Tweaking maximum half-open connection limit in XP and Vista

Microsoft has set limits for number of concurrent TCP connection attemps in WIndows, in order to protect users from malicious bots, spyware etc. Normal users will not face any problems. But the p2p applications such as BitTorrent(uTorrent, BitComent, Azureus, etc), Limewire, eMule, Sopcast, TVants and some multiplayer games (mainly P2P games) may face some slow download and upload speed due to this limit.

Registry tweaks doesn't work. They set those limits in TCPIP.SYS and other system files which need to be patched. Following explains how to patch your Windows XP and Windows Vista versions.

Windows XP
Original Windows XP & XP SP1 doesn't have any limits. But since XP SP2, only 10 concurrent TCP connections are possible.
Each time your computer tries to establish more than 10 half-open connection, a system event will be logged in Windows. It looks something like this:
"EventID 4226: TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts"
Access the event viewer by Start / Control Panel / Administrative Tools / Event Viewer / System. Sort by Event and scroll down to 4226.

How to fix connection limit in windows xp sp2 and sp3?
It is very simple. First you download Event ID 4226 Patcher version 2.23d. Extract the contents and run ExID4226Patch.exe.

In default, it will set the limit to 50. But you can change the limit to any number you want. for eg: 1000.



Windows Vista
Windows Vista have different limit for different Vista edition. For eg, Home Basic has maximum limit of 2 and Vista Ultimate have maximum limit of 25 per second.

Go to Control Panel>Administrative Tools>Event Viewer. You could see "EventID 4226: TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts" under System log.


How to fix connection limit in vista?
Vista have enhanced security. So tweaking limit is not easy as in xp.

First you need to find out which version of tcpip.sys you have. Go to \Windows\System32\drivers folder, right click on tcpip.sys and select “Properties”, and the version info will be listed in “Details” pane.

Download the patch for your tcpip.sys version

• patch for ver 6.0.6000.16386 (32bit/64bit)
• Patch for ver 6.0.6000.20645 (32bit)
• Patch for ver 6.0.6000.16567 or 6.0.6000.20689 (32bit/64bit)
• Patch for ver 6.0.6000.16627 (32bit/64bit)
• Patch for ver6.0.6000.20752 (32bit/64bit)
• Patch for ver 6.0.60001.18000 (32bit/64bit)
• Patch for ver 6.0.60001.18063 or 6.0.6001.22167 (32bit/64bit)

Unpack and extract the content of the archive. Follow the instructions in the README.TXT file that comes with the patch. For running InstallPatch32.bat (for x86 system) or InstallPatch64.bat (for x64 system), administrator rights elevation required. Right click on command prompt(start>programs>accessories) and select "Run as Administrator". Execute the bat files using this command prompt.

IMPORTANT
Vista (32/64) requires all drivers to be digitally signed. It will fail to boot up or block driver from loading.

One way of to solve this issue is by pressing F8 during initial boot of the Windows Vista system, and then select Disable Driver Signature Enforcement in the “Advanced Boot Options” menu. However, you have to repetitively do the same process again and again on every system reboot.

But you can automate this process using ReadyDriver Plus. You can download it from here. It will ask for /BOOT path(choose drive which vista is installed). If you have dual boot, you need to choose number of keystrokes. For eg: if you have windows xp under windows vista in boot menu, you need to select 2 keystrokes.

Port Forwarding

Many of the broadband ISP(Internet Service Provider) provides you a router instead of modem. A Router is a device that forwards data packets along network. A broadband router connect LAN(Local Area Network) and ISP's network. Routers use headers and forwarding tables to determine the best path for forwarding the packets. If you have a LAN or having multiple computers which connect to internet then router is best.

Every devices on the internet has an unique IP address which helps to identify that device in internet. In a router based internet connections your PC will not be directly connected to internet like connections using modem. This will seriously affect Online multiplayer games and P2P applications(eg: Bit Torrent).

Port Forwarding(tunneling) is basically forwarding a port from one node to the other. This technique allows an outside user to access a certain port (in a LAN) through a NAT (Network Address Translation) enabled router.

Check whether your connection is router based or not?

• Go to Run ([Windows key]+R or Start->Run)
• Type "cmd" and press [Enter] (for 95, 98 & ME use "command")
• It will open Command prompt. In that, type "ipconfig" and press [Enter]
• If the IP Address(IPv4 Address for Vista) & Default Gateway are in 192.168.x.x range then you have router.

Setup static IP for your PC

• In Windows XP, go to Control Panel->Network Connections. In Windows Vista, go to Control Panel->Network and sharing center->Manage network connections
• Right click on your connection and choose properties. It will open Local Area Network Connnection properties.
• Click on Internet Protocol [TCP/IP](TCP/IPv4 for vista) and click on Properties button.
• If it is not set as Obtain IP Address automatically then your IP is static.
• Otherwise type ipconfig/all in command prompt and note information such as IP Address, Subnet mask, Default Gateway and DNS Adresses.
• Click on the Use following IP address and fill in all the boxes using those values and click Ok button.
  

Setting up Port forwarding
Different applications and games uses different ports. Setting up port forwarding is different for all routers.
Visit website http://portforward.com/routers.htm and choose your router model. It will guide you how to set up port forwarding in your router.

Summary of steps involved:

1. Open your router's configuration page in your browser. for eg: http://192.168.1.1/ which is same as your gateway ip address.
2. It will ask for usernam and password. For username:password try admin:admin or admin:password or ZXDSL:ZXDSL or root:root or both blank.
3. Look for the page like "Port forwarding" or "Virtual Servers" or "NAT Configuration".
4. Click on the Add button or link.
5. For Server IP use your computer's IP. For eg: 192.168.1.2. External and Internal port range are same values. For Single port, give same port value for start and end. If you are not sure about protocol, set up for both TCP & UDP.
6. After configuring, you need to restart router.

Ports
Some of Game ports are listed below. If you cannot find your application/game in this list then go to website http://findports.com/document.php?id=1095

Game	Port(s)	Protocol
Age of Empires Age of Empires Expansion: Rise of Rome Age of Empires II: the Age of Kings Age of Empires II Expansion: The Conquerers Age of Wonders	47624	TCP
	2300-2400	TCP, UDP
	6073	TCP
America's Army	1716	???
Asheron's Call Asherson's Call Dark Majesty	9000-9013	UDP
Baldur's Gate	47624	TCP
	2300-2399	TCP
	2300-2399	UDP
Battlezone 2	17770	UDP
	17771	TCP, UDP
	17772	UDP
Blizzard Battle.Net	4000	TCP, UDP
	6112-6119	TCP, UDP
Close Combat Close Combat: A Bridge Too Far Close Combat III: The Russian Front	47624	TCP
	2300-2400	TCP
	2300-2400	UDP
Close Combat IV Close Combat V	47624	TCP
	2300-2400	TCP
	2300-2400	UDP
Counter Strike	27030-27039	TCP
	1200	UDP
	27000-27015	UDP
Diablo Diablo II Diablo II: Lord of Destruction	4000	TCP, UDP
Dungeon Siege	80	TCP
	2300	UDP
	6073	UDP
	2302-2400	UDP
Empire Earth	33334	UDP
	33335	TCP
GameSpy Arcade	6667	TCP
	3783	TCP
	27900	TCP
	28900	TCP
	29900	TCP
	29901	TCP
Half-life	27015	TCP
Kali	2213 + 1 for each client	TCP
MechWarrior 4:Vengeance	6073	TCP
	2302-2400	UDP
	27999	TCP
	28000	TCP
	28805-28808	TCP
	9999	TCP
Microsoft DirectPlay4 DirectX7 Lobbyable App	47624	TCP
	2300-2400	TCP
	2300-2400	UDP
Microsoft DirectPlay8 DX8 Lobbyable App	6073	UDP
	2302-2400	UDP
Microsoft DirectX 7 CART Precision Racing, version 1.0 Combat Flight Simulator Flight Simulator MechCommander 2.0 Midtown Madness Monster Truck Madness Motocross Madness Urban Assault	47624	TCP
	2300-2400	TCP
	2300-2400	UDP
Neverwinter Nights	5120-5300	UDP
	6500	UDP
	27900	UDP
	28900	UDP
Quake 4	28004	UDP
	27950	UDP
Sacrifice	6073	UDP
	2302-2400	UDP
Star Wars: Galactic Battlegrounds	47624	TCP
	2300-2400	TCP
	2300-2400	UDP
Starcraft Starcraft: Brood War	4000	TCP
Unreal Tournament	7777	TCP, UDP
Warrock	5340	TCP
	5350	UDP
World of Warcraft	3723	TCP
	6112	TCP
	6881-6999	TCP
World War II Online	27015-27020	TCP
Microsoft Zone.com	6667	TCP
	28800-29000	TCP

DMZ
This is a feature included in some routers. A DMS allows router to forward all the ports to a single machine. If you are the only one who uses internet through that router then I recommend you to set up DMZ instead of port forwarding. It will make your router act like modem.
Setting up DMZ is very simple. First setup static IP for your PC. Then in the DMZ configuration on your router, give your computer's IP in the Server IP address box and click Save or Ok. After configuring, you need to restart router.