How to enable or disable the half-open TCP connections limitations

[EricTheRed]

By default, the half-open TCP connections limit is disabled in Windows Server 2008 with Service Pack 2 (SP2) and in Windows Vista with Service Pack 2 (SP2). However there may some situation arise where you want to enable the half-open TCP connections limit in Windows Server 2008 with SP2 or in Windows Vista with SP2. Here is the registry tweak that allows you to either enable this service and also if it is already enabled then how you can disable it.

1. Click on Start button.
2. Type regedit.exe in the Search box and then press Enter.
3. If you are prompted for an administrator password or for confirmation, type your password, or click Continue.
4. Look for HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\EnableConnectionRateLimiting key and double click on it.
5. In the Value data box, type "1" to enable it or "0" to disable it and then click OK.
6. Exit Registry Editor.
7. Restart the computer.

[XDRoX]

A TCP connection is referred to as half-open when the station at one end of that TCP connection has crashed, or has otherwise removed the socket without formally notifying the other end of the TCP connection.

Half-open limit fix is a program that can also be used to change the maximum number of concurrent half-open outbound TCP connections (connection attempts) in the Windows system tcpip.sys file.

How does Half-open limit fix works:

1) Run Half-open limit fix
2) Choose a new limit of concurrent half-open outbound connections quantity and press "Add to tcpip.sys" (for most Internet users, changing the limit to 100 will be more than sufficient)
3) Restart computer