Okay, I have a Macintosh LC running MacOS 7.5.5, and MacTCP and MacPPP properly installed. I have a linux machine nearby connected to my home ntwork wirelessly, and to the mac via an RS-232 -> USB cable and a custom cable I made to do the DB-9 -> mini-DIN 8 conversion. Note that said cable does not have any flow control lines connected, just TX/RX (hence why in the configs I have no flow control set).
MacTCP is properly configured (I think), and in MacPPP I have static IP's set in the IPCP settings. The local address is 192.168.1.248 and the remote address is 192.168.1.249. I also have 192.168.1.1 (the router on my home network) set in MacTCP as a DNS server.
I can connect to the outside world just fine (using DNS to resolve names) using NCSA telnet, so the link is working to some extent.
The problem is that I am unable to use Fetch. Fetch is trying to use the PORT command to open a connection to the .248 address (which if I understand correctly, is where the Mac is on its own "local network"), not the .249 one (which if I understand correctly, is where it actually is on my home network). Yes, checking with ping, the Mac is connecting to my home network at the .249 address, not the .248 one.
I actually DID HAVE THIS WORKING, so I know it should work, but I've changed something in either MacTCP or MacPPP (or maybe both) and now it's broken.
Pictures of the configs for MacTCP and MacPPP are in the attached zip file, along with the script the linux machine uses to start pppd.
I think that's everything, but if I forgot something let me know.