Understanding The Network Address Translation Table

The Network Address Translation table. This article explains the NAT table and its functionality within a router,firewall and server. Understand how the NAT table works, the different NAT modes available and how these can be used to provide increased security for your network, but also expose it if used incorrectly.

http://www.firewall.cx/networking-topics/network-address-translation-nat/228-nat-table.html

How to Restrict Cisco IOS Router VPN Client to Layer-4 (TCP, UDP) Services - Applying IP, TCP & UDP Access Lists

Configure and setup your Cisco VPN router to restrict IPSec VPN clients to specific IP addresses, networks, TCP or UDP ports & network services. Learn how to overcome Cisco IOS VPN group access list limitations (TCP/UDP Services) while giving you maximum control, flexibility and granularity over your Cisco IPSec VPN clients and groups.

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/941-cisco-router-vpn-client-acl.html