serial consoles

Da Rock freebsd-questions at
Sat Dec 24 11:04:51 UTC 2011

On 12/24/11 19:34, Matthew Luckie wrote:
> Hi
> 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.
You sure its not easier to run a crossover UTP cable to the server? Then 
you can just ssh or similar to login to the server. From my 
understanding the null modem cable is used primarily for accessing the 
boot console - no login.

Failing that, you'd probably need a RAS setup; probably mpd, but you may 
get away with the base pppd. Network is probably you're quickest and 
easiest bet.


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