Microsoft KB Archive/254930

= TCP Session with Server Never Closes =

PSS ID Number: 254930

Article Last Modified on 10/16/2002

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The information in this article applies to:


 * Microsoft Windows NT Server 4.0 Terminal Server Edition
 * Microsoft Windows NT Server 4.0
 * Microsoft Windows NT Workstation 4.0

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This article was previously published under Q254930



SYMPTOMS
A TCP session with a server may seem never to close, even though the client has requested to close the session. For example, a connection is established between two Windows NT-based computers. The server application quits, and the server sends a FIN request (which the network loses). The server state is now FIN_WAIT_1 or LAST_ACK and the client state is ESTABLISHED. The server will remain in the FIN_WAIT or last_ack state until a reboot is issued to restore incoming sessions. A Netmon trace will reveal that the server "resets" every incoming connection.



Windows NT Server and Workstation
A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Windows NT 4.0 service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English-language version of this fix should have the following file attributes or later:   Date        Time    Size     File name   Platform -  02/16/2000  08:01p  171,728  Tcpip.sys   Intel 02/16/2000 08:00p  305,840  Tcpip.sys   Alpha

Windows NT Server, Terminal Server Edition
A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Windows NT Server 4.0, Terminal Server Edition, service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English-language version of this fix should have the following file attributes or later:   Date        Time    Size     File name   Platform -  09/26/2000  04:48p  174,544  Tcpip.sys   Intel 09/26/2000 04:33p  311,024  Tcpip.sys   Alpha



Windows NT Server and Workstation
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

Windows NT Server, Terminal Server Edition
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.



MORE INFORMATION
When the client initiates the close of a session, it sends a FIN packet to the server. If the FIN packet is lost and never reaches the server, the client should retransmit the FIN packet when it does not receive an ACK response for the FIN packet. If the client does not retransmit the FIN packet, the server session does not close and orphans the session.

The server will remain in the FIN_WAIT or last_ack state until a reboot is issued to restore incoming sessions.

Example of a servers netstat -an:

TCP nj031fpsb01:nbsession NC031LLAB03.wcc.microsoft.com:1094 LAST_ACK

TCP nj031fpsb01:nbsession NC031LLAB03.wcc.microsoft.com:1096 LAST_ACK

TCP nj031fpsb01:nbsession NC031LLAB03.wcc.microsoft.com:1097 LAST_ACK

Refer to the Microsoft Developer Network (MSDN) for more information about FIN WAIT states and TCP state diagrams.

Additional query words: FIN_WAIT last_ack Filenet win2000hotnet netlogon 5719

Keywords: kbbug kbQFE KB254930

Technology: kbNTTermServ400 kbNTTermServSearch kbWinNT400search kbWinNTS400 kbWinNTS400search kbWinNTsearch kbWinNTSsearch kbWinNTW400 kbWinNTW400search kbWinNTWsearch

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