Internet Connection Sharing or ICS is the service
found on Windows 98, 98 SE, Me, 2000, XP, and .NET that allows
a single Internet (or other network connection) to be shared
with a small network. If you have branch offices with small
office networks, ICS is an inexpensive way to take full advantage
of cheap broadband access. If you have DSL, ISDN, cable, or
even satellite Internet access, your service is typically configured
to allow only a single system to communicate over that link.With
ICS, you can easily share that underused link with multiple
computers.The basics of ICS are fairly basic.
1. You need the Internet connection. It can
be a modem, an ISDN card, or a NIC connecting to a DSL or cable
router/modem.
2. You need a separate NIC for your local network
connection. In most cases, you'll be using twisted pair cabling
and thus will need a switch to connect your network together.
Every other system which will be added to
the network also needs a NIC. The way ICS works is basically
it transforms your primary system (i.e. the one with the Internet
connection) into a TCP/IP router.
In addition to this, it also adds DNS forwarding and basic DHCP
services to the primary system. It is very important not to
attempt to use ICS on a network where an existing DNS server
or DHCP server is present.
NOTE: Also, do not install
(in the case of Windows 98, SE, or Me) or enable (in the case
of Windows 2000, XP, or .NET) ICS on more than one system on
the same network. Doing so will cause problems.
The documentation for ICS states that once
enabled, the external interface on the primary system (i.e.
the one connected to the Internet) will be assigned an IP address
by your ISP (which can be statically assigned or dynamically
assigned upon connection). However, the internal interface will
be assigned the private IP address of 192.168.0.1. The documentation
goes on to state that all of the clients that will use ICS to
gain Internet access will need to be configured to obtain their
IP address configuration dynamically (i.e. by using DHCP).
However, I have found that this is not the
case, and you can statically assign IP addresses to the other
clients. If you do statically assign IP addresses to the ICS
clients, you must be sure that you don't accidentally assign
the same IP address to multiple machines. Second, you must define
the same subnet mask and gateway on each system -- namely 255.255.255.0
and 192.168.0.1 respectively. Depending on the performance capabilities
of the primary system and the speed of the Internet connection
you can easily use ICS to grant 2 to 20 local clients Internet
access over your network. |