I have two Ethernet ports - how can I use them ?

Some Internet Service Providers still supply a 'single port' Ethernet connected broadband modem which has no capability to share Internet access to a Local Area Network.  This is especially common with some Cable providers or with users who are unaware of the other options for their networks and in such scenarios the user has a broadband modem connected directly to their computer, often with no firewall.

For instance, the cable provider expects users to purchase additional modems for each additional user who wishes to use the Internet connection and along with that costly installation of additional cable outlets within the premises.

For DSL Internet, the hub topology of Hybrid Fibre/Cable (HFC) Internet is not applicable as it is a point to point topology. Internet providers supply (usually at additional cost) applicable networking devices such as all in one broadband gateway/routers so that users may share their DSL Internet connection throughout their premises.

For a user who has a directly connected cable modem and a system with multiple Ethernet ports (either integrated or add in cards), they may configure the system to share the Internet connection to their Local Area Network without the need of extra equipment.

Or, if your preference is to use a dedicated PC as a Internet Gateway/Router/Firewall device instead of an all-in-one or dedicated unit, the computer can be equipped with one of many software packages or specific purpose operating systems to achieve this goal

This is especially popular with power users, enthusiasts or corporate who prefer to use a dedicated PC for these tasks instead of all in one solution. Benefits in this scenario include increased performance, improved scalability, flexibility,security and ease of applying updates or patches.

Network Address Translation - Windows Internet Connection sharing

For the Windows platform : Windows 98/ME , Windows 2000, Windows XP, Vista and their Derivatives share a easy way to share an Internet Connection between a dial-up modem and Ethernet Adapter, or dual Ethernet adapters.

This feature is called Internet Connection Sharing and provides the same functionality for free that was once the domain of pay-ware products from companies such as Sygate

On Windows XP and newer, the Network Setup Wizard provides a simple, straightforward and secure way to set up Internet Connection Sharing between a Dial up or DSL modem and a Network adapter or between Network Adapters

Advanced Users may also manually configure this feature using the following property tabs in their Network Adapters

Windows Internet Connection Sharing, Smoothwall Linux, Windows Server and generic Linux/Unix derivatives and BSD are popular choices or alternatives.

Windows Server and Linux/Unix offer a more fully featured Network Address Translation/Port Address Translation solution which is more suitable for larger networks and larger numbers of users.

The workstation versions of Windows NT such as 2000 and XP Professional are intended for use with smaller workgroups such as of 10 nodes.