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Networking a Powerbook Duo: serial -> OS X/unix -> internet

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This one is old, but i guess it fell through the cracks. 8-o


My question is: when I want to stop the connection and the IP forwarding, I just type:

sysctl -w net.inet.ip.forwarding=0

or is it more complicated than that?


That would just stop IP forwarding. The OSX kernel can either transport packets from one network to another, say, from your 68kmac-OSX-serial-network to your OSX-ISP-network, or not. That is all. The 68kmac-OSX-network still runs, as long as the serial connection is established. Wich means, you can still accesss a FTP server on your OSX machine, but not on the internet. To stop the serial connection, kill the ppp daemon or client.

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Just kind of stumbled on this thread...the modem-to-modem connection is definitely possible. There are two things you need to fix to enable this:


First is line power -- all telephone lines provide a low amperage power to communicate/power phones/etc.


this page describes the "line simulator" that is required to make this work. http://www.jagshouse.com/modem.html


Second part is the modems themselves. There are several lines between a modem and serial line that need to be possibly manipulated. An example I can think of is the following:


I had a laptop with a modem (running linux) that connected to the 56k modem on my dreamcast. There was a web browser disk that would allow you to dial up to a ISP and connect to it, and allow you to browse the web. The first part is the easiest --- the physical part. Hook em up together. Done.


The second part is telling the OS on the "server" side that whenever the modem answers, it needs to provide IP services (PPP). Typically, in windows, this is provided via DUN listening on a serial port.


Now, the last part is the oddest part and the one I dont 100% remember: Ordinarily, modems are connected via telephone switching stations, which take one active call, route it to where it needs to go, prefixing that "connection" with a telephone ring. The idea is to simulate that. You'd dial any number, setup PPP/DUN, and to connect the call, you'd connect the lines together. The modem would detect the carrier and the ringing noise on the line, put the modem off the hook (answering the call) and there ya go. You *may* have to configure the dialing end to "ignore dial tone before dialing" because there wont be a dial tone. But once the modem dials the number, it'll send out carriers and the "server" modem will be listening.

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  • 4 months later...

I have managed to make this technique work in OS X*.


*: But only OS X 10.4 (haven't tested lower). In 10.5, I'm still in the process of working on figuring out how to revise the command so it works correctly. For 10.4 and the LCII with a USB FTDI RS232 adapter, I type:


sudo /usr/sbin/pppd 38400 tty.usbserial-A601FT6I local persist passive maxfail 0 proxyarp


In 10.5, running this command in a separate Terminal window is a good idea:


tail -f /var/log/system.log


During a session of monitoring the output, I get some issues in 10.5 which make it not work. I don't have 10.6 or higher so I can't speak for those.


I use MacPPP 2.0.1 in System 6 and 7.0.1. System 7.0 and 7.1 have a most abhorable bug where the MacPPP INIT can't start because of "insufficient memory". I tried 2.1.1SD (can't find 2.0.1cm4, but probably won't fix it) and 2.2.0a and all had the same exact problem. Basically this is the equivalent of shipping a car to consumers with no windows on it.


The proper command for Linux is also something I'm working on. The only real digest worthwhile is some pages which are over a decade old and pertain to kernel 2.0 and 2.2. :o)

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As I thought about this process, I wondered if there is a way to pipe Lynx output from a host *nix or OS X computer to ZTerm .9 or 1.0b on a old mac over a serial port.


jag does mention it:


If everything goes as planned, you're in. If it doesn't, make some coffee and read a few Dilbert strips. After the obligatory intorduction text appears and stops scrolling, type the word Lynx and hit the enter kley. If your ISP has Lynx on their server, you should automatically go to a web page, more than likely it will be your ISP's home page. You are now on the web with 1 meg of ram!

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This is kinda crazy - I recently dug out and resurrected my old PowerBook 1400, and I'm dying to get it back online. I've gotten there, sorta, by leveraging a serial cable and my handy-dandy Simple WiFi232 modem, which allowed me to access some BBS's using the Communications tool within ClarisWorks, but I'd love to go a big step further and get some real Web access going. This method sounds like just the thing, since I have the serial cable and at least a couple Keyspan Serial-to-USB adapters floating around. Looking forward to trying this soon!

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