Remote modem via serial port proxy.

Mike A. Harris (mharris@ican.net)
Fri, 21 May 1999 07:35:17 -0400 (EDT)

I would like to do use a modem in a remote computer locally in
another computer as if it were in the local machine. Here is the
scenario:

I have 1 modem, and for internet related purposes, IP
masquerading, works great. My Linux box has the modem in it, and
I want to move the modem into another dedicated linux box so that
my machine doesn't have to be in Linux for other machines on the
network to access the net.

This poses a problem though. If I put the modem in the other
box, it doesn't effect internet usage, however it does affect
DIRECT MODEM usage, such as for direct modem multiplayer games.

I came up with an idea that if I connected my spare serial port
on my one machine - via null modem - to the spare serial port on
the other machine (the one with the modem), that the modem could
be directly accessed (as long as not in use) by the remote
computer - IF - the machine with the modem had a special driver
which would transparently connect COM2 (null modem) to the COM3
(modem) via software.

That way, the remote windows machine, could treat it's COM2
serial port as a real modem. The data leaving the windows
machine goes out over the null cable, enters COM2 on the modem
server machine, the driver sends all incoming data to COM3 which
is the real modem, then sends any data from the modem on COM3
back through COM2 null modem, back to the original computer.

This way, the Windows machine doesn't have to be modified, nor no
special windows software written, yet the modem can be shared.

I think this is a wonderful idea, and I'd like to know if anyone
has developed such a driver allready?

If not, I am wanting to take on the task myself, and I would like
to have some advice on how to proceed, and what unknowns I should
be aware of. I haven't done any low level UART code in quite a
while, but could if I needed to.

Does the kernel serial code, contain enough of an API, that I
could write a simple proxy driver like this without directly
touching the UART's?

Thanks very much in advance.
TTYL

--
Mike A. Harris                   Linux advocate      GNU advocate
Computer Consultant                          Open Source advocate  


Tea, Earl Grey, Hot...




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