Mozilla Firefox is a quite handy browser compared to Iceweasel (default browser in Kali Linux). It has lot of plug-in features that Iceweasel lag. Sometimes, we find it difficulty while navigating through Iceweasel . Hence, I thought of installing Mozilla Firefox . To do this, you have to first un-install Iceweasel from Kali Linux or else it won't allow you to install Mozilla Firefox . Here are the step that I performed. 1. Open root terminal window and type apt-get remove iceweasel it removes iceweasel from the application menu 2. type echo -e "\ndeb http://downloads.sourceforge.net/project/ubuntuzilla/mozilla/apt all main" | tee -a /etc/apt/sources.list > /dev/null it adds repository for the installation 3. type apt-key adv --recv-keys --keyserver keyserver.ubuntu.com C1289A29 import the required gpg key 4. type apt-get update update the required package 5. type apt-get install firefox-mozilla-build install mozilla firefox on your sytem 6. type firef