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IPNetRouter Troubleshooting Tips

General Information

Understanding the IPNetRouter User Interface

Identifying Problems and Getting Help

Using PPP with IPNetRouter

Cable Modem and Single Ethernet

Using Two Ethernets on NuBus Macs

MacOS 8.5 Compatibility

General Information

Note: For the latest IPNetRouter troubleshooting and compatibility information use your Internet browser to view the IPNetRouter troubleshooting URL:


You may need to restart once after trying to start the Monitor or Router to give Open Transport a chance to build your Link Stack with the supplied STREAMS module included.

Do not change the settings in your TCP/IP control panel while IPNetRouter is running. Quit IPNetRouter first, make the necessary changes in the TCP/IP control panel, and then re-launch IPNetRouter.

You need to uncheck "Load only when needed" in the TCP/IP Control Panel so TCP/IP will remain loaded at all times. Set the User Mode to advanced (under the Edit menu) and click on the Options button to access this setting.

To avoid possible conflicts, configure IPNetRouter before running other TCP/IP software on your gateway machine. This means you'll need to download and print out the instructions so you don't need to have your web browser running while you try to configure IPNetRouter.

Understanding the IPNetRouter User Interface

IPNetRouter is mostly a utility for sending commands to the IP Module in Open Transport.

You specify the parameters of the command in the Configure Interface box, and then send the command by pressing the Add or Remove button. The Interfaces table shows the actual IP interfaces the IP module knows about. When you click on a line in the table, it copies the current information from that line to the Configure Interface box below to save you the trouble of retyping it, thus making it easier to modify an existing interface.

It is the parameters in the Configure Interface box that control what happens, not what line of the table is selected. The IP module identifies which interface you are trying to modify by the interface name field in the Configure Interface box.

If you try to send commands that don't make any sense, the IP Module will not accept them and no changes will appear in the Interfaces table.

There is help available for each window by clicking on the question mark symbol in the lower left corner.

Identifying Problems and Getting Help

TCP/IP networking has many components which can be intimidating when something doesn't work and you want to know what's wrong. The key to troubleshooting network problems is to recognize the sequence of components and look at each one individually to see what isn't working.

You can use the tools in IPNetMonitor to verify whether each leg of your network is functioning correctly. From the gateway machine, you should be able to ping hosts on both your LAN, and the public Internet. From a client machine, you should be able to ping the gateway, and hosts on the public Internet. You can use the Monitor tool in IPNetMonitor to see your ping datagrams leaving one machine and arriving at another. Red bars indicate transmit data while green bars show receive. On the gateway, you can see data being received on one interface (green) and being forwarded out another (red). [IPNetMonitor is distributed as 21-day trialware. Version 2.0 and earlier is included free with your IPNetRouter registration. IPNetMonitor sends 52 byte pings.]

Check that you have specified the correct Name Servers on each machine and that you can ping to them. If your ISP didn't give you any Name Server addresses (becuase they want you to use DHCP), you can use IPNetMonitor to find your default Name Server. Once your gateway is connected, launch IPNetMonitor and press Cmd-L to open the NS Lookup window. Then press Cmd-T to begin a ping test to your default Name Server (used by the NS Lookup window). The IP address of your default Name Server will appear at the top of the Ping window.

IPNetRouter (IPNR) is mostly a utility for sending commands to the IP module in Open Transport. When you save an IPNR configuration, IPNR writes a plain text file that lists the commands needed to restore this configuration. Each line generally corresponds to a row in the Interfaces, Routes, Port Mapping, or Filter windows.

Here's an example of an IPNR configuration file:

#forwardingAutomatic +interface\ \lo0\\\ +interface\Ethernet\mace0\\\ +interface\PPP\IPCP0\\\masquerading\ +route\Direct\\ +route\Direct\\ +route\Default-Gateway\\ #end

Notice you don't need to copy down the window contents or send a screen snapshot to describe your configuration, select File->Save to create a configuration file, and then drag-and-drop your configuration file into your email editor. If you are still having trouble and would like me to help, please include your IPNR configuration as above and the output of the IPNR Log Window. This will allow me to see your entire IPNetRouter setup.

For me to find "a problem", I need to know specifically what didn't work. The IPNR configuration file showing the commands to be executed along with the IPNR Log Window output that shows the result of each command usually provides the information I need.

If a saved IPNR configuration isn't working, try recreating your desired configuration (per the instructions on our web site) and Saving it only after you have tested to see that it works. Saving a configuration that doesn't work will only perpetuate the problem.

If you have questions about configuring other software such as Windows-95, Windows-NT, or TIMBUKTU, check the IPNetRouter FAQ and then try posting your question to our NetTalk mailing list. Other users are likely to have experience with the same issues. TCP/IP networking is too vast a subject for one person to know everything.

You can edit IPNetRouter saved configuration files using any text editor such as SimpleText. BBEdit Lite is particularly convenient because it allows you to edit a file without changing its file type and creator (so it remains an IPNetRouter document). If your editor does change the file type and creator, you can drop the resulting file on the IPNetRouter application to invoke it explicitly and then do a Save As to store this configuration as an IPNetRouter document.

Using PPP with IPNetRouter

You must not have PPP selected as the "Active" interface in the TCP/IP Control Panel.

If IPNetRouter is interrupted during a PPP connection attempt, IPNetRouter may be unable to restore the currently selected configuration in the TCP/IP control panel. In this case, you may need to manually select the desired configuration in the TCP/IP control panel to restore normal operation.

Configuring TCP/IP to use PPP

In the TCP/IP Control Panel, select "Configurations" under the File menu. You must have at least two configurations:

  1. A PPP configuration named "IPNetRouter". This configuration must not be active, but you still need to have it so OT/PPP can find its configuration in the TCP/IP Preferences File. This configuration must be set to allow PPP to connect automatically when launching TCP/IP applications (otherwise the PPP configurator will fail to build a PPP link stack). Notice in Mac OS 8.5 the "PPP" control panel has been renamed "Remote Access."
  2. An Ethernet (or MacIP) configuration with some other name (not "IPNetRouter"). This configuration should be made Active.

In both configurations above, you must unselect "Load only when needed" in the TCP/IP Control Panel. You want TCP/IP to remain loaded at all times.

Cable Modem and Single Ethernet

When using a "Single Ethernet" configuration, your LAN is directly attached to the cable modem network through your hub. It is possible someone else on the cable modem network will try to use the same IP addresses suggested in the getting started example on our web site. If this happens, you could see the following message:

Another device on your TCP/IP internet, which has the physical address 00 10 XX XX XX XX, is currently using the same IP address (dd.dd.dd.dd). Your TCP/IP network interface has shut down.

Notice the IP address reported (dd.dd.dd.dd) may be the address specified in your TCP/IP control panel even though it is the LAN IP address ( that is in conflict. The warning dialog doesn't realize your machine can have more than one IP address.

To work around this problem, you need to choose a different sequence of IP addresses for your LAN. If your LAN is currently using, for example, you could change the 3rd octet to create a different set of addresses:,

Alternatively, you can change to a Dual Ethernet configuration to isolate your LAN from the cable modem network. This makes your private IP addresses truly private (no one else will see them).

Using Two Ethernets on NuBus Macs

If you have a NuBus Ethernet card in addition to "Ethernet built-in", you should use the TCP/IP control panel to configure Ethernet built-in, and IPNetRouter to configure any NuBus cards. If you try to use the TCP/IP control panel to select your NuBus Card, multihoming won't work due to a limitation of the Ethernet driver on these machines.

If your machine doesn't have built-in Ethernet, put the cable modem Ethernet interface in the lower NuBus slot.

MacOS 8.5 Compatibility

MacOS 8.5 introduces Open Transport 2.0 with a number of changes. The main changes are:

  1. OT/PPP is replaced with Remote Access (the full ARA 3.0 client that supports AppleTalk over PPP and ARAP).
  2. A new much faster Ethernet driver for Ethernet built-in.
  3. Improved Finder copy code.
  4. Various bug fixes and additions for developers.

How does this affect IPNetRouter?

  • Previous versions of IPNetRouter may not complete PPP connections successfully with Remote Access. You should download IPNetRouter 1.3 or later to work around this problem.
  • Some 3rd party Ethernet drivers are not compatible with Mac OS 8.5. The Farallon driver for the PN593-C/PN893 (Etherwave/EtherMac) will fail under System 8.5 due to a problem with Apple's ENet driver. The solution is to remove the Apple Enet extension.

Copyright 1998 by Sustainable Softworks.

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