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Important This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/256986/ )Description of the Microsoft Windows registry
This article discusses how to use named pipe filters in Microsoft Windows XP Service Pack 2 (SP2), in Microsoft Windows Server 2003 Service Pack 1 (SP1), and in later versions of these operating systems.
A pipe is a technique for passing information from one program process to another program process. Unlike other forms of inter-process communication (IPC), a pipe is a one-way communication. For example, a pipe passes a parameter, such as the output of a process, to a second process. This second process accepts the output of the first process as input. Then, the operating system temporarily holds the piped information until the receiving process reads that information. For two-way communication between processes, you can set up two pipes. In this scenario, one pipe faces one direction, and the other pipe faces the other direction.
However, there is a limitation of pipes for IPC. The limitation occurs when the processes that use pipes have a common parent process. Therefore, they must share a common open process or initiation process. Then, they must be created by a fork system call from a parent process. A pipe's size is at least 4,096 bytes.
A named pipe is an extension of the traditional pipe. A traditional pipe is unnamed because it exists anonymously. It persists only for as long as the process runs. A named pipe is system-persistent and exists beyond the life of the process. You must unlink or delete the named pipe when it is no longer being used. Processes, such as a file, generally attach to the named pipe to perform IPC. Named pipes are closely related to "device special" files. Like "device special" files, pipes do not refer to actual data that is stored in the file system.
Named pipe filtering service was introduced in Windows XP SP2 and in Windows Server 2003 SP1, and is available in later versions of these operating systems. Named pipe filtering service is used to enable or to block access to named pipes. Information about how to enable named pipe filtering is discussed in the "More Information" section.
Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
Enable dynamic filtering of named pipesTo enable dynamic filtering of named pipes, create the PipeFirewallActive registry entry, and set the value to 1 for this entry. Then, you do not have to restart the computer. To do this, follow these steps:
Create a list of named pipesTo create a list of named pipes that you can access, add the list of named pipes as values for the AllowedPipes registry value. Then, you do not have to restart the computer. To do this, follow these steps:
Remove a named pipe from the "AllowedPipes" listTo remove a named pipe from the AllowedPipes list, follow these steps:
In the release version of Windows Server 2003, the following named pipes are hard-coded and cannot be disabled:
Named pipes for a file server or for a print serverThe following named pipes are required for the server to function only as a file server or as a print server:
Named pipes that are used on domain controllersIf the AllowedPipes list is empty and the PipeFirewallActive registry entry is set to 1, you must manually add the following named pipes: