Microsoft KB Archive/245475

= Microsoft Posting Acceptor Does Not Work Through Proxy Server 2.0 =

Article ID: 245475

Article Last Modified on 4/26/2000

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APPLIES TO


 * Microsoft Proxy Server 2.0 Standard Edition

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This article was previously published under Q245475



SYMPTOMS
Microsoft Posting Acceptor is an add-on component for Microsoft Internet Information Server (IIS) 4.0 that enables the use of HTTP Post to publish content to an IIS Web server. When you attempt to upload a file to an IIS Web server using Posting Acceptor from a client that is located behind a proxy server, you may receive one of the following error messages:

Error 401 - Authorization required

Error 403 - Forbidden.



CAUSE
This behavior occurs because IIS uses the NTLM authentication protocol by default to authenticate clients attempting to post content to the Web server. The NTLM authentication mechanism requires a persistent, end-to-end connection between the client and the server to work properly. By nature, a proxy server breaks this implied end-to-end connectivity because it makes a new request to the Web server on the client's behalf. When a client attempts to authenticate with a Web server using NTLM through an HTTP proxy, authentication is unsuccessful.



RESOLUTION
To resolve this issue, configure the Web server to authenticate clients using Anonymous Authentication instead of NTLM. For detailed steps about how to change the authentication mechanism IIS uses for file uploads to Anonymous, refer to the following Microsoft Knowledge Base article:

179566 How to Do Anonymous Uploads

Additional query words: fail fails

Keywords: kberrmsg kbenv kbprb kbpending KB245475

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