Basic iptables starter script that only allow incoming SSH and ping

cfg-firewall.sh

#!/bin/bash
#
# basic iptables starter script that only allow incoming SSH and ping
#

# default actions
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT

# allow ping request
iptables -A INPUT -p icmp --icmp-type 8 -j ACCEPT

# allow SSH
iptables -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT

# allow all established
iptables -A INPUT -p tcp -m state --state ESTABLISHED,RELATED -j ACCEPT

# allow all localhost
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT