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

jcassara

Member
Faced with the dilemma of how to get files between my little Powerbook Duo 280 and Intel iMac and, better yet, getting her on the Internet, I took to the grand oracle Google for enlightenment. What I found were solutions requiring hardware and software I didn't have access to. My only tools: a KeySpan USB to Serial adaptor, serial cable, and telecom software on both ends.

That would be fine for the short term, and sending files to and fro via Zmodem sure brought back memories. But I wanted something a little more elegant. OS X doesn't support AppleShare over AppleTalk on LocalTalk, so that was out. And what was I to do about internet access?

Then it hit me -- I have a UNIX based machine sitting in front of me. One that surely has a PPP daemon. I could configure my iMac as modem-less dial-up ISP, and then use FreePPP/OtTCP on the Powerbook to access the 'net. Furthermore, OS X's FTP server would serve as a much nicer file transfer scenario than ZTerm.

So, in a nutshell, I:

1. Mated the Powerbook and iMac using the KeySpan adaptor and serial cable.

2. Used ZTerm (iMac) and Microsoft Works Communications (Powerbook) to transfer over FreePPP and iCab. (Had this Powerbook not had OS 8 which includes a TCP/IP stack, I would have used MacTCP.)

3. Configured TCP/IP with an IP address local to my network (in this case, 192.168.1.245). Used OpenDNS IP addresses for the DNS.

4. Configured FreePPP to use the Serial/Printer port, in lieu of the Powerbook's modem. Left the phone number field empty. Set the baudrate to max (230400).

5. Run the following with root privileges on the iMac:

sysctl -w net.inet.ip.forwarding=1

(tell the Kernel we want to forward IP packets)

pppd 230400 tty.KeySerial1 local persist passive maxfail 0 proxyarp 192.168.1.102:192.168.1.245

(activate the PPP daemon at 230400, using the KeySpan's #1 serial port, don't use modem control lines, persistent connection, don't dump out if the peer isn't there, ditto, add to ARP table so other networked machines can see it, Ip address of the iMac:Ip address of the Powerbook)

6. Pressed "connect" on FreePPP.

Would you believe it worked right out of the box?

I am now cruising the internet, telnetting, FTPing, and other wonderful things on the Powerbook Duo 280, courtesy my own private non-dial-up dial-up ISP. The best part: no docks or additional cables to buy. Sure, it's not as fast as ethernet. But that's an opportunity cost I'm willing to pay for close to zero financial investment. And it's a "universal" solution, in that I can get any platform that supports PPP and TCP/IP online this way. Anyone care to surf the web using Lynx on my Amiga 1000?

Cheers! ;D

 
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jcassara

Member
Hold on a second, fellas! I don't think this should have been moved to the Powerbooks forum. Did you read it? This solution works with any old world Mac that has a serial port. The only thing Powerbookie about it is my personal experience. I'd hope this solution would be available to all users of 68k Macs!

 

aftermac

Well-known member
Pretty slick!

Correct me if I'm wrong, but if you don't specify the IP addresses at the end of the pppd command wouldn't you, in theory, be able to use phonenet connectors and use this technique with multiple vintage macs simultaneously?

If I understand this correctly "192.168.1.102:192.168.1.245" statement limits you to a 1:1 relationship. However, if this is not specified the iMac (in this case) should obtain the address that you manually entered into the peer (Duo).

It's a theory anyway... I could be wrong, but it wouldn't hurt to try.

 

MacMan

Well-known member
This looks like a bit of a breakthrough. I'll have a play with this at some point and see whether I can get my Mac Plus connected through my G4. It would be great to have a non-ethernet solution for hooking 68K Macs up to my internet connection.

 

LCGuy

LC Doctor/Hot Rodder
Very cool!!!!! Why did i nor anyone else ever think of that? :embarassed: That is awesome!

 

jcassara

Member
Correct me if I'm wrong, but if you don't specify the IP addresses at the end of the pppd command wouldn't you, in theory, be able to use phonenet connectors and use this technique with multiple vintage macs simultaneously?
I'm not familiar with how Phonenet works, so I don't know. My gut says it wouldn't work because we'd need mutple PPP daemons running, and only one daemon can run on a given serial port at any time -- where the real "1 to 1" relationship begins. But, hey, I almost wrote off my project thinking Apple had crippled pppd in OS X. Nothing ventured, nothing gained! If you try it, do let us know!

 

JWG Design

Active member
Congrats on getting the Duo on the net. That is a rather clever solution.

Perhaps it isn't as fast as ethernet, but it could still be quite fast.

Back when I first got DSL (and before hardware routers were affordable), I ran IPNetRouter on my Quadra 840av to share the DSL between several Macs and a PC. Most of the computers were on ethernet, but my Powerbook Duo 280c was on LocalTalk. The Quadra must have been able to pump up the serial port speed past what was normal for the Duo, because the Duo could download files via FTP at around 80KB/sec. That is equal to 640kbps, which is much faster than the typical 130kbps it should have been getting, and pretty close to the 768kbps DSL I had.

For comparison, the Centris 650 Macs that I had in my computer lab in college would get between 80-100KB/sec download rates over ethernet. Any way you look at it, it will be leaps and bounds better than dial-up.

I am not sure what your USB-to-Serial adapter is capable of, but the one I have here at work handles rates up to 230kbps.

From the way I understand it, you are using direct serial communication between the Powerbook and iMac. That is where the 1-to-1 ratio lies. If it was doing LocalTalk (MacIP for TCP/IP networking), then you could have approx. 250 computers daisychained to your iMac. AFAIK, serial communications are limited to 2 devices though.

 

aftermac

Well-known member
Yeah, you guys are probably right... It was a thought anyway.

By the way, which serial adapter are you using? The twin adapter? PDA adapter? I'm not sure if it would make a difference or not (other than the cables you would need). I have the PDA serial adapter. I'll have to give this a try when I get a few mins.

 

jcassara

Member
I am not sure what your USB-to-Serial adapter is capable of, but the one I have here at work handles rates up to 230kbps.
According to the manual, the data rate on the USA-28x maxes out at 1Mbit/s. FreePPP's modems configuration panel tops the data rate at 230kbps (which is interesting, as Low End Mac's entry for the Duo claims the limit is 56kbps).

My next goal is to get the Duo into the wireless age with a pair of RS-422 to Bluetooth transceivers. (At $199/unit, maybe not soon...) ;D

 

Bunsen

Admin-Witchfinder-General
If and when the pre-crash threads are recovered, there's a great thread there about potential wireless solutions for Duos.

 

benjgvps

Well-known member
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Would this work for connecting to a pc with a serial connector? How would I go about networking for just file sharing and possibly internet sharing from windoze? Any body know of a canadian website to get the cable? sorry to bombard you guys with questions.

 

Moof

New member
I've been trying a similar thing with my PowerBook 2300c Duo with Mac OS 7.6.1. I've got it hooked up to my MacBook Pro 17" with a Keyspan USA-28 serial adaptor. FreePPP says 'Establishing Conncetion' and eventually says 'Link Dead'. Any ideas on this one?

I was wondering - what are your FreePPP settings? Modem? Speed? Flow Control? What did you do for a Connection Script?

Thanks!

 

JWG Design

Active member
I've only done a direct serial connection with a terminal program like Z-Term or the Communications mode of ClarisWorks. In that situation, you'd need to select Null Modem Cable from the list of modems.

If you are using PPP, then you would also have to select Null Modem Cable. The "server" computer would have to have some software running to accept the connection and assign the client an IP address. I'm not sure how that would be done.

 

Forrest

Well-known member
If you have a DuoDock for your 2300c, just connect your Duo to your cable/DSL modem and use iCab to browse the web.

 

Moof

New member
I was referring to the first post made here since this fellow managed to his working with the same equipment as me. ZTerm and ClarisWorks Communication works but is very very slow so using FreePPP would allow me to use FTP as I can setup an FTP server on OS X and access it using Fetch on the Duo. I followed his instructions but it doesn't actually connect :( pppd on OS X is supposed to provide the IP address and such if it connects.

 

benjgvps

Well-known member
Sorry to revive a dead post here, but would this be possible to do over two modems connected together?

 

porter

Well-known member
Sorry to revive a dead post here, but would this be possible to do over two modems connected together?
Via the PSTN yes. One is the server and waits for connections, the other is the client who dials and connects.

I would doubt you can just wire two modems back to back and expect them to work, they normally expect ring tone before dialling out.

Correct me if I'm wrong, but if you don't specify the IP addresses at the end of the pppd command wouldn't you, in theory, be able to use phonenet connectors and use this technique with multiple vintage macs simultaneously?
No, the clue is in the name, PPP stands for Point to Point Protocol.

 
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