Howto APT behind a proxy server

If your machine is behind a proxy server your apt-get install will not work properly
in this case you have to open a terminal and type the following command
I am assuming that you have no username and password for using internet then use this commands

export http_proxy=http://192.168.0.2:3128/ (replace the IP address and port with  your

export ftp_proxy=http://192.168.0.2:3128(replace the IP address and port with your


if you have username and password use

export http_proxy=http://username:password@192.168.0.2:3128/
export ftp_proxy=http://username:password@192.168.0.2:3128/

OR

Create or Edit /etc/apt/apt.conf

Add the Following 

Acquire::http::proxy "http://:/";
Acquire::ftp::proxy "ftp://:/";
Acquire::https::proxy "https://:/";