firewall settings that only allows ssh and web access

firewall.sh

#!/bin/sh

# Flushing all rules
iptables -F
iptables -X

# Setting default filter policy
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP

# Allow unlimited traffic on loopback
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT
 
# Allow incoming ssh only
iptables -A INPUT -m state --state NEW -p tcp --dport 22 -j ACCEPT

# Allow web traffic
iptables -A INPUT -m state --state NEW -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -m state --state NEW -p tcp --dport 443 -j ACCEPT

# make sure nothing comes or goes out of this box
iptables -A INPUT -j DROP
iptables -A OUTPUT -j DROP

largely stolen from http://www.cyberciti.biz/tips/linux-iptables-4-block-all-incoming-traffic-but-allow-ssh.html and http://www.cyberciti.biz/faq/linux-web-server-firewall-tutorial/