The Interfaces window allows you to configure and bring up additional IP interfaces (multihoming) under Macintosh Open Transport.
The table starting at the top of the window shows the IP interfaces that are currently defined. The Configure Interface box immediately below the table allows you to specify an IP interface so you can "Add" or "Remove" it to modify the current configuration.
Each interface can be either Up or Down as indicated by the corresponding green or red arrow. The "Port Name" identifies the physical port (such as "Ethernet", "PPP", or "AppleTalk (MacIP)"). The built-in Ethernet port is normally identified as "Ethernet". Additional ethernet cards might have different names. A popup menu below the "Port Name" column allows you to select from the physical ports available to Open Transport. Selecting a port will automatically fill in the corresponding module name used to identify the interface (see below).
The "Interface Name" specifies the device driver module and a unique interface number. The Ethernet driver module on PCI Macintoshes for example is "mace". The first interface on the built-in ethernet port would be identified as "mace0" (which is an abbreviation for "mace0:0"). Additional interfaces on the same port are distinguished by appending a ":" and another digit. Thus the second interface on this port would be called "mace0:1". Notice that by creating more than one logical interface on the same physical port, you can have a single physical port respond to more than one IP address (useful for virtual hosting). Use the up and down arrow buttons to the right of the Interface Name to specify a unique interface number for the selected port as needed.
To configure an IP interface, you need to specify the "Port Name", "Interface Name", "IP Address", network or subnet "Mask" and select whether to "Bring Up" or disable that interface in the corresponding edit fields below the IP interface table. After entering the appropriate information, click on the "Add" button. The interface table will automatically be refreshed to show any changes or new interfaces that have become available. If there is a problem configuring the interface, the "Status:" field and Log Window will try to report what happened.
To bring up a PPP (point-to-point) interface, you must leave the IP Address field empty if you want to use an address dynamically assigned by your ISP.
Use the "IP Masquerading" check box to enable Network Address Translation on this interface.
The "Unnumbered" check box may be used for point-to-point interfaces for which no unique local address is provided. If you have been assigned a block of IP addresses by your ISP for example, you would select "Unnumbered" to give your PPP interface an IP address from the same range assigned to your LAN (an "unnumbered" interface).
Use the "DHCP" check box to indicate that this interface will be configured by DHCP (specified in the TCP/IP Control Panel). This prevents the current IP address from overriding an address assigned by DHCP when this IPNetRouter configuration is restored.
Clicking on a row in the interface table will automatically transfer the corresponding information to the data entry fields below the table. To remove an interface from the table, select the interface and press the "Remove" button. Notice interfaces may not disappear from the table until there are no more active interfaces on that same port. This is because IPNetRouter is displaying the actual interfaces the IP module knows about and there is no direct way to delete the data structure for a single interface on a port that is still active.
If the TCP/IP stack is unloaded while you have additional interfaces defined, IPNetRouter will automatically try to remove them. You should insure the TCP/IP stack does not unload by unchecking "Load only when needed" in the TCP/IP control panel. IPNetRouter remembers any Link Stacks you have created and will automatically remove them when you quit the program.
You can save an IP configuration (interfaces and routes) to a settings document and then restore this configuration later by opening the corresponding document. Since the "Interfaces" and "Routes" window show the actual interfaces and routes the IP module knows about, you can only open one document at a time to restore a previous configuration (since there is only one IP module). Use the "Upon Open" popup menu in the Gateway window to control what happens when a configuration document is opened (configure only, configure and display). This is especially useful for placing a settings document in your Startup Items folder to configure multiple IP interfaces each time your Macintosh starts up.
The "Connect"/"Disconnect" button is used to control a dial-up interface that does not remain permanently connected to a remote network. Press Cmd-Period to reset the state of the "Connect"/"Disconnect" button if necessary.
Detailed instructions for using IPNetRouter are available from the Sustainable Softworks web site at <http://www.sustworks.com>.
