The Gateway Window allows you to configure the operation of the IPNetRouter
gateway.
IP Forwarding: It is possible to receive datagrams on an IP interface whose IP address is not an address for this computer. In this case, you can decide whether to discard such datagrams (normal behavior), or try to forward them on to their destination. Select "IP Forwarding: Never" to discard datagrams that are not addressed to this machine (RFC 1122 compliant). Use "IP Forwarding: Always" to always forward datagrams. Use "IP Forwarding: Automatic" to only forward datagrams when more than one IP interface is active (SunOS compatible).
In general, only designated routers should forward datagrams, but there are situations where you might want one machine to forward datagrams to another that would not otherwise have access to that network.
Dial On Demand: When selected, IPNetRouter will request PPP to connect when it detects IP traffic sent to a PPP interface that is not connected. The Log Window shows the source IP address of the datagram that triggered the dial request. When unselected, IPNetRouter will open PPP before requesting a connection so PPP can decide when to dial for the first time. Press and hold the Option key while adding a PPP interface to temporarily override this behavior.
Show PPP Dialogs: Enables the PPP modal dialogs to appear when connecting or disconnecting using OT/PPP.
Remain Connected: Causes IPNetRouter to ping a PPP interface every three minutes and try to reconnect immediately if the PPP connection is lost for any reason.
Disconnect PPP At Quit: IPNetRouter will request PPP to disconnect when the application quits.
Enable Local NAT: Allow Network Address Translation on datagrams received from other interfaces. This setting allows data from the LAN addressed to the public IP address of the gateway to be port mapped to machines behind the gateway.
TR Cable Modem: For Telco Return style cable modems that use an Ethernet downlink and PPP uplink over a telelphone line. Selecting this feature tells the NAT module to unmasquerade packets received on the first Ethernet interface that were masqueraded by the PPP interface.
Use Network Setup: For Mac OS 8.5 and later, IPNetRouter tries to use Network Setup if available instead of modifying the TCP/IP Preferences File directly to insert its Proxy module. This has the advantage of rebuilding the TCP/IP link stack immediately if needed. If IP masquerading isn't working, you can press Option during application launch to force the link stack to rebuild. Unselecting this item (pre 8.5 behavior) may allow IPNetRouter to launch more quickly or avoid compatibility issues with Network Setup.
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.
Detailed instructions for using IPNetRouter are available from the Sustainable Softworks web site at <http://www.sustworks.com>.
