Reference Manual

HOW TO share a VPN connection and an Internet connection.

A VPN Connection is really just a special form of Dial-Up Networking connection and NAT32 can share that connection in the usual way. Simply establish the VPN Connection to your VPN Server and then configure NAT32 to use that connection as an Internet Interface. Be sure you configure the MTU of the connection correctly in the appropriate Interface Configuration dialog box. The correct value to use for PPTP-based VPN connections is 1454 bytes, but a value of 1400 bytes may be required in some cases.

The following changes to the Windows TCP/IP configuration on your machine take place when a VPN Connection is established:

• Your machine is given an IP address on the network of the VPN Server.
• Your machine is given a Default Gateway on the network of the VPN Server, but only if you check the Use default gateway on remote network checkbox in the Properties of the connection.
• Any previous Default Gateway on your machine is given a higher metric, which effectively stops Windows from using it. The gateway on the network of the VPN Server is used instead.
• The metric of the Network Route on private LAN adapters is also increased, thus making your private machines unreachable. This problem was corrected in Windows 2000 and later versions of the operating system.

Note that the above changes do not necessarily have any impact on NAT32, as NAT32 bypasses the Microsoft TCP/IP stack for all traffic it forwards to the Internet or to private machines. NAT32 can therefore continue to use the old default gateway if desired, and it can also reach all your private machines exactly as before.

If you want NAT32 to send only traffic addressed to the network of your VPN via the VPN connection, and all other traffic via your DSL or Cable Modem connection, proceed as follows:

Configure the VPN connection to not use the default gateway on the remote network.

Add this line to file user.txt: setis 0

NAT32 will then send all Internet traffic except traffic to your VPN via the default route of your Internet connection. All traffic for addresses on your VPN will be sent via the VPN connection.

SEE ALSO

MTU, VPN Connections, VPN Clients, VPN Servers