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The SLIP/PPP Route

Step by Step: How to Set Up RAS for Windows NT

One of the most practical and economical connections to the Internet is to dial in to an Internet Access Provider (IAP) using either the Serial-Line Internet Protocol (SLIP) or the Point-to-Point Protocol (PPP). If you plan to use one of these methods, you'll probably want to install a Web browser so you can access the full range of graphical and multimedia presentation available on the World Wide Web. However, to take advantage of these features, you must also install and configure the Remote Access Service (RAS) for Windows NT Workstation/Server 3.5.

Sign Up with an IAP
SLIP/PPP: Sign up for either a PPP or SLIP dial-in account with a local IAP. Other IAPs are available in lists on the Internet, but you have to be on it to get them.

  • Your IAP should provide you with the following information--ask to have it in writing, if possible.
  • Internet access phone number (for your modem to dial)
  • Type of account--SLIP or PPP (preferable)
  • SLIP/PPP logon username/password (If you have a shell account where you dial in through a terminal emulator and log on to the IAP's host, the username/password for SLIP/PPP may be different. To use a shell account and SLIP/PPP, you may need a different username/password for each type of access.)
  • Your IP address (not required if your IAP uses dynamic IP addresses)
  • Your subnet mask ( is typical.)
  • Your computer host name (you can request a special name.)
  • The domain name (usually your IAP's unless you request your own; a fee may be charged if you do.)
  • Default gateway IP address (the address of the system you connect to)
  • Primary Domain Name Service (DNS) IP address (the primary name server you use for Internet access)
  • Backup DNS IP address (the backup name server)
  • An example login script for PPP or SLIP access (You may have to respond to a host prompt or issue a command after the login.)
  • Whether Van Jacobsen (VJ) header compression should be on or off

Install and Configure RAS
SLIP/PPP: After arranging for Internet service, it's time to install and configure the RAS software. (If you have not already installed network support, the system will ask if you want to install it. Base network support must be installed to run RAS.)

Look in the Installed Network Software list to see if TCP/IP or RAS support is installed. If so, remove the TCP/IP protocol and reboot the system. Then, confirm that NetBIOS Interface is in the list. If not, install it and reboot before continuing.

SLIP only: If you plan to use SLIP, MS Loopback Adapter must be installed. If it's not in the Installed Adapter Cards box, click on Add Adapter to add it.

SLIP/PPP: Next, install and configure RAS. The Add Network dialog box contains the default path to your NT distribution files.

If you have an external modem, connect it to the proper COM port with a serial cable. Then click on OK to start automatic detection of your modem. After about a minute, a message indicates which modem the system found.

Click on Continue to confirm that NT has properly detected the modem and the correct COM port. The RAS Setup box displays the progress of the install. If a warning appears about the automatic restoration of network connections, click on OK to bypass it.

If the system does not properly detect your modem, obtain the latest version of the Microsoft Windows NT Hardware Compatibility list and confirm that your specific modem model is listed there. If necessary, you can create a custom modem.inf entry for a non-supported modem; refer to the Windows NT 3.5 Resource Kit.

The system highlights the detected modem type and COM port in the Configure Port box. Under Configuration, select Dial out only in the Port Usage section. In the RAS Setup, select Disable automatic restoration of network connections at logon. Open the Network Configuration box and select TCP/IP (and deselect NetBEUI and IPX). Confirm the path to your NT distribution files, and click on OK to install the TCP/IP-related files.

When you return to the RAS Setup, reconfirm the path to your distribution files. Then, wait for NT to complete the installation of the RAS software, creation of the RAS program group, and installation of the RAS icons. When you return to Network Settings, click on OK to finalize it. It's okay if you receive a warning message about NetBEUI not being installed. Simply bypass it and reboot the system.

Configure TCP/IP
SLIP/PPP: Open the Network control panel item, select the TCP/IP protocol, and click on Configure.

PPP only: The TCP/IP Configuration box should appear (see Screen 1). Click on DNS and configure your host name and the domain name you will be using--normally your IAP's domain name. If you already have TCP/IP host and domain names defined for your local LAN, you must change them to access the Internet--NT supports only one host name and domain name at a time per system. Unfortunately, when they are configured for Internet access, you cannot communicate on your local TCP/IP network.

You don't need to select a particular adapter to configure the host and domain names; in fact, you don't need to have an adapter installed at all to implement PPP. The following fields will be blank: IP Address, Subnet Mask, Default Gateway, Primary WINS Server, and Secondary WINS Server. Under Advanced, deselect Enable DNS for Windows Name Resolution and deselect Enable LMHOSTS Lookup.

SLIP only: The TCP/IP Configuration box should appear (see Screen 2). Install MS Loopback Adapter from the Network Settings box. Click on OK to bypass the 802 option, then complete the binding and installation of this adapter. The TCP/IP Configuration box reappears so you can configure an IP address for your Internet connection. Select MS Loopback Adapter, and configure the IP address as follows:

  • If your IAP assigns you a specific IP address, enter that address in the box.
  • If your IAP uses dynamic IP addresses, you have to make up a dummy IP address. You must enter it before you can exit this screen. Ask your IAP for assistance in picking a dummy address. (You can use any of the IP addresses from the pool of dynamically assigned SLIP IP addresses.)
  • When you connect, your IAP automatically assigns the actual IP address.

Next, enter a subnet mask into its box. In most cases the mask value should be "' Then, enter the IP address for your IAP's default gateway into the Default Gateway box. Leave Primary WINS Server and Secondary WINS Server blank.

SLIP/PPP: From the TCP/IP Configuration box, click on DNS to access the DNS Configuration box (see Screen 3). Enter the Host Name and Domain Name information you received from your IAP.

PPP only: Leave DNS Search Order blank.

SLIP only: Enter the IP address for your IAP's primary DNS in the DNS Search Order box. You can also enter the IP address for a secondary DNS system (if you have one).

SLIP/PPP: The TCP/IP Configuration box reappears. Click on Advanced to invoke the Advanced Microsoft TCP/IP Configuration box (see Screen 4).

SLIP only: Confirm that Adapter equals MS Loopback Adapter, and that your IP Address, Subnet Mask, and Default Gateway are correct.

SLIP/PPP: Under Windows Networking Parameters, make sure that Enable DNS for Windows Name Resolution and Enable LMHOSTS Lookup are not selected (the system uses these settings if you dial in to RAS). Also confirm that Enable WINS Proxy Agent is not selected and that Scope ID is blank. Click on OK to confirm these settings and return to the TCP/IP Configuration box.

PPP only: You don't need to put anything in the main box to enable PPP dial-out.

SLIP only: Click on OK, and then on Yes to bypass the warning message about the empty Primary WINS address. Then click on OK in Network Settings to complete the final binding of TCP/IP protocol settings to MS Loopback Adapter.

Add Phone Book Entry
SLIP/PPP: Restart your system, log in, open the RAS program group, and double-click on the Remote Access icon to start the RAS program. Since your phone book is blank, the system asks if you want to add a new phone book entry. Click on OK; the Add Phone Book Entry box appears.

Type the entry name, the phone number, and (optionally) the description for your Internet connection. The entry name can be the name of your IAP; the phone number should be the one for the server. Click on Advanced to unfold the box. In the expanded area, deselect Authenticate using current user name and password and confirm that the correct Port is selected for the modem.

Next, go to the Modem Settings box, which lists the selected Modem at the top. Set the Initial speed (bps) for 14.4K internal modems to 38400 and for 28.8K V.34/V.FAST modems to 57600. If you are using an external modem and don't have a 16550 UART-based enhanced serial card, you must limit the baud rate selection to 19200 or less for reliable communications.

I recommend that you use an enhanced serial card with 16550 UARTs if you are using an external 28.8K modem. (You can use the Event Viewer under Administrative Tools to look for a source event labeled serial if the message reads as follows: "While validating that com(1-4) was really a serial port, a FIFO was detected. The FIFO will be used.' This message indicates that NT detected a 16550 UART for that particular COM port.) Also, make sure that the following options are selected: Enable hardware flow control, Enable modem error control, and Enable modem compression. Then, click on OK to confirm the modem settings and return to the Add Phone Book Entry box. Open the Network Protocol Settings box.

PPP only: Click on PPP. Make sure that only TCP/IP and Request LCP extensions (RFC 1570) are selected. (LCP or Link Control Protocol is used to establish, configure, and test the PPP data-link connection.) Click on TCP/IP Settings to access the PPP TCP/IP Settings box (see Screen 5). To assign your IP address:

  • If you are using dynamic IP addressing, your IAP will assign an IP address at connect time. In this case, check the Server assigned IP address box.
  • If you are not using dynamic IP addressing, you must assign the address. Check Require specific IP address, and enter your assigned IP address. Then, check Use specific name server addresses, and enter the IP address for your IAP's primary DNS in DNS. You can also enter an optional backup DNS system (in case your system cannot contact the primary system) in DNS backup.

Leave WINS and WINS backup set to zeroes. Select Use default gateway on the remote network. If your IAP supports PPP compression, also enable Use VJ header compression. Return to Add Phone Book Entry, click on Security, and check Accept any authentication including clear text in Security Settings. Under Terminal or Script, set Before dialing to none and After dialing to Terminal.

SLIP only: Click on Force header compression and Use default gateway on the remote network. Leave frame size set to the default of 1006 unless your IAP tells you to use a different SLIP frame size. Return to the Add Phone Book Entry box. Next, click on Security and check Use clear text Terminal login only. Under Terminal or Script, set Before dialing to none and After dialing to Terminal.

SLIP/PPP: Confirm all windows. The information you have entered is stored in a file named rasphone.pbk in the \winnt35\system32\ras directory.

Dial In to IAP
SLIP/PPP: To dial in to your IAP's server, locate the Remote Access icon in the Remote Access program group and double-click on it. The Remote Access window appears (see Screen 6). Highlight the entry name you created earlier, and click on Dial.

PPP only: If your IAP requires PAP (Password Authentication Protocol), enter the username/password for your PPP account in the Authentication box, but leave the domain information blank (it only applies for dial-in access to RAS servers). Only PPP servers requiring PAP use this username/password. (PAP provides a simple way for the NT client to establish its identity with the remote PPP server; it involves an exchange of username/password information. After the initial link is established, the username/ password is sent to the server until the request is authenticated or the connection is terminated.)

If your IAP does not use PAP, you can leave the username, password, and domain blank. Click on OK.

SLIP/PPP: A Connect to Providername box appears. A series of messages, such as Opening com port, Dialing nnn-nnnn, and Postconnecting using terminal, also appear. When the connection is established, an After Dial Terminal screen appears. Simply follow the login instructions furnished by your IAP.

PPP only: When you see the command prompt, type PPP, and press enter. Click on Done to complete the connection.

SLIP only: When you see the command prompt from the remote system, type SLIP and press enter. Note the IP address echoed by the remote system, and click on Done. After the second SLIP Login Terminal screen appears, type the dynamically assigned IP address (as echoed by the remote system) into the white box located in the lower right-hand corner of the screen. Click on Done.

Explore … Then Hang Up

With your connection established, you can minimize the RAS box and check out the functionality of your Internet connection. When you have finished, restore the Remote Access box, and click on Hang Up to terminate the link.


Troubleshooting Tips
If your SLIP/PPP connection has worked as expected, congratulations are in order. However, if you have encountered any difficulties, the following tips may help.
For both SLIP and PPP connections:
  • Verify that you entered the correct host name and domain name.
  • Verify that you entered the correct IP address for your system if you are using a specific IP address assignment. If you are using a dynamic IP address assignment, get an IP address from your IAP and try that specific address.
  • Verify the IP addresses you defined for your DNS systems.
For a PPP connection:
  • Change the setting for the VJ header compression option.
  • Change the setting for the Request LCP extensions option.
For a SLIP connection:
  • Change the setting for the Force header compression option.

For additional troubleshooting suggestions, see the Help information in the RAS program group and the Windows NT 3.5 Resource Kit.

IAPs Galore

US & International Phone
ANS 800-456-8267, 703-758-7700
Delphi Internet Services Corp 800-695-4005
Evergreen Internet, Inc 602-926-4500
Global Enterprise Services 800-358-4437, 804-229-4484
Information Access Technologies, Inc 510-704-0160
Primenet 800-463-8386, 602-395-1010
PSINet, Inc. 800-827-7482, 703-709-0300, 703-904-4100
SprintLink (US Only) 800-817-7755
UUNET Technologies, Inc 800-488-6384, 703-204-8000

One source of information on localized IAPs both in the US and internationally is Connecting to the Internet, A Buyer's Guide by Susan Estrada (O'Reilly & Associates, Inc., 1993).

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