Connection-Sharing Question
Hi Fred, A while back you had mentioned that you have a bare bones cheap PC with nothing much on it that is connected to the internet and the rest of your hardware all sits behind this machine. I have a hard time understanding how this configuration is set up. Do you use 2 NICs in this first PC? Could you please cover this sometime in the newsletter?
I am a plus subscriber and in the relatively short time I have been subscribed, I have thoroughly enjoyed every one of the newsletters. ---Raghu Tumkur
In the most common kinds of setups, you need a local network over which to share the internet connection, and that; by itself, requires one "network interface card" (NIC) in each PC on the LAN. If you connect to the internet by dial up, then you also need a modem and a phone line on the PC that will be doing the sharing. If you connect by cable or dsl, then you need a second network card in the machine doing the sharing.
To share the connection, you use special software that sits as an intermediary between the LAN and the internet connection, translating the LAN addresses so that, to the outside world, everything appears to be coming only from the main, connected PC. But the software also works in reverse, so inbound packets also are translated and shunted to the correct machines on the LAN. This technology is called "network address translation" (NAT). I've grossly simplified the explanation here; see http://en.wikipedia.org/wiki/Network_address_translation for more detail.
Because NAT technology disguises the true LAN addresses, it has the extra benefit of adding a modest layer of security to your connections. That's the benefit you're referring to; and indeed, I use a NAT here in my own office, for instance: I have a dedicated cheap, slow, old white-box PC (with nothing vital on it) actually making the connection to the outside world; all my other PCs connect to the internet *through* that PC. The outside world--- including would-be hackers and crackers--- "see" only the old, junk PC, if they see anything at all. The LAN-side PCs are effectively invisible from outside. (See http://www.informationweek.com/story/showArticle.jhtml?articleID=180203313 )
For the last several versions, Windows has had an "Internet Connection Sharing" (ICS) tool built in; a simple NAT that does a perfectly acceptable job in many cases. It also integrates well with XP's built-in firewall; a plus for those looking for easy setup and maintenance of a shared connection:
Setting up Internet Connection Sharing
http://www.annoyances.org/exec/show/ics
Internet Connection Sharing with Windows XP
http://www.microsoft.com/windowsxp/using/networking/expert/crawford_02july01.mspx
General search:
http://www.google.com/search?q=internet+connection+sharing
There are other technologies that accomplish the same thing, such as proxies, routers, and so on; but in many, many cases, a simple NAT (such as Windows' built-in ICS) is all you need.
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