WinXP Routing – My consulting services business is heavily dependent on Internet access. Without it, I am pretty much dead in the water.
Since I cannot afford an enterprise satellite backup link, I came up with a more economical way of keeping my network online in the event of a critical infrastructure failure. We experienced such a failure on October 24th, 2005 courtesy of Category 3 Hurricane Wilma.
Verizon, and other carriers, offer wireless (digital / analog) access pretty much anywhere in the US. Download rates for this type of “mobile” Internet access can burst up to 2Mb/sec but typically float around 768Kbps. This is still a respectable speed if you find yourself without a working wired Internet connection.
It’s one thing to have a laptop with wireless Internet access anywhere, anytime, but quite another to have that same access for your entire home / small business. However, it can be done, and this is exactly how I stayed connected during Hurricane Wilma.
How To Configure A Laptop As A Wireless Internet Access Point
Note: I am making the assumption that you already have a basic understanding of IP routing as well as how to use the Windows registry editor. You will also need to install and configure a proxy package, such as winproxy (I actually used an older version that performs Network Address Translation using the VZAccess Valid Internet IP assigned by Verizon as the hiding address). This allows the computers on your internal network to access the Internet. Optionally, you could install Windows 2000 Prof / Server which can perform Internet connection sharing.
I have a relatively new HP/Compaq laptop running Windows XP SP2. I ordered the VZAccess card (aprox $149) and the monthly services (aprox $59.99) from Verizon . The VZAccess card installs in the PCMCIA slot and the laptop already has an integrated 10/100/1000 Ethernet controller. This effectively gives me two Ethernet cards. All routing devices, in this case my laptop, must have at least two Ethernet cards to route between networks, in this case, my home office network and the Internet.
The internal network card, the real Ethernet port integrated into my laptop, was assigned an address such as 192.168.0.254/24 (to be my default gateway for all my internal computers) and the VZAccess card is dynamically assigned an IP address from the carrier.
The real trick is what needs to be done to make WinXP Prof act as a router. In order to do this, you must make a registry change. For those of you with little experience in making registry changes, I must tell you that if you make a serious mistake, you run the chance of really messing your system up. There are Proxy packages that can take care of this for you, and do not require this routing change.
Configuring Windows XP Professional To Route IP
In order to make Windows XP Prof performing IP routing between network segments, you need to perform some changes to the Windows Registry.
At the Start -> Run command, type regedit and press enter. “HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesTcpip Then navigate to the following Parameters”. Selected the “IPEnableRouter” entry, which by default will have the value 0, and change it to 1. Close the registry editor, and reboot your system.
When the system reboots, it will be able to route traffic between your internal network and the Internet (Your Wireless card). Of course, you need to adjust your DNS information to point to an appropriate Domain Name Server on the Internet. All of your internal workstations / systems must point to the internal network card / IP on the laptop as the default gateway.
Conclusion
This seems like a pretty easy setup, and it can be if you have a good understanding of routing and network address translation. The goal of this article was to demonstrate that you can configure a pretty inexpensive solution that can keep you connected in the event of a communications / power failure. Of course, there are other things to consider, for instance, we were without power for 7 days, however, we had a gas generator that kept us going. The bottom line is, where there is a will, there is a way. And the way for me was the Poor Man’s Wireless Internet!
Darren Miller is an Information Security Consultant with
over sixteen years experience. He has written many
technology & security articles, some of which have been
published in nationally circulated magazines & periodicals.
If you would like to contact Darren you can e-mail him at
Darren.Miller@ParaLogic.Net. If you would like to know
more about computer security please
visit us at http://www.defendingthenet.com.
