Ban an IP address (IP address cannot be entered on the server)

# iptables -A INPUT -s 1.2.3.4 -j DROP

Ban an IP address (cannot be accessed from the server on the IP)

# iptables -A OUTPUT -s 1.2.3.4 -j DROP

Delete Rule by Chain and Number

# iptables -L --line-numbers

# iptables -D INPUT 3

Flush a Single Chain
Delete all of the rules in the INPUT chain, run this command

# iptables -F INPUT

Flush All Rules, Delete All Chains, and Accept All

# iptables -P INPUT ACCEPT
# iptables -P FORWARD ACCEPT
# iptables -P OUTPUT ACCEPT

# iptables -t nat -F
# iptables -t mangle -F
# iptables -F
# iptables -X