problem with dropbear, pty??, and busybox

[Matt Johnston]

On Thu, Jun 21, 2007 at 09:41:07PM +0200, Hans-Jürgen Koch wrote:
> I'm trying to use dropbear-0.49 on an ARM board (PXA270) running 
> Linux 2.6.21.5.
> I'm using busybox-1.6.0 (don't know if that's related).
> 
> The dropbear daemon starts without complaining. If I try to login with ssh
> from an other computer, authentication (password) works, but then dropbear 
> hangs and spits out this error:
> 
> failed to open any /dev/pty?? devices
> no pty was allocated, couldn't execute
> 
> It's true, I don't have any /dev/pty devices. I used
> 
> ./configure --disable-syslog --disable-openpty --disable-utmp --disable-utmpx
> to avoid them.

You need some sort of PTY support to run any sort of
virtual terminal (ie, a normal SSH login). I have got no
idea what sort of Linux distro you're using, but often
they'll take care of it for you.

You will have to create the appropriate PTY devices in /dev
for it to work. If you make sure /dev/ptmx and /dev/tty
devices exist (use mknod or the makedev script that come
with your distro (or buildroot??)) and then mount devpts at
/dev/pts, you should be able to use normal openpty()
support. You'll want to get rid of the --disable-openpty
configure argument.

Alternatively you can manually create 
 /dev/[pt]ty[pqrstuwxyzPQRST][0123456789abcdef]
nodes as appropriate and keep the --disable-openpty
configure argument. That will try opening each of
those devices sequentially until one succeeds.

Cheers,
Matt