Simple firewall script to start. Allows only 22 and 80 port.

simple_firewal.sh

# Exclui as regras ativas
iptables -t nat -F
iptables -t mangle -F
iptables -t filter -F

### Exclui cadeias customizadas
iptables -X

### Zera os contadores das cadeias
iptables -t nat -Z
iptables -t mangle -Z
iptables -t filter -Z

### Define a política padrão do firewall
iptables -P INPUT DROP
iptables -P OUTPUT ACCEPT
iptables -P FORWARD DROP

### Regras INPUT
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -p icmp --icmp-type 0 -j ACCEPT
iptables -A INPUT -p icmp --icmp-type 8 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j ACCEPT

### Regras OUTPUT
iptables -A OUTPUT -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

echo "Firewall Loaded!"