I want to block some https website like youtube.com, facebook.com.
I know that we can't block that using url rules. since the url is encrypted.
So I tried to block all DNS queries which contain the domain I want to filter. So I added the following rule:
iptables -A OUTPUT -p udp --dport 53 -m string --domain yahoo.com -j DROP
But the youtube keep running. But after some time of inactivity (about 15 min) youtube is blocked.
Are there some explanation?
How I can force youtube to be blocked immediately?