problem with dropbear, pty??, and busybox

[Rob Landley]

On Friday 22 June 2007 06:02:24 Hans-Jürgen Koch wrote:
> Am Freitag 22 Juni 2007 08:08 schrieb 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.
>
> It's not a real distro, I compiled a minimal root file system
> using busybox plus the files that come with the scratchbox
> ARM toolchain. I haven't installed udev yet, that's why I
> only have the /dev files I created myself.

mkdir /sys
mount -t sysfs /sys /sys
mdev -s

Note that mdev is a busybox command, and very simple udev replacement.

http://busybox.net/downloads/BusyBox.html#item_mdev

However, for ptys you should probably be using unix 98 pty support, which 
dynamically allocates them:

mkdir /dev/pts
mount -t devpts /dev/pts /dev/pts

Rob
-- 
"One of my most productive days was throwing away 1000 lines of code."
  - Ken Thompson.