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How to: Replace the WCF URL Reservation with a Restricted Reservation

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A URL reservation allows you to restrict who can receive messages from a URL or a set of URLs. A reservation consists of a URL template, an access control list (ACL), and a set of flags. The URL template defines which URLs the reservation affects. For more information about how URL templates are processed, see Routing Incoming Requests. The ACL controls what user or group of users is permitted to receive messages from the specified URLs. The flags indicate whether the reservation is to give a user or group permission to listen on the URL directly or to delegate the permission to listen to some other process.

As part of the default operating system configuration, Windows Communication Foundation (WCF) creates a globally accessible reservation for port 80 to enable all users to run applications that use a dual HTTP binding for duplex communication. Because the ACL on this reservation is for everyone, administrators cannot explicitly allow or disallow permission to listen on a URL or set of URLs. This topic explains how to delete this reservation and how to re-create the reservation with a restricted ACL.

On Windows Vista or Windows Server 2008 you can view all of the HTTP URL reservations from an elevated command prompt by typing netsh http show urlacl. The following example shows what a WCF URL reservation should resemble.

Reserved URL : http://+:80/Temporary_Listen_Addresses/
        User: \Everyone
            Listen: Yes
            Delegate: No
            SDDL: D:(A;;GX;;;WD)

The reservation consists of a URL template used when a WCF application is using an HTTP dual binding for duplex communication. URLs of this form are used for a WCF service to send messages back to the WCF client when communicating over a HTTP dual binding. Everyone is given permission to listen on the URL but not to delegate listening to another process. Finally, the ACL is described in Security Descriptor Definition Language (SSDL). For more information about SSDL, see SSDL

To delete the WCF URL reservation

  1. Click Start, point to All Programs, click Accessories, right-click Command Prompt and click Run as Administrator on the context menu that comes up. Click Continue on the User Account Control (UAC) window that might ask permissions to continue.

  2. Type in netsh http delete urlacl url=http://+:80/Temporary_Listen_Addresses/ in the command prompt window.

  3. If the reservation is deleted successfully, the following message is displayed. URL reservation successfully deleted

Creating a New Security Group and New Restricted URL Reservation

To replace the WCF URL reservation with a restricted reservation you must first create a new security group. You can do this in one of two ways: from a command prompt or from the computer management console. You only have to do one.

To create a new security group from a command prompt

  1. Click Start, point to All Programs, click Accessories, right-click Command Prompt and click Run as Administrator on the context menu that comes up. Click Continue on the User Account Control (UAC) window that might ask permissions to continue.

  2. Type in net localgroup "<security group name>" /comment:"<security group description>" /add at the command prompt. Replacing <security group name> with the name of the security group you want to create and <security group description> with a suitable description for the security group.

  3. If the security group is created successfully, the following message is displayed. The command completed successfully.

To create a new security group from the computer management console

  1. Click Start, click Control Panel, click Administrative Tools, and click Computer Management to open up the Computer Management Console. Click Continue on the User Account Control (UAC) window that might ask permissions to continue.

  2. Click System Tools, click Local Users and Groups, right-click Groups folder and click New Group on the context menu that comes up. Type in the desired Group Name, Description and other details of this new security group and click the Create button to create the security group.

To create the restricted URL reservation

  1. Click Start, point to All Programs, click Accessories, right-click Command Prompt and click Run as Administrator on the context menu that comes up. Click Continue on the User Account Control (UAC) window that might ask permissions to continue.

  2. Type in netsh http add urlacl url=http://+:80/Temporary_Listen_Addresses/ user="<machine name>\<security group name> at the command prompt. Replacing <machine name> with the computer name on which the group must be created and <security group name> with the name of the security group you created previously.

  3. If the reservation is created successfully, the following message is displayed. URL reservation successfully added.