ChorusOS 4.0 Network Administration Guide

PPP on a Windows NT 4.0 Host

When PPP is used, Windows NT 4.0 allows the ChorusOS target to be fully connected to the enterprise LAN, making host-target communications possible with any network node, not only with the Windows NT 4.0 workstation.

PPP Connection Setup

This section explains how to set up the basic PPP connection between the host workstation and the ChorusOS target system.

Installing the Remote Access Service

Remote Access Service (RAS) and Dial-Up Networking (DUN) provide the basic serial line and modem connection services.

  1. Double-click the My Computer icon on the desktop.

  2. Double-click the Dial-Up Networking icon.

  3. Install Dial-Up Networking with ChorusOS Cable as the modem type. The ChorusOS Cable modem type is created during the initial installation of the host workstation environment.

Configuring the Serial Cable Connection
  1. Select Start | Settings | Control Panel.

  2. Double-click the Modems icon.

  3. Check Don't detect my modem; I will select it from a list., and then click the Next button.

  4. Select ChorusOS Cable from the list.

  5. Click the Properties... button.

  6. Select 9600 in the Maximum Speed combo box.

  7. Click the Connection tab.

  8. Click the Advanced... button.

  9. Check Record Log File.

  10. Confirm your selections, closing each dialog box by clicking the OK or Close button.

Configuring the Remote Access Service

Remote Access Service should be configured after you change the modem configuration.

  1. Select Start | Settings | Control Panel.

  2. Double-click the Network icon.

  3. Click the Services tab.

  4. Select Remote Access Services from the list.

  5. Click the Properties... button.

  6. Select COMx ChorusOS Serial Cable from the list.

  7. Click the Configure... button.

  8. Select Dial-out and receive calls in the Port Usage group, and then click the OK button.

  9. Click the Network... button.

  10. Make sure that only TCP/IP is selected in both the Dial-Out Protocols and Server Settings groups.

  11. Select Allow any authentication including clear text in the Encryption settings group.

  12. Click the Configure... button next to the TCP/IP checkbox.

  13. Select Entire network in the Allow remote TCP/IP clients to access group.

  14. Select Use static address pool.

  15. Enter the range of IP addresses that may be used for PPP.

    The range must contain at least two numbers, as the first number is used by the host workstation and the second by the ChorusOS target system. It is recommended that you use IP addresses on the same network as the Ethernet.

  16. Confirm your selections, closing each dialog box by clicking the OK or Close button.

    Windows NT 4.0 reconfigures its network settings and asks to reboot the system. Do not reboot the system yet.

Starting the Remote Access Service at Boot Time
  1. Select Start | Settings | Control Panel.

  2. Double-click the Services icon.

  3. Select Remote Access Server from the list.

  4. Click the Startup... button.

  5. Select Automatic in the Startup Type group.

  6. Click the OK button to close the Service dialog box.

  7. Click the Close button to close the Services dialog box.

Adjusting the Auto-Disconnect Timeout

By default, the Remote Access Service disconnects incoming connections after twenty minutes of inactivity, which may not be suitable with a ChorusOS system. You can modify the default behavior by editing the Registry.

  1. Select Start | Run.

  2. Enter regedit in the field provided to start the Registry Editor.

  3. Select

    in the Registry tree view.

  4. Change the value from 0x14 to 0x0.

  5. Disable the timeout.

  6. Exit the Registry Editor.

  7. Reboot the Windows NT 4.0 system.

Checking the Remote Access Service

After rebooting, Windows NT 4.0 listens for incoming PPP calls on the serial line. You can run the Remote Access Admin administration tool to see the state of the port.

  1. Select Start|Programs|Administrative Tools (Common)|Remote Access Admin to start the application.

  2. If Remote Access Service is not started, select Server | Start Remote Access Service....


The Windows NT 4.0 workstation PPP host requires that the client provide a valid username and password in order to connect. Both the username and password must be authorized for dial-in access in the Windows NT 4.0 user database.

Currently, the only authentication protocol shared by both ChorusOS systems and Windows NT 4.0 is the plain text Password Authentication Protocol (PAP). Therefore, you must select PAP for logging in. The username and password are the same as the ones used for logging in to the system.

Enabling Automated Target-to-Host Connections

In order to allow automated connections of diskless ChorusOS systems to the Windows NT 4.0 host at boot time, pppd supports a ChorusOS specific option, userpass username password, and its functional equivalent +ua filename, which makes it possible to obtain the same information from a file.

  1. Edit the options file to negotiate PAP, rather than CHAP authentication:

    # refuse CHAP authentication and require PAP
  2. Edit the pap.scr file to include the username and password needed for authentication:

    # pap.scr example
    # username * password
    myuser	* pa55word
Granting Dial-In Permission on the Host

Use the User Manager to authorize user to access the host workstation.

  1. Select Start|Programs|Administrative Tools (Common)|User Manager.

  2. Double-click user in the Username list.

  3. Click the Dialin button.

  4. Select Grant dialin permission to user.

  5. Confirm your selections, closing each dialog box by clicking the OK button.

Troubleshooting the PPP Connection

The following detailed logs can help you solve connection problems.


The modem log traces what happens during the modem connection before PPP communications are established. The modem log is enabled when you select Record Log File as part of the modem configuration procedure.


The PPP log traces setup of PPP communications. The PPP log must be explicitly enabled in the Registry, which you can do using the Registry Editor utility.

To start Registry Editor, select Start | Run, and then run regedit.

To enable the PPP log, set the

key to 1.

Addressing and Routing

On the Host

In order to make the ChorusOS system visible on the local Ethernet network, you must enable routing on the host workstation.

  1. Select Start | Settings | Control Panel.

  2. Double-click the Networks icon.

  3. Click the Protocols tab.

  4. Select TCP/IP Protocol from the list.

  5. Click the Properties... button.

  6. Click the Routing tab.

  7. Check Enable IP Forwarding.

  8. Confirm your selections, closing each dialog box by clicking the OK button.

  9. Reboot the host system.

On the ChorusOS Target

In order to route target IP traffic through the host workstation, you must add a default route to the IP address of the Windows NT 4.0 system after the connection from the target has been set up using the defaultroute option with pppd.

    Use the route command to enable a default route:

    $ rsh target route add default IP_address
    where IP_address is the IP address to which IP traffic is routed by default.

    Note -

    You can remove existing default routes using the delete option with the route command:

    $ rsh target route delete default IP_address

Sharing IP Addresses with the LAN

When you specify a subset of the addresses used on the local area network for serial line connections between the host workstation and one or more target systems, Windows NT 4.0 activates proxy-ARP for the connected serial clients automatically and behaves like a bridge. Windows NT 4.0 makes it possible, by default, to reach the PPP client from other systems on the Ethernet.

Setting the Connection Speed

In order to set the line speed to 115200 bits per second follow the procedure below.

  1. Set the baud rate when you connect the serial line on the target system:

    $ rsh target pppd /dev/tty01 115200

  2. Select Start | Settings | Control Panel.

  3. Click the Modems icon.

  4. Set the Maximum Speed to 115200.

  5. Confirm your selections, closing each dialog box by clicking the OK or Close button.

  6. Select Start|Programs|Administrative Tools (Common)|Remote Access Admin.

  7. Select Server | Stop Remote Access Service....

  8. Select Server | Start Remote Access Service....

  9. Boot the rebuilt ChorusOS system image on the target. It should be immediately visible on the network at the new speed.