How can one build a self-control app for Ubuntu? I can edit the /etc/hosts file using a script but the sudo user can still revert the changes. Please help.

Hello Jana :-). In a linux system the root is called the super user for a reason. The root can do anything. The only way that I know of to restrict is to put a password for the root user. Sudo can do anything on a linux system which can be dangerous or self destructive like deleting everything (happens more often than you think with rm -rf command). So your best bet is to lock your root with password. But most linux distributions don’t allow root users to be accessed. Instead they use sudo to get temporary root privileges. This can be controlled by setting which users are part of the sudo group (If your user account is not part of this group you cannot use sudo for temporary root privileges.) So if the user account is like a Guest account then I suggest you create limited accounts without sudo privileges. You cannot block sites through proxies generally. You may block proxies but it turns into a game of cat and mouse. The ultimate one would be Tor browser which nobody can do much about. The only fool proof solution is to block everything except what you want others to access (like only your company website or something). Blacklists to prevent some sites is difficult because there is so many alternatives. You will probably spend all your time on blocking new sites that people find to circumvent your control. tl;dr Limit the privilege of the user account to not be able to use sudo altogether. (This is what management does at my college for the lab systems with linux) NO sudo - Less hassle. The other one can be limited to a certain extent by firewalls but there is no 100% working solution except if the sole purpose of the network is to connect to an intranet. Thanking You, Ngcc Software Technologies. read less