ISA Server and IIS Server

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The Web Proxy service (w3proxy) of Microsoft Internet Security and Acceleration (ISA) Server runs as a Windows 2000 service. The process is initialized by starting the Web Proxy service. Microsoft Internet Information Services (IIS) can be installed on an ISA Server computer, but it is not required.

You can configure ISA Server to listen for incoming Web requests and outgoing Web requests on different ports, by configuring the properties in Servers and Arrays. For example, by default, ISA Server listens for outgoing Web requests on TCP port 8080. In this way, ISA Server ensures that outgoing Web requests do not interfere with Web publishing on port 80. For configuration instructions, see Configure the TCP port.

If IIS is installed on the ISA Server computer, you can publish IIS by configuring Web publishing rules. In this case, IIS must be configured not to use the ports that ISA Server uses for outgoing Web requests (by default, port 8080) and for incoming Web requests (by default, port 80). For example, you can change IIS to listen on port 81. Then you can configure the ISA Server computer to listen for incoming Web requests on port 80 and create a Web publishing rule that directs the incoming Web requests to port 81 on the local IIS server. For more information, see Web publishing rules. For a scenario illustrating this, see Web server on the ISA Server computer.

Alternatively, IIS can continue to listen for incoming Web requests on port 80. In this case, configure an Internet Protocol (IP) packet filter, which maps incoming requests on TCP port 80 to IIS. For more information, see IP packet filters. For a scenario illustrating this, see Using packet filters to publish a Web server on the ISA Server computer

To avoid any potential conflict between ports used by ISA Server and those used by IIS, the setup program stops the World Wide Web Publishing service (w3svc). After ISA Server is installed, you can change IIS to listen on a different port and then restart the IIS publishing service.