Why doesn't the url blocking rule work?

Question

linux

You need to block the youtube url, there is an ubuntu 16 gateway, there is a rule on it in iptables:

iptables -A FORWARD -m string --string "youtube.com" --algo kmp --to 65535 -j DROP

It doesn't work, why? Thank you

Answer 1

Probably because you need to block youtube, and the rule says --string "vkontakte.ru" ? :-)

Answer 2

So?
iptables -A INPUT -m string --string "youtube.com" --algo kmp --to 65535 -p tcp --dport 80 -j DROP
iptables -A OUTPUT -m string --string "youtube.com" -- algo kmp --to 65535 -p tcp --dport 80 -j DROP
AND for https
iptables -A INPUT -m string --string "youtube.com" --algo kmp --to 65535 -p tcp --dport 443 - j DROP
iptables -A OUTPUT -m string --string "youtube.com" --algo kmp --to 65535 -p tcp --dport 443 -j DROP
UPD: I checked, it always goes to https, the last two rules are enough :)