How to share your cable modem or DSL connection between two computers

or networking for dummies !  Microsoft operating systems only...you 1337 Linux people don't need this anyway, do you ?

When having a high-speed Internet connection, it makes sense to share it between several computes at the same time. Maybe your roomie, husband, wife, children or just your other personality wants to surf the web when you're on a E2 noding spree. If you have access to another computer, this can be done easily! It can also be done in many hard ways, so this is a comprehensive guide to several easy ways of accomplishing an Internet connection sharing. If you want to add more computers, you will have to create a LAN, and that is not covered in this guide. 

There are many different ways to connect two computers to each other without being a hacker, for instance

I will describe these briefly below, with pros and cons.

Networking using a hub
Using a hub to connect computers, is basically the same as building a LAN. A switch is a more competent and expensive hub. Hubs are cheap, around $30.
Pros: Fairly easy, good speed 10 or 100 MBps, comes in kits found in computer stores
Cons: Requires two IP-addresses, no security
Setup: Each PC needs one NIC that goes to the hub, which in turn is connected to the cable modem. Then the network adapters need to be configured in Windows so that the computers work well on the same network. The sharing of the connection is provided by your setup of the network and the hub.

Networking using a router
A router is needed for a more advanced network, and therefore it is harder to setup. It is also more expensive, with very few priced under $200.
Pros: Requires only one IP address, functions as a firewall, good speed 10 or 100 MBps
Cons: Expensive, harder to setup
Setup: Same as for a hub, plus that the router needs to be setup as well, according to its manual. The sharing of the connection is provided by your setup of the network and the router. You do read manuals, don't you...?

Using a direct cable connection - peer to peer or null modem connection
Direct cable connection is a supported feature of Windows, and it uses a crossover serial or parallel cable. 'Crossover' means that the cable is twisted with respect to it's internal wiring; some of the wires change places in the connector plugs. It is very easy to use the wizard to establish the connection. When the connection works, you just use Internet Connection Sharing, ICS,  which is also a Windows feature. ICS is available in Windows version 98 Second Edition and over. There are also several commercial products like Wingate that shares your connection once you have the PCs networked.
Pros: Dead simple, requires a crossover serial or parallel cable, only requires one IP address
Cons: Low speed ~ 0.1 MBps
Setup: Use a crossover serial or parallel cable, and then in Windows create a New Connection, and choose Direct Connection. Setup one PC as "Host' and one as "Guest". This done, use ICS to share the connection, as described above under "peer-to-peer".

Using a crossover network cable
This is basically the same as using the above mentioned null modem, except you connect two NICs by a crossover network cable. 'Crossover' means that the cable is twisted with respect to it's internal wiring; some of the wires change places in the connector plugs. Here too, you use Internet Connection Sharing in Windows, as described above under "peer-to-peer". One PC is setup as a host, and the other as a guest.
Pros: Fairly easy, good speed 10 or 100 MBps, only requires one IP address
Cons: Well, you might still have to fiddle with your network settings.
Setup: Install the NICs and setup up the network adapters in Windows. Then use ICS to share the connection.

USB connections
OK, this is not a separate type of connection; it's just another type of connectors that have driver support in Windows already. You can use a NIC or a modem with a USB adapter and then use a hub or a router. Or you can make a direct cable connection using a USB direct cable cable (~$50) and some software.
Pros: Easy, good speed 4-8 MBps
Cons: USB not super reliable 
Setup: Insert USB cable and then use ICS, if you use a direct connection. If connected to hub/router, see above. 


Let me know if anything is incorrect or needs clarification. I will try to add more specific setup information.

And now, the Macintosh Version!



First, all computers you wish to have access to the internet via your high bandwidth connection (Cable Modem, DSL), must be connected via a LAN (See: How to connect multiple Macintosh's to a LAN). Also, plug the DSL into your LAN.

Take one of your computers, and select it to become the router. This computer should be the computer that is least restarted, and/or shut down (If all computers are prone to crashing, use the one that is least used). Purchase IPNetrouter from Sustainable Softworks http://www.sustainablesoftworks.com.

Setup IPNetrouter to use one interface as the nonroutable IP, or LAN interface, and one as the routable IP, or DSL interface.

Let the connection begin! (and please contact me with additions, or any questions)
As with any problem found while living in a capitalist society, this one can be solved by throwing money at it. Linksys makes a perfectly workable device that does all of the required magic and can scale up to 253 hosts. The BEFSR41 has four local network ports, so you can hook up up to four computers to your 'net provider with no additional hardware. Its slick little web configuration utility is so simple to navigate that even a total imbecile should be able to set it up, while maintaining many useful options. It can do port forwarding for those of you who want to run a server on one of your machines, mixed static and dynamic DHCP allocations, and even lets you configure a fall-through host for any unmapped ports; useful for a bastion host.
The best part? It works with any platform: Windows, Mac, Linux, Sun, NeXT (yes, I've used it with all of these at once!), whatever.

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