Turning Your Mac Into a Serial Console Server

chrisbw writes "Want to put that old VT100 terminal to use? Mac OS X Hits has a story on how to make a couple simple changes in OS X to enable login on a serial terminal (even over a USB serial adapter if you're on a newer mac). Cool trick for adding a text-based web surfing or email terminal in another room, or remote iTunes control!"

Comments

Re:USB

[chrisbw]

Well, my point was that if you're on a newer Mac that doesn't have a serial port, that you can use a USB serial adapter and OS X will happily use it as a regular tty.

Re:Not much point

[DavidS]

I think you've missed the point entirely.
This also goes in with the story being mis-named. One of the nicer things about having serial console access to your machine is you have the ability to do things like if you were directly at the console... I don't think you're going to drop your system to single user mode while using the network. Or, if you're configureing something, and you accidentally mess up network connectivity, its a very nice backup. Also, on real hardware like suns, you can send serial breaks over the line, get into firmware, and do what is necessary, whether it be synching the machine due to crash, or whatever.

This story is also missnamed.. a serial console server is a server with a lot of serial ports on it :) (used to connect all your serial console machines togother)

Now, I'm not entirely sure what the use of a serial console is under osx, but the impression I'm getting is that its getting a bit more useful each revision of that OS. But under any other unix, not having a serial console in a production enviroment is just asking for trouble.

David

Re:Not much point

[rohanl]

There are problems using PCs as dumb terminals. I remember a while ago at work we had a couple of Windows PCs hooked up to some Sun boxes, as dumb terminals. Of course the Windows PCs needed rebooting every now and then. Each time we rebooted them the Suns stopped.

We discovered that the PCs were sending a BREAK on the serial port, when they got rebooted. Once the came back up again, we'd find the Sun box sitting at the open firmware prompt:

ok>

Once we knew the problem, we could just unplug the PC before rebooting, but there were still lots of times someone forgot to do that.

It was VERY annoying

real serial console?

[GrumpyOldMan]

OK, so the article tells us how to enable logins from a serial port. That's great, but that's really only 1/2 the battle.

For various reasons (mainly driver development in a cramped office), I like to run serial CONSOLES. This means I want to see the kernel messages on the serial port, not on a VGA monitor. This allows me to log all kernel messages, even messages from a machine which crashed (hence syslog is not running). Otherwise, its easy for important messages to scroll off screen and be lost when the system crashes.

When running linux, getting a serial console is as simple as passing some parameters to the kernel (console=ttyS0). Similar options exist for FreeBSD, Tru64, Solaris, etc. All of them will use a serial port for a console.

With OS-X, I've been able to enable some extra verbosity on the serial port, and I'm able to get
an openfirmware prompt on the serial port, but I can't figure out how to make the serial port the actual system console. I know it must be possible, because the X serves are supposed to be able to do it.

Does anybody know how to do this on a "normal" g4 with a serial port (g4port)??

Open Firmware boot to serial input

[Anonymous Coward]

Yes.

This might answer your questions (look at section 6):

http://www.netbsd.org/

Short answer:

setenv input-device ttya
setenv output-device ttya