How to block some sites in Ubuntu 14.04.3?

Question

linux

Hello.
It is necessary to block certain sites, the browser is Mozilla. I tried to enter something like:
127.0.0.1 toster.ru in /etc/hosts and also in /etc/host.deny - it did not help. I also tried to do the following after the previously listed manipulations: sudo /etc/init.d/nscd restart . In the end, nothing helped.
Is there a solution to this problem? Preferably, without third-party programs, well, if it’s easier with them, then it’s possible with them.

Answer 1

Entries in /etc/hosts take effect immediately.
What does "didn't help" mean?