Howto block all except certain web site
I have a computer lab that I want to block all sites except certain site?
Thats called white listing.
Don't know that you necessarily need another app. Why not identify the remote sites IP range and then add a 'block if not' rule to the LAN adapter.
Identify the range simply by pinging from a command prompt, you can put the result into a who is IP search to get the full range although the single IP returned should be sufficient.
You can use the URL domain in rules, e.g. www.allowedsite.com
Then pfSense will find (and recheck every 5 minutes) the corresponding IP address(es) and put them in a table in pf. That way if the site does change its IP address, or have multiple addresses, that will be coped with.