I am trying to install Webmin, on Ubuntu 14.04 LTS, I have gotten as far as having webmin showing up in software center but when I click install I get the error message "This requires installing packages from unauthenticated sources". I have googled that message and have tried about four different solutions but they don't seem to help the problem. Does any one else have any other solutions?
Regarding your issue please follow the below steps and check.
Run below command to edit the source file:
sudo vi /etc/apt/sources.list
Press i on keyboard to start editing the file and add this line into the end:
deb http://download.webmin.com/download/repository saucy contrib
Press Esc to exit edit. Shift + : and followed by wq to save the changes.
Now execute command to download and install the key:
wget -q http://www.webmin.com/jcameron-key.asc -O- | sudo apt-key add -
After that, you can always use below commands to install the latest version of Webmin:
sudo apt-get update sudo apt-get install webmin
Finally in your client’s web browser go to the webmin login page and check