iptables -t filter -A INPUT -i eth0 -p tcp --dport 80 -j DROP or iptables -t filter -A INPUT -i eth0 -p tcp -s 1.2.3.4 --dport 80 -j DROP
iptables -t filter -A INPUT -i eth0 -p tcp --dport 80 -j DROP or iptables -t filter -A INPUT -i eth0 -p tcp -s 1.2.3.4 --dport 80 -j DROP