iptables Cheat Sheet

An iptables cheat sheet is useful for managing firewall rules on a Linux system. Here’s a iptables cheat sheet:

iptables Cheat Sheet

View Rules

View Current Rules:

iptables -L

View Detailed Rules:

iptables -L -v

Flush Rules

Flush All Rules:

iptables -F

Default Policies

Set Default Policies:

iptables -P INPUT <policy>
iptables -P OUTPUT <policy>
iptables -P FORWARD <policy>

• Replace <policy> with ACCEPT, DROP, or REJECT.

Create Rules

Allow Incoming Connections on a Port:

iptables -A INPUT -p tcp --dport <port> -j ACCEPT

Allow Outgoing Connections on a Port:

iptables -A OUTPUT -p tcp --dport <port> -j ACCEPT

Allow Incoming SSH:

iptables -A INPUT -p tcp --dport 22 -j ACCEPT

Delete Rules

Delete Rule by Number:

iptables -D INPUT <rule_number>

Port Forwarding

Forward Port 80 to 8080:

iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080

Stateful Firewall

Allow Related and Established Connections:

iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

Logging

Log Dropped Packets:

iptables -A INPUT -j LOG --log-prefix "Dropped: "

Save and Restore Rules

Save Rules:

iptables-save > /etc/iptables/rules.v4

Restore Rules:

iptables-restore < /etc/iptables/rules.v4

IPv6 Rules

View IPv6 Rules:

ip6tables -L

Allow Incoming SSH (IPv6):

ip6tables -A INPUT -p tcp --dport 22 -j ACCEPT

iptables Service

Start iptables Service:

service iptables start

Stop iptables Service:

service iptables stop

Restart iptables Service:

service iptables restart

Clear iptables Service

Clear and Reset iptables Service:

iptables -F

This cheat sheet provides basic commands for managing iptables rules on a Linux system. Always be cautious when configuring firewall rules, especially on production systems, to avoid accidental lockouts or security vulnerabilities.