Subject: [NAT] a basic question

From: "Shahrier, Sharif M." <[email-masked]>
Date: Thu, 10 May 2001 12:09:48 -0400

I have a basis question on NAT, and would be grateful of a response.

Suppose a host on private network A wants to send to a host on private
network B. 
For the outgoing datagram, the NAT replaces local s-addr with its public
p-addr. It makes an entry in its table.
The packet is sent to NAT-B to its public address.
When the packet reaches NAT-B, I assumed that NAT-B would have to do a
look-up to replace the public dest-addr
in the packet header, with the private address of the local host to which
the datagram was destinted. 
There is no way to know what the mapping is, unless a mapping entry was
established by some other means beforehand.
In that case, several hosts may have been pre-mapped to the same public
address.
Thus, the NAT-B will not know unambiguously to which host to forward the
datagram to.
Security, problems......

I am sure that thi issue has been solved, and thus would be grateful if
someone can send me a response.

Thanks.

-Sharif.

_______________________________________________
nat mailing list
[email-masked]
http://www.ietf.org/mailman/listinfo/nat