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You are repeatedly prompted to enter your credentials to use a proxy server in Internet Explorer Service Pack 1
Article ID: 822458 - View products that this article applies to.
After you type your credentials to use a proxy server to view a Web site, you may be prompted to type your credentials again.
This problem may occur if you use Windows NT LAN Manager (NTLM) authentication with more than one proxy server. Microsoft Internet Explorer does not support NTLM authentication with more than one proxy server where NTLM authentication is required on each proxy server. The NTLM authentication on the first proxy server in the chain succeeds, but when the proxy server sends a "407 Proxy authentication required" response, the user is prompted for credentials. This problem occurs with any proxy server product regardless of the manufacturer.
To work around this problem, configure NTLM authentication on the downstream proxy server in the chain, and configure the downstream proxy server in the chain to pass credentials to the upstream proxy servers.
Microsoft ISA ServerIf you use Microsoft Internet Security and Acceleration (ISA) Server, follow these steps to configure the downstream ISA Server-based server to pass credentials upstream:
Third-party proxy serverIf you use a third-party proxy server in the chain of proxy servers, you must follow the steps that your proxy server manufacturer gives you to configure the downstream proxy server in the chain to pass credentials to the upstream proxy servers.
Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.
For information about your hardware manufacturer, visit the following Web site:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Article ID: 822458 - Last Review: December 3, 2004 - Revision: 1.4