Recommended Settings For Windows Xp / 2000: Learn Latest Computer And Mobile Hacking Tricks

Windows 2000 & XP, unlike NT supports large windows as described in RFC1323 ( the ‘RcvWindow’ has a maximum value of 2**30 rather than 64K), and includes some other improvements over its predecessors you can use to speed up any TCP/IP transfers. , the descriptions and other options are added to provide you with better understanding and enable you to customize your settings.

All the following entries, unless otherwise noted should be placed in the Windows 2000/XP Registry under the key

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

TCPWindowSize

The value of TCP Window in the Windows 2000 Registry is DWORD, representing number of bytes, with range from 0 to 2^30. The recommended values (in red) optimize TCP for any high speed Internet connection and work best in most cases, however if you’d like to use a custom value follow these guidelines:

For best results, the TCPWindow should be a multiple of MSS (Maximum Segment Size). MSS is generally MTU - 40, where MTU (Maximum Transmission Unit) is the largest packet size that can be transmitted. MTU is usually 1500 (1492 for PPPoE connections). To determine the MTU value of your ISP, check out the Advanced Registry Editing section of our site.

There are three places in the Windows 2000 Registry where you can add the TCP Window parameter.

HKLM/SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
GlobalMaxTcpWindowSize=”256960″ (DWORD, number of bytes) Valid range is from MSS to 2^30. Add the value as a decimal. Note: For best results RWIN has to be a multiple of MSS lower than 65535 times a scale factor that’s a power of 2, i.e. 44 x 1460 = 64240 x 2^2 = 256960. If you choose to use a RWIN lower than 65535, you can simply make it multiple of MSS and turn scaling off (Tcp1323Opts=0)

HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
TcpWindowSize=”256960″ (DWORD, number of bytes) Valid range is from MSS to 2^30. Add the value as a decimal. TcpWindowSize can also exist under TcpipParametersInterface - if added at this location, it overrides the global setting for this particular . Note (10/20/00): Seems MS has found another bug in Windows 2000, the TCPWindowSize should be configured with the global setting (GlobalMaxTcpWindowsSize) rather than this one - Q263088

Note: For best results RWIN has to be a multiple of MSS lower than 65535 times a scale factor that’s a power of 2, i.e. 44 x 1460 = 64240 x 2^2 = 256960. If you choose to use a RWIN lower than 65535, you can simply make it multiple of MSS and turn scaling off (Tcp1323Opts=0)

Tcp1323Opts

Tcp1323Opts is a necessary setting in order to enable Large TCPWindow support as described in RFC 1323. Without this parameter, the TCPWindow is limited to 64K.

HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Tcp1323Opts=”1″ (DWORD, recommended setting is 1. The possible settings are 0 - Disable RFC 1323 options, 1 - Window scaling but no Timestamp options, 3 - Window scaling and Time stamp options.)

Note: Tcp1323Opts=”3″ might help in some cases where there is increased packet loss, however generally you’ll achieve better throughput with Tcp1323Opts=”1″, since Timestamps add 12 bytes to the header of each packet.

DefaultTTL

DefaultTTL determines the time in seconds and the number of hops a packet lives. While it does not directly affect speed, a larger value increases the amount of time it takes for a packet to be considered lost, discarded and retransmitted. A value that’s too small can cause packets to be unable to reach distant servers at all.

HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
DefaultTTL=”64″ (DWORD, recommended setting is 64. Other settings that are widely used are 128 and 32)

EnablePMTUDiscovery

When set to 1 (True), TCP attempts to discover MTU automatically over the path to a remote host. Setting this parameter to 0 causes MTU to default to 576 which reduces overall performance over high speed connections. Note that this setting is different than our Windows 9x recommendation.

HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
EnablePMTUDiscovery=”1″ (DWORD - boolean, valid settings are 0–>False and 1–>True. Many connections perform better with this entry at 1, however, if you prefer to set your upstream to send fixed 1500 packets, you might want to use 0 instead). When set at 1, establishing connections and initial transfer speed might slow down a bit, however you will get better throughput if somewhere in the path large packets need to be fragmented.

EnablePMTUBHDetect

Setting this parameter to 1 (True) enables “black hole” routers to be detected, however it also increases the maximum number of retransmissions for a given segment. In most cases you’d want to keep BHDetect to 0 (False).

HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
EnablePMTUBHDetect=”0″ (DWORD - boolean, valid settings are 0–>False and 1–>True. Recommended setting is 0)

SackOpts

This parameter controls whether or not SACK (Selective Acknowledgement) support is enabled, as specified in RFC 2018. SACK is especially important for connections using large TCP Window sizes.

HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
SackOpts=”1″ (DWORD - boolean, recommended setting is 1. Possible settings are 0 - No Sack options or 1 - Sack Option enabled).

TcpMaxDupAcks

This parameter determines the number of duplicate ACKs that must be received for the same sequence number of sent data before “fast retransmit” is triggered to resend the segment that has been dropped in transit.

HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
TcpMaxDupAcks=”2″ (DWORD - range 1-3, recommended setting is 2).

Patches

This Includes

1. sguide_tweak_2k.zip
Description: Generic patch for Windows XP and Windows 2000 (all versions). This patch will optimize your TCP/IP Registry settings for high speed Internet connections. To install, extract the .inf file first, then double-click (or right-click on filename and choose install from the pull-down menu) and reboot for changes to take effect.

http://www.speedguide.net/files/sguide_tweak_2k.zip

2.sguide_tweak_2k_pppoe.zip

Description: Generic patch for Windows XP/2000 and DSL connections using PPPoE. This patch will optimize your TCP/IP Registry settings for high speed Internet connections. It is specifically designed for PPPoE DSL connections. To install, extract the .inf file first, then double-click (or right-click on filename and choose install from the pull-down menu) and reboot for changes to take effect.

http://www.speedguide.net/files/sguide_tweak_2k_pppoe.zip

3. winxp_dnscache.zip

Description: Patch Windows 2k/XP not to cache failed DNS entries. By default, when a DNS lookup fails (due to temporary DNS problems), Windows still caches the unsuccessful DNS query, and in turn fails to connect to a host regardless of the fact that the DNS server might be able to handle your lookup seconds later. This patch fixes the problem by configuring the DNS client to continue sending queries to an unresponsive network. To install, save to your HD, unzip the .reg file, then double-click the filename.

Web Patches - faster loading of Web Pages

The following patch increases Web page loading speed, by doubling the number of possible concurrent open connections. For example, imagine a web page has 20 images and some text - in order for your browser to get all these files, it opens 2 or 4 concurrent connections, depending on the Web server. Increasing the number of open connections allows for faster retrieving of the data. Please note that the patch sets some values outside of the HTML specs. If you decide to install it, backup your Registry first. Changes will take effect after you reboot. Download the patch appropriate for your OS:

OS: Windows 9x/ME

http://www.speedguide.net/files/sg_webtweak_9x.zip

OS: Windows 2K/XP/2k3

http://www.speedguide.net/files/sg_webtweak_2k.zip

TCP OPTIMISER

Description: The TCP Optimizer is a free, easy Windows program that provides an intuitive interface for tuning and optimizing your Internet connection. Just download and run, there is no installaion required. The program makes it easy to find the best MTU and RWIN values, test latency and tweak all the important broadband related registry parameters. The Optimizer can be helpful with tuning any Internet connection type, from dialup to Gigabit+