Is there a way to ban adult websites?
A country blocks access to adult websites based on the IP address. The person still access those adult websites by using a proxy like "tor browser", "Psiphon" browser plugins "browsec", etc.
Is there a solution to ban access to adult websites even if the person uses a proxy?
Best Answer
You cannot block all possible workarounds to access a certain webserver but you may use a layered approach to make it very hard for the average end user to access said blocked content
A policy as stated above may be implemented by using a modern firewall that is capable of L7 firewalling (e.g. Cisco FirePower, Palo Alto Networks, Checkpoint, Sophos, etc. etc.)
I have only listed a few vendors for reference. There are many solutions for your problem and a firewall capable of deep packet inspection may be the best fit to solve your issue.