How To Configure the ISA Server 2000 HTTP Redirector Filter in Windows 2000 (310129)

SUMMARY

This step-by-step article describes how to configure HTTP redirector filters. ISA Server 2000 can provide both firewall and Web-caching services for ISA Server clients. The Web Proxy client automatically uses the Web Caching feature. ISA Server Firewall and SecureNAT clients can also utilize the Web Proxy cache by leveraging the features that are provided by the ISA Server HTTP Redirector Filter.

The HTTP Redirector Filter is an ISA Server Application Filter that can intercept HTTP requests from Firewall and SecureNAT clients. Dependent on how the HTTP Redirector Filter is configured, Firewall and SecureNAT client HTTP requests can be redirected to the Web Proxy service, forwarded directly to the destination Web server, or dropped.

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Configure the HTTP Redirector Filter

1. In the ISA Management console, expand your server or array, and then expand the Extensions node in the left pane of the ISA Management console.
2. Click the Application Filters node in the left pane of the ISA Management console.
3. Right-click the HTTP Redirector Filter node in the right pane of the ISA Management console and click Properties.
4. In the HTTP Redirector Filter Properties dialog box, click the Options tab.
5. When the Redirect to local Web Proxy service option is selected, requests from SecureNAT and Firewall clients will be forwarded to the Web Proxy service on the ISA Server computer. HTTP Objects that are obtained from Firewall and SecureNAT clients will be placed in the cache, and Firewall and SecureNAT clients will be able to access Web objects that are placed in the Web Proxy cache.
6. When the If the local service is unavailable, redirect request to requested Web server option is selected, requests should be directed to the requested Web server. This means that the request will not be cached when the local service is unavailable.
7. The Send to requested Web server option will forward HTTP requests from Firewall and SecureNAT clients directly to the destination Web server. Web objects that are obtained from Firewall and SecureNAT clients will not be cached.
8. The Reject HTTP requests from Firewall and SecureNAT clients option will cause all HTTP requests from Firewall and SecureNAT clients to be dropped. This is a helpful option when you want to force clients to use the Web Proxy client to access Web sites and prevent users from configuring their computers as Firewall or SecureNAT clients to access Web sites.
   
   NOTE: Credentials that are provided by Firewall clients are removed when the HTTP Redirector Filter forwards a request to the Web Proxy service. If ISA Server requires authentication to access a Web object, the request will fail. SecureNAT clients do not provide credentials to the ISA Server, and because of this, the HTTP Redirector Filter does not impact its normal functioning.

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