UNC connections are denied access

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1

The Universal Naming Convention (UNC) authentication method, also called UNC Passthrough authentication, determines the credentials to be used for gaining access to a UNC share on a remote computer. Beginning with IIS 6.0, the UNC authentication looks at the request user and the credentials stored in the UNCUserName Metabase Property and UNCPassword Metabase Property properties of the metabase to determine the credentials to pass through to the computer with the UNC share, in the following way:

1. If UNCUserName is specified (not empty) and UNCPassword is valid, the metabase user credentials are sent as the user identity for access to the remote share. If UNCUserName is specified (not empty) and UNCPassword is not valid, a 500 Internal Server Error: Invalid Username or Password message is sent to the client.

2. If UNCUserName is empty, then the credentials of the request user (either an authenticated set of credentials for authenticated requests or IUSR_computername credentials for anonymous requests) are sent as the user identity for access to the remote share.