debian/dropbear.README.Debian

Dropbear for Debian
-------------------

This package will attempt to listen on port 22. If the OpenSSH 
package ("ssh") is installed, the file /etc/default/dropbear 
will be set up so that the server does not start by default.

You can run Dropbear concurrently with OpenSSH 'sshd' by 
modifying /etc/default/dropbear so that "NO_START" is set to 
"0" and changing the port number that Dropbear runs on. Follow 
the instructions in the file.

This package suggests you install the "ssh" package. This package 
provides the "ssh" client program, as well as the "/usr/bin/scp" 
binary you will need to be able to retrieve files from a server 
running Dropbear via SCP.

Replacing OpenSSH "sshd" with Dropbear
--------------------------------------

You will still want to have the "ssh" package installed, as it 
provides the "ssh" and "scp" binaries. When you install this 
package, it checks for existing OpenSSH host keys and if found, 
converts them to the Dropbear format.

If this appears to have worked, you should be able to change over 
by following these steps:

1. Stop the OpenSSH server
   % /etc/init.d/ssh stop
2. Prevent the OpenSSH server from starting in the future
   % touch /etc/ssh/sshd_not_to_be_run
3. Modify the Dropbear defaults file, set NO_START to 0 and 
   ensure DROPBEAR_PORT is set to 22.
   % editor /etc/default/dropbear
4. Restart the Dropbear server.
   % /etc/init.d/dropbear restart

See the Dropbear homepage for more information:
  http://matt.ucc.asn.au/dropbear/dropbear.html


Entropy from /dev/random
------------------------

The dropbear binary package is configured at compile time to read
entropy from /dev/random. If /dev/random on a system blocks when
reading data from it, client logins may be delayed until the client
times out. The dropbear server writes a notice to the logs when it
sees /dev/random blocking.  A workaround for such systems is to
re-compile the package with DROPBEAR_RANDOM_DEV set to /dev/urandom
in options.h.