Install Webmin via apt-get on Ubuntu Server 12.04

Firstly we need to establish what kind of network scenario you have. If you are going out to the internet via a proxy server, start from point number 1, else you can start on point 2.

1: Open /etc/environment using vi (or your editor of choice), and add the following:

http_proxy=”http://myproxy.server.com:8080/”
https_proxy=”http://myproxy.server.com:8080/”
ftp_proxy=”http://myproxy.server.com:8080/”
no_proxy=”localhost,127.0.0.1,localaddress,.localdomain.com”
HTTP_PROXY=”http://myproxy.server.com:8080/”
HTTPS_PROXY=”http://myproxy.server.com:8080/”
FTP_PROXY=”http://myproxy.server.com:8080/”
NO_PROXY=”localhost,127.0.0.1,localaddress,.localdomain.com”

If your proxy requires authentication, you can include a global username and password like this:

http://username:password@myproxy.server.com:8080/

2: Edit the /etc/apt/sources.list file on your system and add the lines :

deb http://download.webmin.com/download/repository sarge contrib
deb http://webmin.mirror.somersettechsolutions.co.uk/repository sarge contrib

3: Fetch and install the GPG key with which the repository is signed, with the commands :

cd /root
wget http://www.webmin.com/jcameron-key.asc
apt-key add jcameron-key.asc

If you get a Permission Denied error when accessing the /root directory, do the following:

sudo -s

cd /root

4: You will now be able to install with the commands: 

apt-get update
apt-get install webmin

All dependencies should be resolved automatically.