Lately, I’ve spent quite a lot of time playing with my Kindle. The motivation was mostly its sloppiness – after having it for 1.5 year, my Kindle became very slow and unresponsive… I decided to factory reset it. And while doing it, I’ve checked if I maybe the jailbreak of newer firmware is possible (last time I’ve checked over a year ago it wasn’t).
To my big joy, I found these days it’s fairly easy to jailbreak any kindle by downgrading it’s firmware.
But this isn’t the focus of this post. Here I would like to share my experience with enabling ssh access to my Kindle. Why anyone would do that? Kindle is ARM-processor powered computer with Linux installed. So having SSH access, you can setup your Kindle to do lots of useful stuff. But about that, I’ll write in the next posts 😉
Here is how to proceed:

1. Jailbreak your Kindle
2. Install KUAL & Mobileread Package Installer (MrPI)
3. Install USBNetwork Hack
4. Create new user account in Kindle for SSH access

# get dev name from udev
dmesg | grep usb0

# bind
sudo ifconfig enp0s20u8 192.168.15.201

# telnet
telnet 192.168.15.244

# mount root with write access
mntroot rw

# create new user
mkdir -p /home
adduser USER

# make it root by changing USERID to 0 in <code>/etc/passwd</code> ie. 
USER:x:0:0:root,,,:/home/USER:/bin/sh

5. Start sshd and enable port 22 for SSH temporarily

This is only to check if SSH is possible. So far we didn’t make any serious changes 😉

/mnt/us/usbnet/sbin/sshd -f /mnt/us/usbnet/etc/sshd_config
iptables -A INPUT -p tcp --dport 22 -j ACCEPT

Now try to login to your Kindle by SSH. You can find its IP by executing ifconfig. Proceed only if SSH works for you.

6. Enable port 22 for SSH

# add below line to <code>/etc/sysconfig/iptables</code> to enable SSH access
-A INPUT -p tcp --dport 22 -j ACCEPT

7. Add sshd to upstart

Create new file /etc/upstart/sshd.conf

# ssh - OpenBSD Secure Shell server
#
# The OpenSSH server provides secure shell access to the system.

env LOGFILE=/tmp/ssh.log

description     "OpenSSH server"

start on dbus_ready
stop on stopping dbus

respawn limit 2 5
umask 022

pre-start script
    test -x /usr/sbin/sshd || { stop; exit 0; }
    test -e /etc/ssh/sshd_not_to_be_run && { stop; exit 0; }
    test -c /dev/null || { stop; exit 0; }
end script

script
    # if you used to set SSHD_OPTS in /etc/default/ssh, you can change the
    # 'exec' line here instead
    echo `date` "Starting sshd..." >> $LOGFILE 2>&1
    /mnt/us/usbnet/sbin/sshd -f /mnt/us/usbnet/etc/sshd_config >> $LOGFILE 2>&1
end script

8. Disable auto updates

mv /etc/uks /etc/uks.disabled

Now SSH should work after Kindle reboot 🙂

Enjoy!