If I want to add
INPUT firewall rules in my server suggestions I see is to do the following (port 80 here, but could be any other service's well known port)
iptables -A INPUT -p tcp --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
How is this different from
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
ie: what is the benefit checking the connection state in the
INPUT chain since the server has to serve any request on port 80 ?