DOCUMENT:Q167040 TITLE :PPTP Performance Update for Windows NT 4.0 Release Notes PRODUCT :Microsoft Windows NT PROD/VER:4.0 OPER/SYS:WINDOWS KEYWORD :kbfix4.00 kbfile --------------------------------------------------------------------------- The information in this article applies to the following: - Microsoft Windows NT Server version 4.0 - Microsoft Windows NT Workstation version 4.0 --------------------------------------------------------------------------- SUMMARY ======= This article contains a copy of the Point to Point Tunneling Protocol (PPTP) Performance Update for Microsoft Windows NT Server and Workstation version 4.0 Release Notes. The PPTP Performance Update has been replaced by the PPTP Performance and Security Upgrade for WinNT 4.0. The latest version is available at: ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/ hotfixes-postSP3/pptp3-fix/ NOTE: The above link is one path; it has been wrapped for readability. US and Canadian customers can download the 128-bit version of this hotfix from the following web page: http://mssecure.www.conxion.com/cgi-bin/ntitar.pl You can find the original version at the following Microsoft ftp site: ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/ hotfixes-postSP3/archive/pptp2-fix/ NOTE: The above link is one path; it has been wrapped for readability. WARNING: If you install the original (archived) version of this hotfix AFTER you apply the later version, your system may become unusable. Microsoft does not recommend you install the original hotfix after applying the later version. MORE INFORMATION ================ Point to Point Tunneling Protocol (PPTP) Performance Update for Microsoft Windows NT 4.0 Server and Workstation Release Notes Please use this document to address questions which may arise during the installation of this PPTP Update for Microsoft Windows NT 4.0 Server and Workstation. ---------------------------------------------------------------------- Contents - Information on Installation - New features added in this Update - Other issues addressed in this Update ---------------------------------------------------------------------- Information on Installation --------------------------- Microsoft has released a PPTP Performance Update for the Windows NT Workstation and Server version 4.0. We have made refinements to current Windows PPTP client and server communication technologies that significantly improve the performance of secure PPTP connections via the Internet. This update should be applied to both Windows NT 4.0 Servers and Workstations. You must have Service Pack 3 for Windows NT 4.0 installed before applying this update. Windows NT 4.0 Servers running Routing and Remote Access Service (RRAS) must first apply this Windows NT PPTP Update followed by the RRAS Hotfix 2.0. This update is packaged in an auto-install format. Copy the Update to a temporary directory, and double-click the executable name or type the executable name "pptpfixi.exe" for x86 or "pptpfixa.exe" for alpha (without quotation marks) at a command prompt to install. The files can also be extracted from the Update without installing them. To do this, copy the Update to a temporary directory, and type pptpfixi/x or pptpfixa/x at a command prompt. After extracting the files, the Update can be installed by typing hotfix at a command prompt. To uninstall this update, type "HOTFIX -Y" (without quotation marks) from the directory you copied the files to. Output of "HOTFIX -?": HOTFIX [-y] [-f] [-n] [-z] [-q] [-m] [-l] -y Perform uninstall (only with -m or -q) -f Force apps closed at shutdown -n Do not create uninstall directory -z Do not reboot when update completes -q Quiet or Unattended mode with no user interface -m Unattended mode with user interface -l List installed hotfixes RAS Servers that terminate compulsory PPTP connections from an FEP (Front End Processor) must disable historyless compression/encryption in order for legacy Windows 95 clients to receive data properly. An FEP is a dial-up server which can create a PPTP tunnel on behalf of its dial-up clients. This feature is available from several Access Server vendors, including Compaq (Microcom), Ascend, and 3com. The value to set in the registry to enable/disable historyless encryption/compression is: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NdisWan \Parameters Historyless: REG_DWORD: 0 - Disabled REG_DWORD: 1 - Enabled [default] New Features Added in this Update --------------------------------- PPTP Performance Issues Addressed in this Update: - A new historyless mode for encryption and compression over PPTP connections has been enabled in this update. This new mode solves performance problems encountered using PPTP in high latency networks or networks that experience significant packet loss. This upgrade is fully compatible with legacy PPTP systems. However, in order to negotiate historyless mode, both the PPTP client and server must support it. If either client or server refuses the new mode, normal MPPE compression and encryption will be negotiated. To experience the full benefit of the PPTP performance update, this Update must be installed on both Windows NT clients and servers. A corresponding release Microsoft Dial-Up Networking 1.3 is available for Windows 95 clients. - The default PPTP receive window size was increased to 16. - The window between the NDISWAN driver and the PPTP driver was increased. - The PPTP frame size defaults to 1400 bytes to avoid packet fragmentation. This was fixed in an earlier hotfix, and is also included in this update. It is documented at http://support.microsoft.com/support/kb/articles/q162/2/30.asp Other Issues Addressed in this Update ------------------------------------- Remote Access Service and PPTP Issues: - PPTP server responsiveness has been improved during the time period right after termination of multiple PPTP connections. - Corrected a problem in the PPTP server in which an improperly configured "start session" in the packet header could disable a PPTP server. It is documented at http://support.microsoft.com/support/kb/articles/q179/1/07.asp - Improved integrity of session encryption in MPPE by removing predictability of successive packet following an encryption or compression reset. - Corrected a user interface issue where, under certain situations, a RAS/PPTP server could allow a client to connect with no data encryption even though the administrator was under the impression that the server was configured to require data encryption. It is documented at http://support.microsoft.com/support/kb/articles/q177/6/70.asp - Updated MSCHAP to disable sending the LM hash when client set to "require" 128-bit encryption. Other NT Issues Addressed in this Update ---------------------------------------- - This release includes an enhancement to TCP/IP which will improve the performance of TCP-based applications over high latency networks, such as the Internet. 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