Please ensure that you are using Internet Explorer in Desktop Mode and not the default Metro Mode for Tablets.
Note In Windows 8 Operating System, the Internet Explorer has two modes, Desktop and Metro. In the Metro mode, the ActiveX plugins are restricted. You cannot download NAC Agent in the Metro mode. You must switch to Desktop mode and then launch Internet Explorer to download NAC Agent.
This note is found in the "Cisco NAC Appliance - Clean Access Manager Configuration Guide, Release 4.9(3)" found here:
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...