How to block port 80 on ubuntu

I just block my port 80 by using this CLI

iptables -A INPUT -j DROP -p tcp --destination-port 80 -i eth0

The code above will drop all tcp packets coming into your Linux computer on device eth0 on port 80. If your Internet connection runs through a device other than eth0, go ahead and make the adjustment.

To remove the iptables rule use the following code:

iptables -D INPUT -j DROP -p tcp --destination-port 80 -i eth0

credit to : foogazi