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Q&A: Types Of Socket Applications Supported By Microsoft

This article was previously published under Q151210
This article has been archived. It is offered "as is" and will no longer be updated.
This article contains questions and answers regarding the different typesof socket application supported by MS-DOS and the Microsoft Windowsoperating system.
What is a socket application?

A socket interface was first provided with Berkeley UNIX (BSD) in theeighties. It was designed as a network interprocess communication (IPC)mechanism for the built-in TCP/IP. A socket defines a bi-directional endpoint for combination between processes.

A socket has three primary components:

   The interface to which it is bound   The port number to which it will send or receive data   The type of socket--either stream or datagram				

In TCP/IP, the interface is the IP address of the host. The port number isthe software process address. In IPX/SPX, the interface is the combinationof the IPX network ID and the MAC address of the network interface. Theport number is the software process address (IPX socket number).

A server application listens on a well-known port over all installednetwork interfaces. A client generally initiates communication from aspecific interface from any available port.

What is Windows Sockets?

The Windows Socket (WinSock) specification defines a network programminginterface for Microsoft Windows that is based on the Socket interfacepopularized in Berkeley Unix. The WinSock API is a library of functionsthat implement the Windows Socket specification. WinSock augments theBerkeley socket implementation by adding Windows-specific extensions tosupport the message-driven nature of Windows operating systems.

There are a few other proprietary windows socket APIs (WSOCKETS, andWIN_SOCK). For more information see the following article in theMicrosoft Knowledge Base:


These are not encouraged APIs and do NOT implement the Windows SocketsAPI standard.


WINSOCK.DLL is a dynamic-link library (DLL) that provides Windows Socketsversion 1.1 API for TCP/IP Windows Socket applications. WINSOCK.DLL isoffered in current version of all Microsoft TCP/IP stacks:

   MS-DOS TCP/IP for Lanman 2.2C   MS-DOS TCP/IP for Microsoft Network 3.0 Clients   Microsoft TCP/IP for Windows for Workgroups   Microsoft TCP/IP-32 for Windows for Workgroups   Microsoft TCP/IP for Windows NT 3.5x   Microsoft TCP/IP for Windows 95				

For additional information about Microsoft TCP/IP protocol comparison, seethe following article in the Microsoft Knowledge Base:

94069Microsoft TCP/IP Protocol Comparison and FAQ

What version of the WinSock specification does WINSOCK.DLL comply with?

Microsoft WINSOCK.DLL complies with Windows Socket Specification version1.1. Support for previous versions of the Sockets specification is notprovided. WINSOCK.DLL does not provide support for Raw Sockets(SOCK_RAW),DOS Sockets, or vendor-specific implementations.

For instruction about downloading the WinSock specification fromMicrosoft, see the following article in the Microsoft Knowledge base:

85965Microsoft Socket API Specification version

What is WSOCK32.DLL?

WSOCK32.DLL is a dynamic-link library (DLL) that provides Windows SocketsAPI for 32-bit TCP/IP Windows Socket applications and 32-bit IPX/SPXWindows Socket Applications. WSOCK32.DLL is offered in Windows NT and 95.

Can Microsoft WINSOCK.DLL be used with third-party TCP/IP stacks?

No. WINSOCK.DLL and WSOCK32.DLL will be provided by the vendor providingthe TCP/IP stack. The DLL and the protocol stack implementation cannot bemixed and matched with other TCP/IP and DLL implementations. For example,you cannot use WINSOCK.DLL provided by Microsoft with FTP's TCP/IP stack orvice versa.

What type of Socket applications are supported by MS-DOS TCP/IP stacks?

MS-DOS TCP/IP for Lanman 2.2c and Microsoft Network Clients 3.0 support DOSSocket application and WinSock 1.1 application. Sockets.exe in MS-DOS TCP/IP is a terminate-and-stay-resident (TSR) program; it allows MS-DOS socket applications to run if they've been written with the Microsoft TCP/IP Sockets Development Kit Version 1.0, using the DOS Socket Library (DOS_SOCK.LIB) available in the Development Kit. WSOCKETS.DLL is provided in Lanman 2.2 SDK to make Windows calls look as they do in MS-DOS.

While the 16-bit MS-DOS TCP SDK is still available (through Microsoft Developer Support), it is no longer supported by Microsoft and is not guaranteed to work. The user accepts full responsibility regarding the use of the SDK.

The SOCKETS.EXE and WSOCKETS.DLL do NOT implement the Windows Sockets APIstandard.

In order for a Windows Socket application to function with MS-DOS TCP/IP,SOCKETS.EXE must be loaded before Windows startup and WINSOCK.DLL mustexist in the application search path.

Is it possible to run a 32-bit Windows Socket application with Windows3.x?

Yes. Win32s 1.1 contains a thunking layer that converts 32-bit WindowsSockets calls (using WSOCK32.DLL) to 16-bit Windows Sockets calls (usingWINSOCK.DLL).

Does a Windows Sockets application work over any protocols other thanTCP/IP?

Yes. In Windows NT and 95, sockets support is also extended to IPX/SPX.Both 16-bit and 32-bit IPX/SPX Windows sockets are supported over NWLINK inWindows NT and 95.

Does MS Network Client 3.0 support MS-DOS/Windows IPX/SPX Socketapplications?

No. MS-DOS/Windows IPX/SPX Socket applications running in a Virtual machineof Windows 95 can be interfaced with NWLINK via WSOCK.VXD. WSOCK.VXDsupports 16-bit Windows Sockets application over 32-bit TCP/IP and IPX/SPXWindows Socket.

Article ID: 151210 - Last Review: 02/28/2014 08:03:25 - Revision: 3.1

Microsoft Windows NT Workstation 3.5, Microsoft Windows NT Workstation 3.51, Microsoft Windows NT Server 3.5, Microsoft Windows NT Server 3.51, Microsoft LAN Manager 4.2 Standard Edition, Microsoft TCP/IP for Windows for Workgroups 3.11b, Microsoft Windows for Workgroups 3.2, Microsoft Windows 95

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