Certs, you could use as the other poster mentioned, however a savvy user would be able to export the cert and use it on another PC. You would have to use something like Cisco CleanAccess in conjunction to get some sort of functionality.
The other option is to use AnyConnect SSL VPN client, which would allow you to use CSD (Cisco Secure Desktop) which can check the machine to see if it is corporate machine or not.
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...
[toc:faq]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 and UDP are I...