Didj Install Dropbear

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Summary

Dropbear is a relatively small SSH 2 server and client. This can be used for accessing the Didj with out a UART connection. You will have to disable the USB Mass Storage driver, but you can still access that directory from with in the Didj itself.

Software Needed

Dropbear


Compiling

Untar the file and go into the resulting directory.

On Host:

$ tar -xvzf dropbear-0.52.tar.gz
$ cd dropbear-0.52


Optional Edit options.h in the dropbear source directory.


You will need to Enable Networking on your Didj. This tutorial uses the IP addresses and user name from that tutorial, change accordingly if you've used different values.

And Set up the Build Environment Variables if they haven't already been set in your terminal from building the kernel in the last step.

Set up the CC variable and then configure the compilation. (In this example we add directives to disable zlib, syslog, and lastlog)

On Host

$ export CC=arm-linux-uclibcgnueabi-gcc
$ ./configure --host=arm-linux-uclibcgnueabi --disable-zlib --disable-syslog --disable-lastlog

Compile Dropbear (In this example, we create a single statically-linked executable that, like Busybox, encompases a number of programs.)

On Host

$ make PROGRAMS="dropbear dbclient dropbearkey dropbearconvert scp" STATIC=1 MULTI=1

To reduce the size of the resulting binary file, strip the symbols:

On Host

$ arm-linux-uclibcgnueabi-strip dropbearmulti

Installing

Mount the Didj drive on your host PC. Make sure the USB cable is connected between your PC and Didj.

On the Didj

# usbctl -d mass_storage -a enable
# usbctl -d mass_storage -a unlock

The Didj should then automount allow you access to copy files over.

Copy dropbearmulti to the mounted Didj directory (this is the /Didj directory on the device), and then unmount the Didj.

On Host

$ cp dropbearmulti /mnt/Didj
$ umount /mnt/Didj

Then, on the Didj console, disable mass_storage (which results in /Didj mounting on the device)

On Didj

# usbctl -d mass_storage -a disable

Move dropbearmulti to its final home, and create symlinks for the dropbear programs.

On Didj

# mount -o remount, rw /
# cp /Didj/dropbearmulti /bin
# cd /bin
# ln -s dropbearmulti dropbear
# ln -s dropbearmulti dbclient
# ln -s dropbearmulti dropbearkey
# ln -s dropbearmulti dropbearconvert
# ln -s dropbearmulti scp

Lastly, create the default directory for the encryption keys, and then generate the keys:

On Didj

# mkdir /etc/dropbear
# dropbearkey -t rsa -s 1024 -f /etc/dropbear/dropbear_rsa_host_key
# dropbearkey -t dss -f /etc/dropbear/dropbear_dss_host_key

Running

Now launch dropbear...

On Didj

# dropbear -a

And SSH in from your host! (assumes you have created a user named 'didj')

On Host

$ ssh didj@10.0.0.2

You should now be logged in to your home directory.