For the purpose of this example, I’m going to assume that we’re using NAT overloading (PAT) to allow our internal clients to access the Internet through a single public IP address. We’ll also create a static inbound mapping to allow external clients to gain access to a web server on our private network. The network […]

While NAT is most commonly looked at as a way to allow internal clients to gain access to the Internet, it can also be used to allow external Internet hosts to gain access to resources on a private network. Recall that by default, a NAT server will drop all packets that are not replies to […]

Overloading is a very popular NAT technique, and is sometimes referred to as Port Address Translation (PAT). Instead of requiring multiple public IP addresses, overloading instead uses a single (or small number) of public address, and differentiates between sessions according to port number. When a client on the internal network wishes to access the Internet, […]

Dynamic NAT works slightly differently in that private and public addresses are not mapped on a one-to-one basis. Instead, a range of public IP addresses is configured on the NAT device, and private internal clients will be mapped to an available address as necessary. The NAT table is built dynamically, avoiding the need for mappings […]

A static NAT implementation is one in which each private internal IP address is mapped to unique public external IP address. This technique involves defining a static NAT table on the router that maps each internal private address to its external public counterpart. Consider the example illustrated in the figure below. It shows a small […]

In Chapter 5 we took a look at how companies have moved to using private IP addresses on their internal networks. The reason for this transition is twofold. Firstly, the rapid growth of the Internet has led to a serious reduction in the number of public addresses available in the IP version 4 address space. […]

One topic that seems to cause users a great deal of anguish is the configuration of Network Address Translation (NAT) for the purpose of providing shared Internet access on private network. This guide is meant as a quick reference for those who need to implement NAT on networks, especially small networks that include Active Directory.
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Windows 2000 Server also includes another solution similar to ICS but more robust, in the form of the Network Address Translation protocol in Routing and Remote Access. While it basically consists of the same functional elements as ICS (and works in a very similar manner), NAT has some additional features that may make it a […]

A service first provided by Microsoft in its Windows 98 operating system, Internet Connection sharing is meant to allow a single Internet connection to be shared amongst multiple computers on a small network with minimal configuration. In Windows 2000, ICS is implemented via the actual sharing of a network interface, which has a ‘real’ IP […]

Internet Connection Sharing (ICS) is a feature in Windows 2000 very similar to the same feature found in the second edition of Windows 98. With ICS, you can share a remote network connection from one machine with other machines on your single-subnet network. Essentially, ICS configures your Windows 2000 system as a Network Address Translation […]