You can consider access control lists or the IOS Firewall Feature Set (which has 59 IDS signatures in it) if you can only implement security on the serial side. To implement a more full featured, robust IDS (to monitor traffic) or firewall, you really need to look on the LAN side of the router. This really depends upon your risk tolerance and policy.
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...