Updated: January 13, 2001
Here's how to setup Internet
Connection Sharing or ICS in windows 2000. ICS is useful as long
as the host computer is always on. If the host machine is turned
off or rebooted, all of the computers are then disconnected from Internet
for that period of time.
Another limitation of ICS
is that you are limited to sharing the connection to 10 clients, which
may be too few, depending on your needs. A hardware router solution
such as the Linksys 4 port DSL/Cable router can share the connection with
up to 253 users.
ICS has many benefits such
as being a basic firewall to keep intruders out. It is also free
so you do not need to pay for hardware routers.
The first thing you need
to do is install two Network Interface cards (NIC) in your computer.
I suggest that you buy two different brands of network cards instead of
two identical ones because Windows will give them the same name.
If you're lucky, Windows may label one card #1 and the other #2.
Once you install both cards (install the NIC, drivers, etc) we need to
configure it.
Go to Start -> Settings ->
Network and Dial-up Connections and you'll see both NIC's and whichever
dial-up connection you have, in my case it is a dial-up to USC's modem
pool.
You'll notice that each NIC
has it's own name and in our example, it is "3com" and "Realtek".
I find this confusing so
I changed the names to "WAN" for Wide Area Network (connects to the Internet)
and "LAN" for Local Area Network (the network inside my house). This
is just for my own convenience, you can leave the names alone or call them
"Ren" and "Stimpy". Whatever makes sense to you.
Next, connect your DSL or
Cable connection to the network adapter labeled WAN and follow the instruction
your ISP gave you. To configure the NIC, you double click on the
"WAN" icon and then click on "Properties". Here you will be able
to install protocols, clients, and setup your TCP/IP.
The after you configure your
WAN adapter, you may be required to restart your computer. After
you reboot, you need to launch a web brower to see if you can connect to
the Internet.
Assuming that everything
worked fine and you were able to connect to the Internet, let's now share
this connection across the other network card.
ICS works by connecting
one network card (WAN) to your broadband connection and the other to your
home network (LAN) so share the Internet connection. In order for
this to happen, the second network card needs to be connected to a hub
or switch which is connected to the rest of your network.
Mentally walk with me through
this one: The connection comes from the mystical wall (DSL or CABLE)
and enters your DSL or Cable Modem. It then goes INTO your WAN network
card in your server then OUT your LAN network card to a hub or switch to
which the rest of your computers are connected. Easy yeah?
In order for your WAN network
card to share the Internet connection, it acts like as a DHCP Server which
basically hands out IP numbers to your LAN computers (client computers).
You must configure each client computer to obtain an IP address automatically
from the DHCP Server. We'll come back to this.
Now were are going to share
you connection. In order to do this, go to your WAN icon and double
click on it. (NOT the LAN icon!) Hit properties, and you will
see two tabs "General" and "Sharing" When we were configuring the
WAN network card for DSL or CABLE modem, we used the "General" tab.
Click on the "Sharing" tab and you'll see this:
Check the box "Enable Internet
Connection Sharing for this Connection".
Click "OK". You will
get this warning:
Basically the warning says
this computer will now be a DHCP server (this computer will assign IP numbers
to the other client computers) and that all your client computers must
be set to obtain an IP address automatically. They cannot be using
a static IP address and work with ICS,
Click "OK" to continue.
Network Security
ICS configuration now should
work. Each client computer must be set to obtain a IP address automatically.
Give the client computer a reboot and upon loading, it will get an IP address
from your ICS host computer.
Note: ICS does not need to
be loaded on the client computers. Only the computer that is directly
connected to the Internet connection needs to have ICS installed.
This was very confusing to me at first!
However, we still need to
setup the network for security. You want to keep your WAN connection
very secure, but can relax security on the LAN side. For example,
you want to have file and printer sharing on your Local Area Network, but
not across the whole Internet, right? (Wow, imagine the whole world
sharing your laser printer. That could cost you billions!)
This part is nice and easy.
Double click on the WAN
icon -> click on properties. In the window you will have a list of
protocols and services that are attached to that network adapter.
Uncheck every box except TCP/IP. TCP/IP is necessary to connect
to the Internet. It should look like this:
The LAN network card can
have whichever protocols and services you want since it is on your local
network. The only required protocol is TCP/IP, the rest are optional.
One final check before we
finish. Go to the Command prompt: Start -> Programs -> Accessories
-> Command Prompt and enter the following: ipconfig /all
You will see a summary of
all your networking information.
Under WAN, you will see the
IP address your DSL/Cable host assigned to you or your static IP number.
Under LAN, you see the IP
number of 192.168.0.1
This is the IP number of
your server computer when accessed from INSIDE your network. ICS
will assign each client computer in your network an increment of the original
IP number. (192.168.0.2, 192.168.0.3).
Now your whole local area
network (up to 10 people) can share one connection to the web. Hopefully
it's a fast one!
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