The Ubuntu package management tool (i.e. dpkg and apt) ensure package consistency and authenticity by requiring that distributors sign packages with GPG keys. Issue the following command to import the 10gen public GPG Key:
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv 7F0CEB10
Create a /etc/apt/sources.list.d/10gen.list file and include the following line for the 10gen repository.
deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen
Now issue the following command to reload your repository:
sudo apt-get update
Issue the following command to install the latest stable version of MongoDB:
sudo apt-get install mongodb-10gen
When this command completes, you have successfully installed MongoDB! Continue for configuration and start-up suggestions.