Kuhtz, Christian wrote:
... All hairsplitting aside, given that the term NAT these days is mostly used in a PAT (particularly in a customer connecting to the I) context, what isn't secure about?
mangling the header doesn't provide any security, and if you believe it does, do the following exercise: Configure a static NAT entry to map all packets from the public side to a single host on the private side. Show how that mapping provides any more security than what would exist by putting the public address on that host. A stateful filter that is automatically populated by traffic originated from the private side is what is providing 'security'. That function existed in routers long before NAT was specified by the IETF (see RFC1044 for vendor). Tony