modem / pon / serial problems
Hi,
My motherboard has no ISA slots, but my (hardware) modem is an ISA
device. So, to make it usable, I have a second machine which does have
ISA slots. This is connected to the main machine by a 3-wire crossover
serial cable, and runs a DOS program to copy the external serial port
to the modem's serial port, and vice versa.
With this arrangement, pppconfig can't autodetect the modem, but if I
enter the serial port by hand and add "nocrtscts" to
/etc/ppp/peers/provider, the dialup works.
The modem box is a 600MHz Celeron, and I think it could be better used
than simply running a tiny little DOS program. So I networked it to
the main box and installed woody on it. That worked fine; I can ssh
into it and muck about, mount NFS exports from the main box, etc.
Ultimately it's gonna be a print server and a firewall for the main
box, and will talk to the modem itself. But it'll take me a while to
get this working, and in the meantime I still want it to copy data
from one serial port to the other so I can continue to dial out as
normal from the main box.
Of course, Linux can't run my DOS program. But there's a package
called snooper which seems to do the same thing. So I installed it on
the modem box and set it up to connect the external and modem serial
ports. Try pon from the main box - nothing. 0 characters sent or
received.
I replaced the 3-wire serial cable with a "proper null modem", RX/TX
crossed, RTS/CTS crossed, DTR/DSR crossed, CD and GND straight
through. Now pppconfig autodetects the modem OK. snooper shows "AT"
being sent and echoed, "OK" being returned, then loads of garbage
ending with "Loopback detected", and pppconfig correctly selects the
serial port. And of course I don't need "nocrtscts" in
/etc/ppp/peers/provider. But I still can't dial out. I try pon and I
still get 0 characters sent or received.
I tried it without snooper:
cat /dev/ttyS1 | tee /dev/ttyS2 &; cat /dev/ttyS2 | tee /dev/ttyS1 &
Same result. pppconfig sends "AT", receives "OK", sends loads of
garbage ending with "Loopback detected", and selects the correct port.
pon, however, sends nothing at all.
To recap:
Main box connected by serial cable to modem box. Main box trying to
run pon (and pppconfig); modem box runs prog to copy one serial port
to the other.
With 3-wire serial cable/"nocrtscts" and DOS prog: pppconfig doesn't
work, pon does.
With 3-wire serial cable and Linux progs (snooper or cat): nothing
works.
With 8-wire serial cable and DOS prog: irrelevant, DOS prog doesn't
handle hardware flow control.
With 8-wire serial cable and Linux progs: pppconfig works, pon doesn't.
Any ideas why pon refuses to send anything, and how to kick its arse?
Pigeon
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