If you have a broadband modem or one that is supplied from your internet service provider (ISP) you can most probably connect two computers to it without needing a router. If you look at the picture of my modem below, it has a USB (blue) and a ETHERNET (yellow) port. Of course there are many other ways to connect two computers together to share files or an internet connection, however this article is about connecting two computers to one modem.
My service provider, Telstra Australia, supplied this modem to me. It came with an installation disc, which you should use to connect to the modem through the USB.

Now if you do not have a router, but have a similar modem to the one shown, you can connect two computers off the one broadband modem and thus both accessing the internet.
One computer can connect through the USB port and the other through the Ethernet.
A USB cable and and Ethernet cable come with the modem, however to connect the second computer you may need to buy a longer Ethernet cable. Get a blue cable.. NOT yellow or red. The blue one is a CROSSOVER cable, the others will be PATCH cables. They have the same connections on them but do entirely different jobs. (this colour coding applies in Australia, I don’t know about other countries.)

How to connect two computers to one broadband modem?

In this tutorial I will show you how to connect two computers to the same broadband modem.

What do you need to connect two computers?

1. You will need two computers to connect to one modem.
2. You will need an ethernet cable and a USB cable.
3. You will need a modem similar to the one pictured above.
4. You will need an internet connection.
5. You will need an installation CD to install through USB connection.

To connect a computer to a broadband modem through USB, it is recommended that you use the installation cd. It will ask you to choose how you want to connect and you select USB. Make sure you know your user name and password for your internet service provider.
To connect the second computer to the same modem but through the Ethernet, just plug it in…It usually works straight away. If it does not, use the installation cd, but choose to connect with Ethernet.
See more Computer Networking Tips

Notes on how to connect two computers:

• If you do not have an installation cd, phone your internet service provider and they will send one to you.
• See 3 other ways to connect two computers together.
• If you run into any problems, phone your internet service provider and they will help. It is perfectly OK to connect two computers to a broadband modem.