--------------------------------------------------------------------------
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 Enterprise Edition version 4.0
--------------------------------------------------------------------------
SYMPTOMS
========
After receiving spoofed connection request (SYN) packets, Windows NT may
begin to operate slowly. After about one minute, Windows NT returns to
normal operation.
NOTE: This problem may occur with TCP/IP on other operating systems as
well.
CAUSE
=====
This behavior occurs due to "Land Attack". Land Attack sends SYN packets
with the same source and destination IP addresses and the same source and
destination ports to a host computer. This makes it appear as if the host
computer sent the packet to itself. Windows NT operates more slowly while
the host computer tries to respond to itself.
RESOLUTION
==========
To resolve this problem, obtain the following fix or wait for the next
Windows NT service pack.
This fix should have the following time stamp:
11/25/97 04:54p 143,472 Tcpip.sys (Intel)
11/25/97 04:52p 263,375 Tcpip.sys (Alpha)
This hotfix has been posted to the following Internet location:
ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/
hotfixes-postSP3/land-fix/
NOTE: This fix supercedes the ICMP-fix, OOB-fix, and the Simptcp-fix
hotfixes.
STATUS
======
Microsoft has confirmed this to be a problem in Windows NT version 4.0.
A supported fix is now available, but has not been fully regression-tested
and should be applied only to systems experiencing this specific problem.
Unless you are severely impacted by this specific problem, Microsoft
recommends that you wait for the next Service Pack that contains this fix.
Contact Microsoft Technical Support for more information.
MORE INFORMATION
================
For information on the hotfix for Windows 95, please see the following
article in the Microsoft Knowledge Base:
ARTICLE-ID: Q177539
TITLE : Windows 95 Stops Responding Because of Land Attack
Additional query words: 4.00 port 139
============================================================================
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.