Microsoft Internet Security and Acceleration Server 2004 SDK

About the Microsoft Firewall Service

The Microsoft® Firewall service (fwsrv) is a generic, circuit-level proxy for Windows Sockets (Winsock) applications. The Firewall service makes Telnet, e-mail, news, Microsoft Media Player, RealNetworks RealAudio, Internet Relay Chat (IRC), and other Winsock-compatible client applications perform as though they were connected directly to the Internet. The client application makes Winsock application programming interface (API) calls to communicate with an application running on an Internet-based host. The Firewall service redirects the necessary functions to the ISA Server computer, thus establishing a communication path from the internal application to the Internet application through the ISA Server computer. This redirection eliminates the need for a specific gateway for each protocol, such as Network News Transfer Protocol (NNTP), Simple Mail Transfer Protocol (SMTP), Telnet, or File Transfer Protocol (FTP). The Firewall service allows applications with no built-in support for a proxy to benefit from proxy service without using the protocols.

The Firewall service runs as a stand-alone service on Microsoft Windows Server™ 2003 and Windows® 2000 Server operating systems. It establishes gateway connections between the Windows Sockets (Winsock) applications on the client and the Internet host. The local network remains secure, because communication is channeled through the ISA Server computer. The Firewall service can be enhanced by using application filters.

You can determine whether the Firewall service is running through the FirewallServiceStatus property of the FPCServer object. The Firewall service can be started by calling the StartFirewallService method, and it can be stopped by calling the StopFirewallService method.

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