serial consoles

Matthew Luckie mjl at
Sat Dec 24 10:02:39 UTC 2011


I'd like to be able to login using a null modem cable to a freebsd 
server, from a freebsd laptop.  It doesn't need to display boot 
messages, just allow me to login after the system has booted.

I've got a null modem cable connected to my freebsd server, and on the 
other end is a USB serial port on my laptop.  On the server I've got:

uart0: <16550 or compatible> port 0x3f8-0x3ff irq 4 flags 0x10 on acpi0
uart0: [FILTER]

in /etc/ttys on the server:

ttyu0   "/usr/libexec/getty std.9600"   vt100   on  secure

and there is a getty running on that:

$ ps xa| grep getty
  1825  ??  I      0:00.00 /usr/libexec/getty std.9600 ttyu0

On the laptop, I have:
ugen1.2: <FTDI> at usbus1
uftdi0: <USB to Serial Cable> on usbus1

as well as cuaU0 and ttyU0 entries in /dev.

However, when I use cu on the laptop:

sudo cu -l /dev/cuaU0 -s 9600

I never get a login prompt.  If I press enter, the cursor scrolls down. 
  Likewise other characters echo back.  I'm reasonably sure that I'm 
connected to the appropriate com port on the server because if I plug it 
into the other com port and press enter, nothing happens.

It feels to me that I'm missing something basic.  Can someone provide me 
with some clue?

Note: I'm reasonably sure the null modem cable and USB device are fine, 
I've used them recently on an arm board (gateworks) running freebsd and 
it worked fine then.


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