Windows XP has a nice little feature that allows it to be a VPN server, this is for both the home and pro editions. The setup of this is nice and straightforward:
Firstly, go to start > control panel > network connections. Click on ‘Create a new connection’ in the top left. You will be presented with the new connection wizard.
Click next and chose the ‘Setup an advanced connection’ option at the bottom. Then leave the top option on ‘Accept incoming connections’ and click next again.
You will then be presented with a list box of available devices you can allow to connect to your computer, since we are only concerned with creating a VPN you skip this step, just click next. The next step should be left as it is with the ‘Allow virtual private connections’ option checked.
The next step is where we setup the user credentials that we will allow. You can allow multiple accounts and also create new accounts in this step if neccesary. It is always a good idea to create a new account strictly for VPN access and to give it a very strong password of at least 8 characters with uppercase,lowercase and numbers. Once you have selected the appropriate users click next.
The only options we are really concerned about here are the TCP/IP settings. You can configure these in 3 different ways. You can either allow DHCP to automatically allocate the user an ip address, you can specify what address range they can be given, or you can allow the client to assign their own address. One thing to remember here is that you can only have 1 client connected at one time. My advice is to just leave the setting as DHCP and the client will then be automatically assigned an address upon connection.
Once this is done click ok and click next again, your done! You will notice there is a new connection in your network connections called ‘incoming connections’, you can rename this to whatever you like.
Your done! Well not quite, you will need to forward port 1723 which is the PPTP vpn port, this needs forwarding to the machine you’ve set the VPN on. You may also need to enabled ‘PPTP passthrough’ on your router, although this is usually only required client side. Once the port is forwarded you just need to check your software firewall (if applicable) is going to allow the traffic through on port 1723. Windows firewall usually automatically adds the exception in once you create the VPN which is rather handy.
An external machine should be ready to connect to your vpn now using your public ip address, once connected they will then become a part of your local area network.
