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Re: USB "null modem" cables and related Linux driver questions




On 05/31/2018 06:58 PM, David Wright wrote:
On Thu 31 May 2018 at 09:21:27 (-0500), Richard Owlett wrote:
I have two computers with USB ports.
I wish them to communicate as simply as mid-20th-century computers did.
Then we used RS232-C with a null modem &/or  appropriate software
software at both ends.

I remember soldering these cables together. It always seemed crazy to
be paying as much for a cable as a floppy drive.

The underlying problem is that both ends egotistically expect to be
*MASTER*.

The hardware problem is solvable [e.g.
http://www.ftdichip.com/Products/Cables/USBtoUSB.htm].

https://shop.clickandbuild.com/cnb/shop/ftdichip?op=catalogue-products-null&prodCategoryID=354&title=Null+Modem+Cables
(thanks for your link) gives an idea of the price, and in this case I
can see some justification for it because they describe the
electronics hidden inside the plugs (we hope).

But considering that two NICs cost less than that cable, I'd need a
pressing reason to purchase the cable instead.

There is a perceived elegance aspect.
There is also a practical aspect the only known working and conveniently physically accessible ports are USB.


The software is another case :<
The best Linux specific link I've found is dated September 2005
[http://www.linux-usb.org/usbnet/]

I've done DuckDuckGo searches for permutations/combinations of
   usb, "peer to peer", lan, and bridge.
Most is Windows/Mac centric.
There were hints that needed drivers may exist in current Linux core.

Pointers to good references and/or better search terms?

"ppp over usb" gave me http://www.linux-usb.org/usbnet/
which might be what you want. I notice that such a module is
in the production kernels.

I had seen the page. It told me that I was not pursuing an impossibility. I was hoping for a more recent reference than 2005.




Cheers,
David.