Implementing ISA Server in Firewall Mode

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

ISA Server in firewall mode acts as a secure gateway between the Internet and internal clients. By configuring the access policies, you can prevent unauthorized access and malicious content from entering the network, as well as restrict outbound traffic.

In Figure 5.3, ISA Server is deployed in firewall mode and as a publisher of internal services, including e-mail and Web services.

Figure 5.3   ISA Server in Firewall Mode

All inbound traffic requiring access to the Web or e-mail servers must pass through the firewall first. Likewise, ISA Server can also limit Internet access to specified clients. In this example, ISA Server is acting as a dedicated firewall controlling access to the internal network.