🚀 go-pugleaf

edhall@rand.org (Ed Hall) writes:
>don't expect [KA9Q NOS] to interface with other network software.  To
>do that, you need to either put PPP in the kernel, or use a "tunnel
>driver" like MorningStar does with their PPP (a pseudo-device driver
>which allows a user process to pump IP packets into and out of the
>kernel).

If your computer already supports SLIP, you can do this with a PTY. I
wrote a small user-level program that just tunnels bytes between a PTY
and a TTY. Running SLIP through this "bridge" adds a few copy
operations between kernel and user memory. This gave me no measurable
decrease in throughput (using ftp), and only little longer response
times (using ping). My TTY line does 9600 bit/s TTY line. The slow TTY
line is the real bottleneck here, so you could probably do this on
much slower computers than my HP 9000/400 running HP-UX 8.0 and
IBM-compatible 486 PC running SCO UNIX.

I did this only for some experiments, and as an exercise, and didn't
use it later. The problem I never solved was opening a PTY with a
well-known name. The SLIP implementation used (HP-UX PPL) wants the
name of the underlaying SLIP device to be written in a file, and I
don't know the name of the PTY until I have successfully opened it. If
a window system grabbed my favorite PTY, I would have to use another.

I never tried to translate between SLIP on the PTY and PPP on the TTY,
so I cannot know how much overhead that would have caused.

Is anybody from Hewlett Packard out there? How long do we have to wait
for HP's PPL product to implement the PPP protocol? It has been a
promise for a long time now.
-- 
Lars Aronsson, SECTRA AB, Teknikringen 2, 583 30 Linkoping, Sweden