Knowledge Base

UDP Broadcast Issues with Service Pack 4

Article ID: 197511

Article Last Modified on 10/31/2006

Microsoft Windows NT Workstation 4.0 Developer Edition
Microsoft Windows NT Server 4.0 Standard Edition

This article was previously published under Q197511

SUMMARY

When you apply Service Pack 4 for Windows NT version 4.0, TCP/IP, Windows Sockets, and Simple TCP/IP services are modified to be resistant to attack. This modification may cause a loss of functionality in programs that use User Datagram Protocol (UDP) broadcasts.

MORE INFORMATION

Because of the security issues fixed in Service Pack 4, the default behavior of Winsock sockets has been changed. Sockets now receive broadcast datagrams such as UDP broadcasts only if they have been explicitly set to do so. Prior to these fixes, any program that issued a Recvfrom() call would receive broadcast datagrams.

Programs affected by this change should be modified to operate as expected with Windows NT 4.0 Service Pack 4 or later.

REFERENCES

Winsock supports a socket option (SO_BROADCAST) that can be set to allow the Recvfrom() call to pass broadcast datagrams to the program. The default setting for this option is "Off." More information about the SO_BROADCAST option and the functions used to set socket options is documented in the Platform Software Development Kit (SDK), which is available online at the following Microsoft Web site:

http://msdn.microsoft.com.

Additional query words: simptcp

Keywords: kbinfo KB197511