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Q170998: Cannot Log in to Windows NT Domain Over Internet Connection

Article: Q170998
Product(s): Windows for Workgroups and Windows NT Networking Issues
Version(s): WINDOWS:95; winnt:3.5,3.51,4.0
Operating System(s): 
Keyword(s): kbnetwork win95 win98
Last Modified: 10-AUG-2001

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The information in this article applies to:

- Microsoft Windows 95 
- Microsoft Windows 98 
- Microsoft Windows NT Server versions 3.51, 4.0 
- Microsoft Windows NT Workstation versions 3.5, 3.51, 4.0 
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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
95/98-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 95/98, 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:

  Q161410 How to Set Up a Private Network Over the Internet Using PPTP

  Q154062 How to Set Up a Windows NT PPTP Client

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

  Q142027 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:

  Q143478 Stop 0A in TCPIP.SYS When Receiving Out Of Band (OOB) Data

  Q168747 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:

  Q139608 SMB Traffic During Windows NT Domain Logon

Additional query words: winnt

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Keywords          : kbnetwork win95 win98 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT351search kbWinNT350search kbWinNT400search kbWinNTW350 kbWinNTW350search kbWinNTW351search kbWinNTW351 kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbWinNTS351 kbWinNTS351search kbWin95search kbWin98search kbZNotKeyword3 kbWin98
Version           : WINDOWS:95; winnt:3.5,3.51,4.0
Issue type        : kbinfo

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