ICMP with PR-IP just works not because of your point 2, but because
> of identifier and sequence number fields copied from request to reply
> just as source and destination port numbers copied (in reverse order)
> from request to reply.

I don't understand what you believe to be wrong wrong in the full statement, which was:

"... you note that non-port-based protocols, ICMP in particular, can still be used with private addresses between two hosts behind the same NAT, and suggest that this is not possible where A+P is used. If A+P packets are locally encapsulated over private-address IPv4 (see point 2 above), this remains possible."

Indeed, if two hosts in a common domain in which they have have private IPv4 addresses in addition to their port-restricted public addresses, nothing prevents them from using any protocol between them with these private addresses (and ICMP in particular).

Explanation welcome.

RD