Socket Programs May Not Connect to Server

• 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 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 ntsp kbbug4.00 kbfix4.00 nt4sp5fix
Version : winnt:4.0 SP4
Platform : winnt
Issue type : kbbug