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HttpWebRequest.UnsafeAuthenticatedConnectionSharing Property


Gets or sets a value that indicates whether to allow high-speed NTLM-authenticated connection sharing.

 property bool UnsafeAuthenticatedConnectionSharing { bool get(); void set(bool value); };
public bool UnsafeAuthenticatedConnectionSharing { get; set; }
member this.UnsafeAuthenticatedConnectionSharing : bool with get, set
Public Property UnsafeAuthenticatedConnectionSharing As Boolean

Property Value

true to keep the authenticated connection open; otherwise, false.



WebRequest, HttpWebRequest, ServicePoint, and WebClient are obsolete, and you shouldn't use them for new development. Use HttpClient instead.

The default value for this property is false, which causes the current connection to be closed after a request is completed. Your application must go through the authentication sequence every time it issues a new request.

If this property is set to true, the connection used to retrieve the response remains open after the authentication has been performed. In this case, other requests that have this property set to true may use the connection without re-authenticating. In other words, if a connection has been authenticated for user A, user B may reuse A's connection; user B's request is fulfilled based on the credentials of user A.


Because it is possible for an application to use the connection without being authenticated, you need to be sure that there is no administrative vulnerability in your system when setting this property to true. If your application sends requests for multiple users (impersonates multiple user accounts) and relies on authentication to protect resources, do not set this property to true unless you use connection groups as described below.

You may want to consider enabling this mechanism if your are having performance problems and your application is running on a Web server with integrated Windows authentication.

Enabling this setting opens the system to security risks. If you set the UnsafeAuthenticatedConnectionSharing property to true be sure to take the following precautions:

  • Use the ConnectionGroupName property to manage connections for different users. This avoids the potential use of the connection by non-authenticated applications. For example, user A should have a unique connection group name that is different from user B. This provides a layer of isolation for each user account.

  • Run your application in a protected environment to help avoid possible connection exploits.

If you control the back-end server, as an alternative you might consider turning off authentication persistence. This increases performance to a lesser degree, but it is safer. For more details, see AuthPersistence.


If both PreAuthenticate and UnsafeAuthenticatedConnectionSharing are set to true, each request is sent using a connection from the unsafe pool, but with an Authorization header.

Applies to