How To: Getting VPN to work through NAT firewalls
With the rising popularity of telecommuting and the increasing need to protect their electronic assets, companies large and small have been turning to Virtual Private Networking (VPN). The good news is that many savvy IT departments realize that many of their telecommuting employees share their broadband connections with consumer-grade routers. Those folks have made their lives easier by using "NAT friendly" VPN gateways and VPN clients that don't require any changes to home users' router settings in order to successfully set up a VPN tunnel.