Cannot Log in to Windows NT Domain Over Internet connection

Last reviewed: December 30, 1997
Article ID: Q170998

The information in this article applies to:

Microsoft Windows 95
Microsoft Windows NT Server versions 3.1, 3.5, 3.51, 4.0
Microsoft Windows NT Workstation versions 3.1, 3.5, 3.51, 4.0

SUMMARY

If you are connected to the Internet through an Internet service provider (ISP), you may not be able to log in to a Windows NT Domain, or use Microsoft Networking functionality to connect to another Windows NT-based or Windows 95-based computer on the Internet. This may occur even though you may have been able to in the past.

MORE INFORMATION

A number of ISPs have disabled User Datagram Protocol (UDP) ports 137 and 138 and Transmission Control Protocol (TCP) port 139 on their routers to reduce network traffic and provide protection against out-of-band (OOB) data attacks on servers. Microsoft Networking components rely on these ports (especially TCP port 139) for NetBIOS communication.

If you could previously use Microsoft Networking components over the Internet but no longer can, contact your ISP to determine if UDP ports 137 or 138 or TCP port 139 has been disabled on the ISP's routers.

NOTE: This method of connecting to a Windows NT domain over the Internet is not a secure configuration and is not recommended by Microsoft. However, you can use the Point-to-Point Tunneling Protocol (PPTP) as an alternative method for communicating with your network over the Internet. PPTP is a networking technology that supports multiprotocol virtual private networks (VPNs), enabling remote users to access corporate networks securely across the Internet. Using PPTP, remote users can use Windows NT Workstation, Windows 95, and other point-to-point protocol (PPP)-enabled computers to dial into a local Internet service provider to connect securely to their corporate networks using the Internet.

REFERENCES

For more information about TCP ports, see the following RFC:

   RFC-1700: Internet Assigned Numbers

For additional information about PPTP, see the following articles in the Microsoft Knowledge Base:

   ARTICLE-ID: Q161410
   TITLE     : How to Set Up a Private Network Over the Internet Using
               PPTP

   ARTICLE-ID: Q154062
   TITLE     : Using PPTP Over a Non-PPTP Enabled Internet Provider

For additional information about problems connecting to computers running Microsoft Networking components over the Internet, see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q142027
   TITLE     : Troubleshooting NET USE Failure (When PING NetBIOS Name
               Works)

For additional information about out-of-band data, see the following articles in the Microsoft Knowledge Base:

   ARTICLE-ID: Q143478
   TITLE     : Stop 0A in TCPIP.SYS When Receiving Out Of Band (OOB) Data

   ARTICLE-ID: Q168747
   TITLE     : Update to Windows 95 TCP/IP to Address Out-of-Band Issue

For information about the types of network traffic created when you are using Microsoft Networking components (without PPTP), see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q139608
   TITLE     : SMB Traffic During Windows NT Domain Logon

Additional query words: 4.00 winnt
Keywords : win95 kbnetwork
Version : WinNT:3.1,3.5,3.51,4.0;WINDOWS:95
Platform : WINDOWS

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Last reviewed: December 30, 1997
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