The most ideal design would be the Dual DMZ implementation design. Of course you need to have two interfaces on the firewall only for the concentrator - apart from internal, external and any other DMZ you might have.
Some of the benefits of this design woule be: Unauthorized attempts will be intercepted by the firewall and traffic destined for the concentrator will be logged by the firewall and firewall can protect the concentrator from DOS attacks.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...