Prerequisites

• You have a jailbroken Kindle. If not, you can refer to this post.
• Both KUAL and MRPI are installed. If not, refer to this post.

Installing

1. Go to the Snapshots page on MobileRead.
2. Under the right product category, find the USBNetwork Hack. Download the .tar.xz file.
3. Extract the downloaded file, select the correct Update_usbnet_*.bin file. There are multiple update files for different devices, so make sure you select the correct one!
4. Connect your Kindle to your computer via USB cable. Confirm it’s in USB Drive Mode.
5. Place the selected file in Step 3 in /mrpackage/ under your Kindle’s root folder.
6. Disconnect Kindle from the computer.
7. Go to KUAL--Helper--Install MR Packages, install the USBNetwork.

SSH via USB

After installing by default, this is the only possible way to connect. Depending on the OS, some of the following steps can differ:

1. Turn on the SSH server on the Kindle by typing ;un in the search bar then press Enter. This will start the server with its IP as 192.168.15.244 which expects a incoming connection from 192.168.15.201.
2. Configure the network on the client side:
   • macOS: System Settings--Network--RNDIS/Ethernet Gadget--Details--TCP/IP
     • Configure IPv4: Manually
     • IP Address: 192.168.15.201
     • Subnet Mask: 255.255.255.0
     • The red dot indicating the network should turn green
   • Linux: ifconfig usb0 192.168.15.201
   • Windows: Please check the Windows section of this post.
3. Connecting to server: ssh root@192.168.15.244. No password, so just press Enter.

SSH via WiFi

Now that you have the remote access to your Kindle, you can also turn on the SSH connection via WiFi. There are two reasons that you might want to do this:

1. The connecting is easier as you don’t have to do the plugging and unplugging.
2. It might be easier for the debugging as the Kindle being charged while connecting via USB might influence some system behaviors which make the debugging difficult.

This can be enabled by:

1. Change USE_WIFI option to TRUE for /mnt/us/usbnet/etc/config
2. Restart SSH server in KUAL

Then disconnecting the Kindle from the computer, the server can be accessed by ssh root@YourKindle'sIP (usually it’s 192.168.0|1.x).

Some tidying up

Some of the below are not closely related to SSH but they become a problem once SSH connection is possible.

Start SSH service on boot

1. SSH into Kindle
2. touch /mnt/us/usbnet/auto

Show logs while starting Kindle

1. SSH into Kindle
2. touch /mnt/us/usbnet/verbose

This will show some logs at the bottom of the screen while Kindle is starting.

Give Kindle a static IP

If you want to use SSH via WiFi consistently, it is recommended to use DHCP to give Kindle a static local IP. This can be achieved by a router.

Set a password for root user

This is a major security risk with incoming SSH connection. Essentially without password anyone within your LAN has the access to your Kindle.

1. SSH into Kindle
2. passwd, then enter your new password

Attention, next time when you want to Ssh into your Kindle, you should use the newly-set password.

Use pub key authentication

This is more convenient and securer than a password login. The steps are below:

1. Run ssh-keygen on your client machine. Enter the name you would like it to have. In the end it gives you a private key xxx and a public key xxx.pub.
2. Copy the xxx.pub to /mnt/us/usbnet/etc/ using scp, rename it to authorized_keys
3. Copy xxx to the .ssh folder on your client machine.

Now you should be able to connect your Kindle with pub key authentication.

Some more tweaks

Similar as the SSH service on another Linux machine, there exists a sshd config file in Kindle’s system (/mnt/us/usbnet/etc/sshd_config). There you can do things like turning off password login, restrict login IPs and adjusting port etc.

Closing remarks

Connecting to Kindle via SSH to be honest is not that straightforward comparing to other Linux machines. However, this is not all impossible by following the previously mentioned steps. This exposes the system files to us and make possible further tweaking of the system via scripting.

Why KUAL and MRPI?

Many extensions you can install after jailbreaking the Kindle depends on them, e.g., enabling SSH on the Kindle.

Prerequisites

You have a Kindle which is already jailbroken. If not, refer to this post.

KUAL

It can be installed by following these steps:

1. Go to the Snapshots page on MobileRead, there under the KUAL & KUAL extensions section, you can download the file for the bullet KUAL.
2. Extract the downloaded .tar.xz file.
   • If your Kindle runs firmware 5.x, select file KUAL-KDK-2.0.azw2
   • If your Kindle runs an older firmware, select file KUAL-KDK-1.0.azw2
3. Connect your Kindle to your computer via USB cable. Confirm it’s in USB Drive Mode.
4. Copy the selected file into /documents of your Kindle drive.
5. Disconnect your Kindle and a new book should appear on your home screen.
6. Tap on the book, you enter KUAL, meaning it’s successfully installed.

MRPI

It stands for MobileRead Package Installer, which is an extension of KUAL. You can install many packages using MRPI and it makes your life easier according to MobileRead.

The steps to install are:

1. Go to the Snapshots page on MobileRead, there under the KUAL & KUAL extensions section, you can download the file for the bullet MR Package Installer.
2. Extract the downloaded .tar.xz file.
3. Connect your Kindle to your computer via USB cable. Confirm it’s in USB Drive Mode.
4. Copy all extracted files in Step 2 to the root folder of your Kindle.
5. After disconnecting your Kindle from the computer, you can confirm it’s successfully installed by going to KUAL, there a new helper menu should appear.

Concluding remarks

With these preparations done, many extensions can be installed, which will be shown in the next post.

Downgrading:

This is mainly based on this post on MobileRead.

The firmware on my KW1 is 5.6.6.1 which doesn’t seem to be jailbreaking ready according to MobileRead. Thus, it needs to be downgraded to a supported version of firmware (5.3.3 before applying jailbreaking. The steps are:

1. Download 5.3.3 firmware here
2. Disable your Kindle’s WiFi by turning on airplane mode
3. Connect your Kindle to your computer through USB cable, you should see a wallpaper displaying USB Drive Mode
4. Once connected, copy the download firmware (.bin) to the root of your connected Kindle
5. keep connected, wait for 2 minutes
6. Press and hold power button until Kindle is restarted, now it should be installing the firmware.
7. You can confirm the downgrading after the reboot by going to: Menu--Settings--Menu--device info

If you see 5.3.3 for the firmware, congrats! You have successfully downgraded the firmware on your Kindle Paperwhite 1.

Jailbreaking

This is mainly based on this post on MobileRead.

Now you are on 5.3.3, you can jailbreak your Kindle by following these steps:

1. Download K5 JailBreak (5.0.x - 5.4.4.2) file from Snapshots page on MobileRead.
2. Connect your Kindle to your computer by USB, make sure it’s in USB drive mode
3. Extract the content of the downloaded tar.xz file (not the folder JailBreak itself) to the root folder of your Kindle.
4. Update the Kindle system as you normally will by going to: Menu--Settings--Menu--Update your Kindle. The system will not reboot. Instead, after a few seconds the following text appear **** JAILBREAK ****. This will only appear once.
5. Restart your Kindle by: Menu--Settings--Menu--Restart.

Concluding remarks

Jailbreaking your Kindle opens many new ways for you to use your Kindle. But before going into, several preparations need to be done on the Kindle, which will be shown in another post.