CrackTcpip.sys is a driver based patcher for Windows Vista tcpip.sys to increase the limit the concurrent half-open TCP/IP connection attempt the operating system can make. CrackTcpip.sys does not modify original tcpip.sys in any way. It’s a memory-resident driver program that constantly monitor a memory location that stores the value of the limit, and change the default value to a higher number (255) on the fly.

Download (no longer required).

This version of CrackTcpip.sys works and supports Windows Vista SP1 RC Refresh v.744 (build version 6001.17128) and Refresh 2 (build version 6001.18000). SP1 version 6001.18000 is also widely believed to be the final version build number for Windows Vista Service Pack 1 RTM release too, thus if there is no change to tcpip.sys on SP1 RTM when it’s officially released, the CrackTcpip.sys will be able to work on Vista SP1 RTM too.

For more information, installation steps, uninstallation instructions and user guide, visit the original page.

Note: Since Windows Vista and Windows Server 2008 SP2, there is no more restriction (now unlimited) concurrent half open TCP/IP connection limit.