The only current version of Ubuntu this works for is 12.04 and the repos haven't been updated since 2013. Don't use it.

For 14.04+, please see the second answer.

Copy the following Kali repositories:

deb http://ppa.launchpad.net/wagungs/kali-linux2/ubuntu YOUR_UBUNTU_VERSION main 

deb-src http://ppa.launchpad.net/wagungs/kali-linux2/ubuntu YOUR_UBUNTU_VERSION         main 

deb http://ppa.launchpad.net/wagungs/kali-linux/ubuntu YOUR_UBUNTU_VERSION main 

deb-src http://ppa.launchpad.net/wagungs/kali-linux/ubuntu YOUR_UBUNTU_VERSION main 

Replace the text YOUR_UBUNTU_VERSION based on your Ubuntu version.

• Ubuntu 12.04: precise


• Ubuntu 12.10: quantal


• Ubuntu 13.04: raring

Assuming that you are using Ubuntu 13.04, your repositories would be

deb http://ppa.launchpad.net/wagungs/kali-linux2/ubuntu raring main

deb-src http://ppa.launchpad.net/wagungs/kali-linux2/ubuntu raring main

deb http://ppa.launchpad.net/wagungs/kali-linux/ubuntu raring main

deb-src http://ppa.launchpad.net/wagungs/kali-linux/ubuntu raring main 

Note: If you're an Ubuntu 14.04 user, you can use raring, as Trusty version of Kali repositories are not released

Update sources

Open your sources using the command

sudo -H gedit /etc/apt/sources.list.d/kali-tools.list

Now, gedit editor will open the file kali-tools.list. Paste the above code at the end of your file and Save.

Copy the PGP Key

Copy the Key below and save it as key.pgp text file in your desktop.

-----BEGIN PGP PUBLIC KEY BLOCK-----

 Version: SKS 1.1.4

 Comment: Hostname: keyserver.ubuntu.com



 mI0ET324YwEEANbSlISrOlAGjxgFRxiN6jk0JIl/vxQ8lapRdxZ4DHDAQdXbX4AuigMBkP5e

 sOxhMpDnkgMRtEVpaBMdQheA0/431pPQYqkr3jdeZw5JS5opiyJ4qr/QrcoSFHSluEkWkbZ6

 RYOkA25vW31KK2FB2LQVRYk580llXAVgIUznm2ATABEBAAG0GExhdW5jaHBhZCBQUEEgZm9y

 IHdhZ3VuZ4i4BBMBAgAiBQJPfbhjAhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRAb

 IuuNj9/bVxabBADSGN8cp+hqkdZqwq263wdz/UGsiuB1bCrH06/HznC/ZC5rjfH3aQ1Dwwag

 zYCrSD3c0cKNAqD10009N76RMlzZBH8kKL9khH3zPL/k4/lYuVP7y6NKFbBsnawEUc0mWcCa

 mH4ScTdWWPXP/mOQiUUjnQ1bZhzpcbQOb+hEUAqExg==

 =fJ+8

 -----END PGP PUBLIC KEY BLOCK-----

Add PGP Key in apt

Open terminal and type

cd Desktop

sudo apt-key add key.pgp

If your key addition is successful, you will see Ok.

Now update your apt-get repositories using the command

sudo apt-get update

Install Synaptic Package Manager

Use the command

sudo apt-get install synaptic

If you already have Synaptic installed, you may skip this step.

Install Kali Tools

Now open Synaptic Package manager and click on Origin. You can see 2 Kali repositories by names

LP-PPA-wagungs-kali-linux/raring

LP-PPA-wagungs-kali-linux2/raring

Click on the repositories and install the Tools from the list.