RE: Another NAT Traversal question

["Jayant Shukla" <jshukla@trlokom.com>]

> -----Original Message-----
> From: Francis.Dupont@enst-bretagne.fr [mailto:Francis.Dupont@enst-
> bretagne.fr]
> 
>    I don't think you need to do what you have explained.
> 
> => I need it if I consider the transport layer is independent.
> 

Transport layer is not independent of IP layer. The pseudo-header in
transport layer checksum contains IP header information. 

>    If you want, test the checksum before you authenticate/decrypt the
>    packet.
> 
> => how? the checksum is ciphered.
> 

Checksum of the UDP header! If you check the checksum of the UDP header,
and authenticate the packet, how in the world can you have errors or
wrong checksum in the encapsulated part of the packet (I mean apart from
the wrong IP address)? Please explain!

Regards,
Jayant
www.trlokom.com