How Can I Harden the TCP/IP Stack in Windows Server 2008? [duplicate]
They re-wrote the TCP/IP stack in Vista/2008 and included many security related changes.
You may be interested in reading the "Next Generation TCP/IP Stack" document from Microsoft as it contains links to the new registry settings, enhancements & security protections and others.
Check out the DISA / NSA Windows 2008 Server Security and Technical Implementation Guide (STIG) here (Scroll down for Windows guides): DISA IASE Site
The STIG has a number of security tweeks and registry changes designed to harden your network stack (and local machine in general).