DOCUMENT:Q228811 18-NOV-2000 [winnt] TITLE :Socket Programs May Not Connect to Server PRODUCT :Microsoft Windows NT PROD/VER:winnt:4.0 SP4 OPER/SYS: KEYWORDS:kbnetwork kbWinNT400sp5fix ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Server version 4.0 SP4 ------------------------------------------------------------------------------- SYMPTOMS ======== After you install Windows NT 4.0 Service Pack 4 on your computer running Windows NT, socket-based programs may stop responding (hang). A network trace may show that the TCP/IP packets may not be ordered in the proper sequence. CAUSE ===== This behavior is caused by a change in the calculations for random Initial Sequence Numbers (ISN) used in TCP/IP packets. As a result, an ISN may be generated that is less than the current ISN and, as a result, TCP/IP packets may be out of sequential order. RESOLUTION ========== To resolve this problem, obtain the latest service pack for Windows NT 4.0. 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 the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows NT version 4.0 Service Pack 5. MORE INFORMATION ================ For additional information about random Initial Sequence Numbers, please see the following article in the Microsoft Knowledge Base: Q192292 Unpredictable TCP Sequence Numbers in SP4 Additional query words: ====================================================================== Keywords : kbnetwork kbWinNT400sp5fix Technology : kbWinNTsearch kbWinNT400xsearch kbWinNTSsearch kbWinNTS400sp4 kbWinNTS400xsearch Version : winnt:4.0 SP4 Hardware : ALPHA x86 Issue type : kbbug Solution Type : kbfix ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2000.