When Windows XP Service Pack 2 was released, it came together with a new feature to TCP/IP in order to babysit users and “reduce the threat” of worms spreading fast without control. In one such attempt, the devs have limited the number of possible TCP connection attempts per second to 10 (from unlimited in SP1). This argumentative feature can possibly affect server and P2P programs that need to open many outbound connections at the same time.

The solution that I’ve always been using is LvlLord’s Event ID 4226 Patcher (4226 fix) to patch the TCPIP.SYS file which increases the limited of half-open (incomplete outbound) TCP connection from 10 to 50. It works well except that whenever Windows released any hotfixes that updates TCPIP.SYS, I have to repatch the file all over again. Other than that, increasing half-open TCP connection does allows you to spread the worm faster if your computer is infected by one.

The best solution I’d say a tool which I recently stumbled on called TCP-Z (No it has nothing to do with the popular CPU-Z) which can release the power of your network, download faster, and more task can be run at the same time.

I say that TCP-Z is good because there is an option to modify the limited of half-open (incomplete outbound) TCP connection by patching the memory. If you want to start P2P download via BitTorrent, just run TCP-Z, increase the half-open TCP connection and start downloading. When you shutdown the computer and restart the next time, the previously increased TCP connections will be reset to default which is 10. The memory patching takes effect immediately without rebooting the computer and doesn’t modify any system files.

TCP-Z Event ID 4226 Patcher

Other than that, TCP-Z shows number of established connections, half open connections, Create depth, download/upload speed in real-time. It will also show the number of warnings events in per-minute, which TCP half open connection overload.

There are two methods to use TCP-Z. First is to manually run TCPZ.exe and go to Patch tab and change the settings there. Another way is to install TCP half open limited patcher in virtual device mode. Go to VirtualDevice folder inside TCPZ and run TCPZ_Setup-x86.exe if you’re running Windows 32bit or TCPZ_Setup-x64.exe if running Windows 64bit. You can then change the TCP limit from Device Manager > TCPZ Driver > TCP Half Open Limited Patcher (TCP-Z).

TCPZ Device Manager

TCP-Z works on Windows XP SP2 & SP3/2003/2008/Vista SP1 & SP2/Windows 7, all 32bit (x86) / 64bit (x64). It does what it supposed to and most importantly it is free and portable. Since this tool is capable of patching memory and system file TCPIP.SYS, your firewall or antivirus might find that this tool as a threat. Rest assured that it is definitely safe from virus if you downloaded it from the official TCP-Z website. Since I can’t get full download speed from RapidShare, I am back to using BitTorrent and TCP-Z is really a gem!

[ Download TCP-Z ]

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