ssh (or telnet) on the Kobo Glo

The Kobo Glo is a very nice device, but it lacks besides other things the ability to make screen shots. And it does not have an ssh or telnet server activated, so you cannot log onto this device and do changes deep in the system. This article describes how to install and setup an ssh server on the device, which in turn will also allow to do screen shots.

Warning: This is not for the faint of heart, you can easily can come into the situation that your device is unbootable. So keep a backup of the original firmware sd card, as described in this article. Also keep in mind that the descriptions here are for people who know how to operate a unix command line.

The following descriptions are based on this guide.

Overview

We first activate a telnet and ssh server on the device, then use telnet to log into the device and change a few things (root password, root home directory). After that ssh-ing into the device should work. After getting ssh to work, we disable the telnet again.

Preliminaries

As described in this article, the kobohack-j project ships an ssh server (dropbear) and a sftp server (openssh). So the best is to follow the upgrade guide given here.

If you do not want to install all of the kobohack parts, at least it is necessary to install the KoboRoot_hack.tgz by copying it to the directory KOBOeReader/.kobo/KoboRoot.tgz (where KOBOeReader refers to the mount point of your device). After that restart as usual.

Main procedure

In the following some items will be marked with (ON THE GLO) meaning that they should be carried out while logged into the device, not on your main computer. For those items I have also indicated a prompt that is given by the Kobo Glo: [root@(none) ~]# which should not be typed in.

1. Create a working directory KoboRoot and necessary sub-directories
   create a new directory KoboRoot (empty) and within that the following directories: etc and etc/init.d, i.e.,
   mkdir -p KoboRoot/etc/init.d
2. Getting hold of /etc/inittab:
   WARNING: the safest method is to extract the SD card, mount the rootfs, and copy the following file /etc/inittab. If this is not an option, one can use, on one’s own risk the file mentioned below. I don’t know how often Kobo changes these files, but I haven’t seen any change since I own the device. Put the file into the working directory KoboRoot/etc/inittab.
3. adaption KoboRoot/etc/inittab:
   one has to add two lines:
::sysinit:/etc/init.d/rcS2
::respawn:/usr/sbin/inetd -f /etc/inetd.conf.local
   If you got hold of the file from your device, just add these two lines, otherwise one could use the following content:
# This is run first except when booting in single-user mode.
::sysinit:/etc/init.d/rcS
::respawn:/sbin/getty -L ttymxc0 115200 vt100
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r
::restart:/sbin/init
::sysinit:/etc/init.d/rcS2
::respawn:/usr/sbin/inetd -f /etc/inetd.conf.local
4. creation of KoboRoot/etc/init.d/rcS2
   this is a new file with the following content:
#!/bin/sh
mkdir -p /dev/pts
mount -t devpts devpts /dev/pts
/usr/sbin/inetd /etc/inetd.conf.local
   make sure that this file is also executable
chmod a+x KoboRoot/etc/init.d/rcS2

5. creation of KoboRoot/etc/inetd.conf.local
   Create a the inetd.conf.local file with the following content:
22 stream tcp nowait root /bin/dropbearmulti dropbear -i -B
23 stream tcp nowait root /bin/busybox telnetd -i
6. create a new KoboHack.tgz
   tar -cvzf KoboRoot.tgz -C KoboRoot .
7. copy new KoboRoot.tgz to KOBOeReader/.kobo/
8. reboot reader, it should show “Updating …”
9. Turn on Wifi on the Kobo and find IP address
   Go to Settings – Connect and after this is done, go to Settings – Device Information where you will see something like
IP Address:     192.168.1.NN
   (numbers change!)
10. telnet into your device
    telnet 192.168.1.NN
    it will ask you the user name, enter “root” (without the quotes) and no password
11. (ON THE GLO) change home directory of root
    edit /etc/passwd with vi and change the entry for root by changing the 6th field from: “/” to “/root” (without the quotes). After this procedure the line should look like
    root::0:0:root:/root:/bin/sh
    don’t forget to save the file
12. (ON THE GLO) create ssh keys for dropbear
    [root@(none) ~]# mkdir /etc/dropbear
[root@(none) ~]# cd /etc/dropbear
[root@(none) ~]# dropbearkey -t dss -f dropbear_dss_host_key
[root@(none) ~]# dropbearkey -t rsa -f dropbear_rsa_host_key
13. (ON YOUR PERSONAL COMPUTER) check that you can log in with ssh
    ssh root@192.168.1.NN
    You should get dropped into your device again
14. (ON THE GLO) log out of the telnet session (the first one you did)
    [root@(none) ~]# exit
15. (ON THE GLO) in your ssh session, change the password of root
    [root@(none) ~]# passwd
    you will have to enter the new password two times. Remember it well, you will not be easily able to recover it without opening your device.
16. (ON THE GLO) disable telnet login
    edit the file /etc/inetd.conf.local on the GLO (using vi) and remove the telnet line (the line starting with 23).
17. restart your device

From now on you should always be able to log into your device with ssh using a password.