Sharing COM ports to Windows hosts

Polytropon freebsd at
Mon Sep 3 10:04:02 UTC 2012

On Mon, 3 Sep 2012 10:02:17 +0700, Victor Sudakov wrote:
> Colleagues,
> There is a FreeBSD box with several RS232 ports. Can those ports be
> accessed by Windows hosts over the network? Actually, does anyone
> have a success story for such a scenario?
> There is some software like comms/serialoverip, comms/tits etc but are
> there any (freeware) Windows virtual COM port drivers compatible
> therewith?
> Maybe some Windows drivers for hardware console servers (like Moxa)
> would work with tits etc?

It is _easily_ possible, even though my own experiences do
not include doing this with "Windows", but with other BSD
boxes and even DOS.

First you have to enable a serial terminal connection just
the same way you handle the virtual terminals in text mode:
Edit /etc/ttys and enable the line

	ttyu0  "/usr/libexec/getty std.19200" dialup  on  secure

Now you can connect to that port via a serial cable, using
a terminal emulator (for example Kermit). Make sure you have
set the proper speed, 19k2 in this example (faster than the
default 9k6). See "man 5 ttys" for examples.

If you use a UNIX or Linux client, you can use the "cu" program.
See "man cu" for details.

However, what you need on "Windows" side is a program that can
communicate via serial port. I don't know if such a program is
still included in today's "modern" versions of "Windows", but
I seem to remember that the 3.11 and 95 versions came with such
a program. In worst case, maybe you can use a DOS program like
Kermit under "Windows"? I'm sure the compatibility is restricted,
but maybe you can give it a try.

Note that I haven't tried this with any recent FreeBSD system.
But it _was_ possible with FreeBSD 4 and 5.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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