How do I Remove the Concurrent Connections Limit in Windows XP?

How do I Remove the Concurrent Connections Limit in Windows XP?Windows XP introduced the limiting of the number of possible TCP connection attempts to ten per second. This is likely to affect server and P2P programs which constantly needs to open as many outbound connections as it can at the same time.


The Limitations
Many users believe that they should have the option to disable or change this setting, making this new implementation is cause for concerns. If a P2P or some other network program tries to connect to fifty sites at once, the maximum it will be able to connect to per second would be is ten.

If you notice a slowdown in those network programs requiring a certain number of connections to be opened at once, it is due to the limit imposed. It is possible to increase the number of connections per second by modifying it directly in the system file, tcpip.sys. However, because that file is constantly in use, you will need to be in Safe mode to be able to edit it.

You are can check to see if you are getting close to this limit from the Event Viewer. Under System you look for TCP/IP Warnings saying, "TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts". This is a cap on incomplete outbound connect attempts per second only, not on total connections.

Change or remove the Concurrent Connections Limit in Windows XP
Method 1:
You can use the following program:

Download the software patch XP SP2

Edit tcpip.sys manually to remove the TCP/IP socket creation limit
Method 2:
Another method that you can use is to modify your tcpip.sys file manually. These instructions refer to the final release of XP SP2, with a tcpip.sys file of exactly 359,040 bytes, CRC-32 is 8042A9FB, and MD5 is 9F4B36614A0FC234525BA224957DE55C.

It is possible that there will be multiple tcpip.sys files in your system, make sure to work with the one in c:\windows\system32\drives\ directory.

To remove the tcpip.sys socket creation limit backup your original tcpip.sys file before you begin the editing, this is very important.

In your hex editor, go to offset 4F322 hex (or 324386 decimal). Then change 0a 00 00 00 to 00 00 0a 00.