Sharing an Internet Connection and Protecting it!

Yet another wireless guide to help and answer your questions and concerns. This is the 3rd guide also. Again note: This is for Windows XP users for when I mention things concerning to wireless on the laptop that must be set up on the laptop.
This guide only covers ICS and Firewalls because this is more sharing an Internet connection topic. Next guide should more in depth and more detail. This is really basic connection sharing and safety of sharing.
Sharing an Internet Connection
Your Internet connection and home network will be wonderful with all the good things you can do with home networking technology; after the connections are in place, its time to begin taking advantage of those connections, primarily in the form of resource sharing. And the most important resource you can share is your internet connection.
With a shared connection, all the machines on your home network can access the web, instant message, email, and all other things that are available online.
Connection Sharing
The concept of sharing an internet connection dates back a few years to a low-level technology called Network Address Translation {NAT}. This technology was designed to overcome the limitations of IP addressing, in that it became apparent by the mid 1990s that the number of free IP addresses would soon be depleted by the internet. As a result, certain ranges of IP addresses were aside solely for internal use at corporations and homes. These private, internal IP addresses can’t see the outside world-the internet-without being somehow translated into more typical external IP address.
Enter NAT, a network service that sits on the edge machine of a network and translates private, internal IP addresses into a single external IP address, and vice-versa. First used in servers, and then later in desktop machines for home networking use, the NAT service typically presents a single IP address to the outside world, obscuring the number of machines on the home network can interact seamlessly with internet services.
There are disadvantages to NAT, however. Because each machine on a home network is not seen as a unique Internet host, some internet services will not work properly through a NAT connection. However, many NAT devices, including home gateways and even PC operating systems such as Windows XP, can forward certain requests to certain local machines if you want. For example: if you have a Web server on a particular machine on your home network, you can configure your NAT device to forward Web server requests to the proper machine. But other services cannot be fooled so easily. 
Introducing Internet Connection Sharing (ICS)
Microsoft first added simple NAT capabilities to its desktop operating systems as Internet Connection Sharing (ICS). ICS was introduced with Windows 98 Second Edition (SE), and also appeared later in Windows 2000 Pro, in Windows Millennium Ed. (ME), and now, in Windows XP.
ICS is basically a super simple front end of NAT. In fact, it’s so simple that one checkbox in the user interface can enable it. After ICS is enabled, you can share an Internet connection from your XP machine among other machines on your home network.
For ICS to work, you need at least two network connections, as follows:
A modem connection or network interface card (NIC), which is physically connected to your phone line or broadband connection. This connection manages the Internet connection component.
A second connection to your internal network; typically through a hub or switch; this connection; which will typically be an Ethernet or wireless network connection, manages the connection between your PC and the different computers on your home network. Each computer on the network uses this connection to get to the computer that is managing the Internet through the first network connection listed above.
To set up and configure Internet Connection Sharing, you must ensure that your physical connections are correct. Then open Network Connections by clicking Start and then right click My Network Places and selecting Properties. The Network Connections window shows you all the connections that are present in your system, including any modem connections, NIC’s (wired or wireless), or FireWire/IEEE-1394 adapters.
By default, Windows XP provides simple names for each of the Network connections. If you have two NIC’s, for example, they will be named Local Area Connection and Local Area Connection 2, which aren’t very descriptive. You should rename these. I recommend names such as Cable Modem Connection for your external Internet connection, while Local Area Connection is fine for the internal connection.
I didn’t want to get in much detail because I think you should never do this because:
I just wanted to give you an explanation of ICS if there were any questions about it.
These days, hackers are pyling the internet, looking for unshielded, directly connected computers to which they can deliver their vile malware surreptitiously. But using hardware sharing solution, like that provided by a residential gateway device, physically separates your home network from the internet and provides a level of protection you don’t get from software only solution like ICS. Better yet, residential gateways provide a number of other useful services and are extremely cheap. Everyone with a home network should be using a residential gateway.
Put simply, using a Windows XP based PC as the edge machine isn’t practical. In addition to the security risks mentioned previously, there are other reasons why you wouldn’t want a PC on the edge of your network. Your whole network will lose its internet connection, for example, if the edge PC isn’t running or something goes wrong. Instead, a hardware solution, such as a residential gateway or broadband router, can be used to shield the home network from the outside world and provide NAT/Internet Connection Sharing Capabilities.
Working with Firewalls
Large corporations use a hardware device called a Firewall to protect internal networks from outside problems, including unwanted network traffic and other more targeted Internet based attacks. But with the proliferation of broadband internet connections, home users also need protection from internet borne attacks, so the hardware firewalls of the past have been downsized into software applications that are now available on PCs.
Simply diagram of how firewall works

Cable Modem/DSL/Modem ~ NIC ~ Firewall (Software) ~ Computer ~ NIC ~ Switch ~ to another PC on the local network.
Not as in depth as my other guides but you will be looking forward to the next one! Just wanted to get this info said and done. THANK YOU!
Let me know if you would like more info on ICS and Firewire because i will gladly give you more info!

 

Looks great. I'll sticky this.

 

Thanks Aurora! I appreciate it!