Just create a firewall profile that blocks everything except
dns and set your update mirror to one that only accepts the
apt-get install gufw
Now go to the dash, and type
firewall and click the sole icon remaining and you'll see:
Begin warning: From now on, until you see End warning, you will not have access to the Internet!
- Take the "public" profile (or another one you're currently now using) and set everything to "reject" (as in the picture above)
- Click the + below "rules" and click on the "Simple" tab and fill out the screen as follows:
and press Add
Then fill out the screen as follows:
and press Add, then Close
Your rules section should now look like this:
- Mirror config
In the Netherlands, there is only one mirror that supports ftp only:
Ftpserv-tudelft-nl, for all other countries, look here for the full list and choose your own.
Now go to the dash again and type
Software Updater and again, click the sole icon available, click Settings, the "Ubuntu Software" tab, "Download from:" and choose Other, take the country of your choice and the server of your choice:
And voilà: you can only surf the Internet and nothing else can happen any more! No updates, no email, no Skype, no FTP, no HTTPS, no nothing! Only DNS look-ups and web surfing
If you would like to have more then the absolute minimal available, have a look at IANA assigned port numbers
and add any other protocol numbers you would need.
To revert back to normal use: just open the
firewall in the dash again, Click on Public and then click on Home and you're back to where you were!