Windows XP SP2 and Event ID 4226April 29, 2005
Keywords: tcpip connection limit Windows XP SP2 Event ID 4226 patch lvlord
You can find out which process is responsible for the many half-open connections with the command 'netstat -no | find "SYN"'. Half-open connections will have a state of other than ESTABLISHED. Note the PID (process id), open Task Manager and locate the process and application responsible for the half-open connections.
The second case means that SP2 is stalling your work. An unofficial patch will modify the locked tcpip.sys and let you set the limit to whatever you wish. 50 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: LVLlord downloads.
Certain Microsoft updates may replace the TCPIP.SYS with a new locked version but LVLLord has been quick on updating the patch. When you run the patch, it will tell you how many connections are currently allowed.