Patch Half-Open TCP Connection
January 28, 2008
Microsoft Windows XP Service Pack 2 introduces a limited TCP connection, which is set to a maximum of 10 (the previous limit was over 65,000). This is “supposed” to protect the host PC from connecting to a high amount of random IP numbers.
Since some malicious worms could spread by connecting to a high amount of random IP numbers, Microsoft, in their infinite wisdom, introduced a patch in SP2 to limit the TCP connection to 10.
Regrettably, this also slows down application that relies on many connections (such as the BitTorrent client). This limit has the potential to cause slowdowns in certain situations.
An unofficial patch will modify the locked tcpip.sys and let you set the limit to whatever you wish. 75 half-open connections is a reasonable limit or you can set the limit back to 65,535 which it was before the SP2. The patch is called EventID 4226 Patcher and can be found on LVL Lord’s web site.
Just bear in mind that every time you update Windows, it will revert back to the original connection number (i.e. 10). So my recommendation is that once you have updated Windows, run the patcher again to change the number of maximum connection.
