Microsoft KB Archive/107885

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Article ID: 107885

Article Last Modified on 12/14/2000


  • Microsoft Routing and Remote Access Service 1.1a

This article was previously published under Q107885


A Remote Access Service (RAS) for Windows NT 3.1 server MODEM.INF file will need modification in order to allow RAS for Windows for Workgroups 3.11 clients or RAS for Windows NT 3.1 clients to be successfully authenticated if an AT&T BNS 1000 security switch box (or similar device) is linked in line between the RAS server's serial port and its modem.

Configuration Diagram

RAS client---modem <---phone line---> modem---BNS1000---RAS server

This information does not apply to RAS 1.0, 1.1, nor 1.1a, because these versions do not include support for any kind of dialogue with a security host such as the AT&T BNS 1000 switch device.

NOTE: The AT&T BNS 1000 device has NOT been certified for use with RAS at the time this article was written (November 29, 1993) and Microsoft therefore does NOT support it at this time. However, the following modifications may be all that's needed to operate RAS with this device successfully.


If the following modifications to the RAS server's MODEM.INF file are not made, the RAS client user will initially be able to connect to the RAS server's modem, go into RAS' interactive Terminal mode and be successfully authenticated by the AT&T BNS 1000 security device, but then will be disconnected immediately after choosing Done in the Terminal mode.

In order for the RAS server to properly wait for the client signal and authenticate RAS callers, do the following:

  1. Stop the RAS server.
  2. Copy the [SD ACM400 w/ AT&T 3820] section in the MODEM.INF file to the of the file to create a new section.
  3. Give the newly created section a new section title, for example, [AT&T BNS 1000 switch] and remove all the comment lines below the section title that start with a semicolon.
  4. Remove all the following lines

           - macros(for example, "<speaker_on>=M1" and so on)
           - COMMAND_INIT
           - COMMAND_DIAL

    and then edit the rest of the section so it looks like this:

          [AT&T BNS 1000 switch]
  5. Save and close the MODEM.INF file.
  6. In the Control Panel window, choose the Network icon, and then select Remote Access Service in the Installed Network Software list. Choose Configure and reconfigure RAS to use the newly created section in the MODEM.INF file.
  7. Restart RAS on the server.

With this new MODEM.INF section, the RAS server will NOT attempt any initialization of a modem or other device, but will simply listen and then attempt to match the string "DIALIN_GATEWAY" with the information sent by the RAS client. The RAS client sends this string several times during the initial connection process which allows for a successful connection.

Additional query words: wfw wfwg prodnt

Keywords: kbnetwork KB107885