Iptables

Brief

iptables is statefull firewall util. Also it can use for redirect network trafic. Don't forget to read a manual man iptables

Require root permissions

Tips

Show all rules in all chains in filter table

# iptables -nL

Show all rules in INPUT chain in nat table

# iptables -nL INPUT -t nat

Add rule in INPUT chain in filter table

# iptables -A INPUT -i ens160 -p tcp -m tcp --dport 53 -j ACCEPT

Add a new rule in specify line in chain

# iptables -I INPUT 1 -i ens160 -p tcp -m tcp --dport 53 -j ACCEPT

Update a general policy(ACCEPT or DROP) for specific chain

# iptables -P INPUT DROP