Subj : openbsd telnet to serial
To   : bbsing
From : phigan
Date : Tue Dec 02 2025 03:50:03

  Re: openbsd telnet to serial
  By: bbsing to phigan on Sat Nov 29 2025 09:45 pm

 > I don't see any way to tell telnetd to only use the serial port. I think
 > telnetd likes psuedo ttys .

Well no, you'd tell the software using telnetd to use the serial port instead.

 > terminal, or the terminal emulation software, from "half duplex" or "local
 > echo" to "full duplex."

The half/full duplex thing is unrelated. Yes, you can set "half duplex",
meaning the other end won't send stuff back to you so you need your local
terminal to "echo" the characters you type for you. Or "full duplex" where the
stuff you send out gets sent back, so you don't need your terminal to do it.
Most (if not all, now) connections you make will be full duplex, so if you have
your terminal set at "half" (aka "local echo on"), you will see double
characters... the ones echoed locally by your terminal as well as the ones sent
back from the other side. When typing your password, the other side doesn't
send back characters, but you will still see the locally echoed characters if
you are in half duplex.

So, very similar problem with the telnet vs raw connection mismatch, but in
this case you are not setting the duplex with your terminal program. It is
being auto-negotiated (or attempting to be) by 'telnet' on one side or the
other.

If you are connecting to a telnetd, you should use a telnet client. If you are
connecting to getty or something else answering the connection and just passing
it along to 'login' or what-have-you, you should make a raw connection (like
with netcat or a BBSing terminal program).

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