are many services and software designed to blacklist bad web sites.
But, users can and do learn how to get around these "site-blockers,"
and there's a bad website born about every minute. Keeping up with all
the bad websites is next to impossible. A better option for
administrators (usually a parent) may be what's called whitelisting
on the account or the computer of a non-administrator (usually a
Whitelisting means blocking access to everything on the
Internet not already approved by the administrator. The computer is cut
off from everything on the Internet, except for what the
admin has in the whitelist. And it should go without saying; admins
should never let their son(s), daughter(s), husband or wife (whoever
they are intending to protect) see their administrator password.
For child's computer or account (especially homeschooled ones), you can download whitelist-buntu.txt from SavingUS as a base. To add to this list (or to look up any more sites), go to an IP lookup page such as this one or this one. Note: Some websites pull-in content from other servers and / or domain names. Examine the code (view the page source) of the web page / website to find all the addresses you'll want or need. Try searching the page source for "http."
Go to Menu --> System Tools --> LXTerminal
Backup the hosts file first:
sudo cp /etc/hosts /etc/hosts.old
Then edit the hosts file by typing (or copying and pasting):
sudo leafpad /etc/hosts
[Ctrl]+[A] to select all text in the whitelist-buntu.txt file, copy [Ctrl]+[C] then [Ctrl]+[A] to select-all in the hosts file and paste [Ctrl]+[V].
Backup the nsswitch.conf file:
sudo cp /etc/nsswitch.conf /etc/nsswitch.conf.old
then type: sudo leafpad /etc/nsswitch.conf to edit.
Find the hosts line and remove everything but
Save [Ctrl]+[S] and "X" out of the nsswitch.conf file.
Now everything except pre-approved sites are blocked.
Edit the hosts file again to allow access to additional websites (or
remove sites). Warning:
Google Chrome bypasses /etc/hosts, allowing unrestricted Internet
Run updates by reverting to the backup copy of the nsswitch file:
sudo cp /etc/nsswitch.conf.old /etc/nsswitch.conf
and saving [Ctrl]+[S].
Revert back again after updates are complete:
sudo leafpad /etc/nsswitch.conf
find the hosts line and again remove everything but
hosts: files and save [Ctrl]+[S].
OTHER INTERNET APPS
You may not want other applications with Internet access to remain once you've whitelisted. In that case, remove the following applications with the Lubuntu Software Center (LSC):
Go to Menu --> System Tools --> Lubuntu Software Center
Click on Installed Software
Provide your password and click OK
Transmission is particularly hard to remove. Doing it with LSC will only install QTransmission and vice-versa.
Instead, go to Menu --> System Tools --> LXTerminal
Then type (or copy and paste): sudo apt-get remove transmission-common -y && sudo apt-get purge transmission-common -y && sudo apt-get autoremove transmission-common -y