communication between applications that would otherwise have problems communicating over a NAT. The IPv6 protocol for Windows Server 2008 and Windows Vista supports Teredo as a Teredo client and a Teredo host-specific relay.

For more information, see Chapter 14, “Teredo.”

PortProxy

PortProxy is a component of the IPv6 protocol for Windows Server 2008 and Windows Vista that functions as a TCP proxy to facilitate the communication between nodes or applications that cannot connect using a common Internet layer protocol (IPv4 or IPv6). By using PortProxy, IPv6-only nodes or applications can communicate with IPv4-only nodes or applications and vice versa.

For more information, see Chapter 11.

Application Support

Windows Server 2008 includes full support for operation over IPv6 in all of its included networking applications and services, except for the File Transfer Protocol (FTP) Publishing service and the Simple Mail Transfer Protocol (SMTP) Server service in Internet Information Services (IIS). The SMTP feature of Microsoft Exchange Server 2007 with Service Pack 1 includes an IPv6-capable SMTP service. Windows Vista includes full support for operation over IPv6 in all its included networking applications and services except the File Transfer Protocol (FTP) Publishing service in Internet Information Services (IIS).

With the exception of the FTP Publishing and SMTP Server services in IIS, you can create an IPv6-only network and perform all the Windows-based infrastructure and productivity services provided with Windows Server 2008 and Windows Vista, including the following:

■Active Directory domain services

■Web services

■Certificate services

■File and printer sharing

■Windows Media Services

Application Programming Interfaces

Windows Server 2008 and Windows Vista include IPv6 support for the following application programming interfaces (APIs):

■Windows Sockets

■Winsock Kernel

28Understanding IPv6, Second Edition

■Remote Procedure Call

■Internet Protocol Helper

■Win32 Internet Extensions

■.NET Framework

■Windows Filtering Platform

Windows Sockets

Windows Sockets (Winsock) is an API based on the familiar “socket” interface from the University of California at Berkeley. It includes a set of extensions designed to take advantage of the message-driven nature of Microsoft Windows. Version 1.1 of the Windows Sockets specification was released in January 1993, and version 2.2.0 was published in May 1996.

The Microsoft Windows implementation of sockets, Winsock, is designed to run efficiently on Windows operating systems while maintaining compatibility with the Berkeley Software Distribution (BSD) standard, known as Berkeley Sockets. With Winsock, programmers can create advanced Internet, intranet, and other network-capable applications to transmit application data across the wire, independent of the network protocol being used.

Winsock for Windows Server 2008 and Windows Vista has been enhanced to include IPv6 support as specified in RFC 3493, “Basic Socket Interface Extensions for IPv6” (with some exceptions), and portions of RFC 3542, “Advanced Sockets API for IPv6.” For the details of Windows Sockets support for IPv6, see Appendix B, “Windows Sockets Changes for IPv6.”

Winsock Kernel

Winsock Kernel (WSK) is a new transport-independent kernel-mode API. Using WSK, kernelmode software modules such as third-party drivers can perform network communication using socket-like programming semantics similar to those supported in user-mode Winsock. WSK was designed to provide an easy-to-use interface for kernel-mode developers. WSK supports both IPv4-based and IPv6-based connectivity for WSK-based software modules.

Remote Procedure Call

Remote procedure call (RPC) is an API that is used for creating distributed client/server programs. The RPC run-time stubs and libraries manage most of the details relating to network protocols and communication. RPC functions are used to forward application function calls to a remote system across the network. The RPC components in Windows Server 2008 and Windows Vista are IPv6-enabled. The RPC components have been modified to use the updated Winsock functions, which allows RPC to work over both IPv4 and IPv6.

IP Helper

Internet Protocol Helper (IP Helper) is an API that assists in the administration of the network configuration of the local computer. You can use IP Helper to programmatically retrieve information about the network configuration of the local computer and to modify that configuration. IP Helper also provides notification mechanisms to ensure that an application is notified when certain aspects of the network configuration change on the local computer.

IP Helper in Windows Server 2008 and Windows Vista has been extended to allow management and configuration of IPv6 and its components. Some of the areas that are IPv6-enabled are the following:

■Retrieving information about network configuration, network adapters, interfaces, addresses, IPv6, ICMPv6, routing, TCP, and UDP

■Receiving notification of network events

Win32 Internet Extensions

The Win32 Internet Extensions (WinInet) is an API used for creating an Internet client application. An Internet client application is a program that accesses information from a network data source (server) using Internet protocols such as gopher, FTP, or HTTP. An Internet client application might access a server to retrieve data such as weather maps, stock prices, or newspaper headlines. The Internet client can access the server through an external network (the Internet) or an internal network (an intranet).

WinInet in Windows Server 2008 and Windows Vista has been extended to support IPv6. This allows Microsoft Internet Explorer to use WinInet to access IPv6-enabled Web sites and to use literal IPv6 addresses in URLs.

.NET Framework

The .NET Framework is the programming model of the .NET platform for building, deploying, and running Extensible Markup Language (XML) Web services and applications. It manages much of the plumbing, enabling developers to focus on writing the business logic code for their applications. The .NET Framework provided with Windows Server 2008 and Windows Vista is IPv6-enabled, allowing .NET Framework applications to operate over either IPv6 or IPv4.

Windows Filtering Platform

The Windows Filtering Platform (WFP) is new to Windows Server 2008 and Windows Vista. It provides APIs so that third-party independent software vendors (ISVs) can participate in the filtering decisions that take place at several layers in the TCP/IP protocol stack and throughout the operating system. WFP also integrates and provides support for new firewall features,