Microsoft tcpip.sys hard limit removal

Yesterday I was diagnosing why my torrent server was having problems connecting to trackers through my vpn proxy, when I came across a piece of information I learned a year ago but had completely forgotten about. Since XP service pack 2, Microsoft have hard coded a limit into tcpip.sys, limiting the maximum simultaneous half-open (incomplete) outbound TCP connection attempts per second that the system can make. This was to protect the system from virus propagation and to stop DDOS attacks being launched from a compromised system. When the limit is hit, you get this in the systems event log :

EventID 4226: TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts

Windows XP SP2 has a limit of 10 maximum incomplete concurrent connection attempts per second while Vista depends on the version you have, Vista home Basic has maximum limit of 2 and Vista Ultimate is 25 per second.
Your normal user isn't going to have any problems with these limits, but when you have a torrent application and streaming as well you're going to hit it. I regularly have 12+ torrents seeding (fulfilling my civic duties to my private trackers), plus 5 - 6 downloading and seeding, add a Steam update and watch some internet TV and I am hitting the wall.

To remove the limit you need to patch tcpip.sys , this is easy with XP but with any Windows x64 OS you have to disable the driver signing integraty check, Vista also has ehanced security to get around. There are a few ways listed to do this around the internet, but the easiest by far is this patch.

The patch works for the following MS OS's :
Windows XP SP1(x64)/SP2(x86,x64)/SP3, Server 2003 SP1(x86)/SP2(x86,x64), Server 2008(x86,x64), Vista without SP(x86,x64) and with SP1(x86,x64)

It worked perfectly on my Vista Home Premium x64 system, but note this proviso from the site :

For Vista and Server 2008 users: Maybe sometime, after updating Windows or SP installation on a desktop will appear watermarks "Test mode". They can appear because in all versions of Vista and Server 2008, except Vista without SP(x86), there is the obligatory check of the signature of drivers, and the file tcpip.sys sign with test signature after patching. Most likely, to make it disappear will be necessary simply once again to patch tcpip.sys.

After making a few changes to utorrent and the limit fix, I no longer have any problems with trackers and the speed has increased :)

Update : Patch also works for Windows 7
Update 2 : This is also the reason for the "We're sorry, this video is no longer available" error from youtube.