What is it?

If you have more than one home computer that you would like to have talking to each other or to the Internet, you need a home network.  Your Internet connection could be through a dial-in PPP connection, but the focus of this article is on "broadband" Internet connections, such as DSL (digital subscriber loop) from the phone company or cable modem service from the cable TV company.  The preferred type of connection within the home is Ethernet (either 10 or 100 Mbit/s versions), although wireless (IEEE 802.11b) or other types of connections are possible.

We also have an earlier write-up on how to do home networking with Linux and with a PPP dial-up connection.

Please note that "home networking" is not supported by Yale Engineering IT.   That is, we can't guarantee to make it work for you.  The information here is for the user who can manage a "do-it-yourself" project.  We will provide what advice we can, however.

Simple hook-up

The conventional setup that most commercial broadband suppliers expect you to have is for a single computer, not otherwise networked.  They supply a special DSL or cable modem that connects to your computer by a single 10 Mbit Ethernet cable.  If your computer does not have an Ethernet port, they will install one for you.  They will also normally install special software which speaks the protocols expected by the modem and the broadband service.  (Commonly, this uses the PPPoE protocol -- Point to Point Protocol over Ethernet.)

Recommended Home Network

If you do want several computers connected at once, or if you are using a laptop computer that needs to work on Yale's Ethernet as well as at home, we recommend that you install a DSL/cable modem router box, such as the Linksys BEFSR41.  This device provides all the intelligence needed to negotiate with your cable modem and your Internet provider -- i.e., to log in to their network with PPPoE.  It then presents a standardized network to your computers, allowing you to configure them with your own chosen IP addresses or to use DHCP/roaming access, just like the Yale network.

The connection scheme we suggest is the following

Your Internet provide supplies the modem, but you should not install any of their special software on your computer.  Rather, procure and connect a DSL/Cable Router as shown. We have experience with the Linksys BEFSR11/BEFSR41 product, but there are others that are equivalent.  Install as shown.  Following the manufacturer's instructions access the built in web server from your computer's browser (typically, at http://192.168.1.1) and input your Internet provider's PPPoE login information.

Your local computers should be set up for IP addresses using either a static or dynamic assignment.  Static assignment is good for machines that need to be at a predictable address, e.g., if they act as servers to other computers.  Dynamic (DHCP) assignment is good if you want to take a laptop between home and the office without changing any network settings.  (Except you may have to reboot.)

For static assignments, use a number in the non-routed block of IP numbers:

192.168.1.2 -- 192.168.1.99 (say)  (...1.1 is normally used for the router)

If you also want to use dynamic addressing for some computers, you have to enable the DHCP server function of the router using its web interface.  You will need to assign a certain range of addresses for DHCP use that do not conflict with static IPs you might be using.  I suggest

192.168.1.100 -- 192.168.1.254.

Your laptop computer should be set to get its IP address from the network, along with the appropriate DNS address.  I.e., do not specify fixed numbers, but allow DHCP to set them when you boot up.

Security

A major advantage of using the DSL/cable modem router is that it provides a "hardware firewall" between your home computers and the Internet.  Its normal setup prevents an outside person from seeing any details of your network and makes intrusion much less likely.  Some special setup is required, however, if you want to permit some outsiders to access your home systems - if you want to run a web or ssh server, for example.

Email Problem & VPN

There is one exception to the portability this system gives you for laptops moving between home and Yale.  For outgoing email, you must give the appropriate "SMTP Server" address.  With the normal networking environment, you will not be allowed to send mail from home through the Yale server (mail.yale.edu) if its destination is outside Yale.  Your Internet vendor (SNET, AT&T, etc.) will provide you with their SMTP server address, like smtp.snet.net, that will work.

You will have to change this address in Eudora's or Netscape's mail options list when you move between Yale and home.

BUT there's a way around this problem.  Use Yale's VPN (Virtual Private Networking) facility.  This is described at ITS's VPN web site. If you are at home or on the road and are attached to any commercial ISP (like your broadband service or another university), running VPN effectively sets you up as a member of the Yale network using an encrypted channel.  In this case, you would always use the Yale SMTP address (mail.yale.edu).  The VPN service is highly recommended, but it is only "free" and convenient for Windows computers, not Macs or Unix.