Point to Point Tunneling Protocol (PPTP) Performance Update for Windows NT 4.0 Release Notes

ID: Q167040

The information in this article applies to:

Microsoft Windows NT Workstation version 4.0
Microsoft Windows NT Server version 4.0
Microsoft Windows NT Server version 4.0, Terminal Server Edition

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 The PPTP Performance Update has been replaced by the PPTP Performance and Security Upgrade for WinNT 4.0. For your convenience, the English version of this post-SP3 hotfix has been posted to the following Internet location. However, Microsoft recommends that you install Windows NT 4.0 Service Pack 4 to correct this problem.

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. For more information, please see the following article in the Microsoft Knowledge Base:

ARTICLE-ID: Q168469
TITLE : RRAS Upgrade for WinNT Server 4.0 Hotfix Pack 2.0 Release Notes

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 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.

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 Windows 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.

Information in this document is subject to change without notice and is provided for informational purposes only. The entire risk of the use or results of the use of this document remains with the user, and Microsoft Corporation makes no warranties, either express or implied. The names of companies, products, people, characters, and/or data mentioned herein are fictitious and are in no way intended to represent any real individual, company, product, or event, unless otherwise noted. Complying with all applicable copyright laws is the responsibility of the user. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose, without the express written permission of Microsoft Corporation.

Microsoft may have patents, patent applications, trademarks, copyrights, or other intellectual property rights covering subject matter in this document. Except as expressly provided in any written license agreement from Microsoft, the furnishing of this document does not give you any license to these patents, trademarks, copyrights, or other intellectual property.

(c) 1998 Microsoft Corporation. All rights reserved.

Microsoft, MS-DOS, MS, Windows, Windows NT, are either registered trademarks or trademarks of Microsoft Corporation in the U.S.A. and/or other countries.

Other product and company names mentioned herein may be the trademarks of their respective owners.

RESOLUTION

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, please see the following article in the Microsoft Knowledge Base:

Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack

STATUS

Microsoft has confirmed this to be a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.


Keywords          : NT4SP4Fix kbbug4.00 kbfix4.00.sp4 
Version           : WinNT:4.0
Platform          : winnt 
Issue type        : kbbug

Last Reviewed: April 10, 1999