iptables firewall for VPS on Debian Squeeze

flush-iptables.sh

#!/bin/sh
# This file will reset the firewall to allow everything. 
#
# Set the default policy
#
/sbin/iptables -P INPUT ACCEPT
/sbin/iptables -P FORWARD ACCEPT
/sbin/iptables -P OUTPUT ACCEPT
  
#
# Set the default policy for the NAT table
#
/sbin/iptables -t nat -P PREROUTING ACCEPT
/sbin/iptables -t nat -P POSTROUTING ACCEPT
/sbin/iptables -t nat -P OUTPUT ACCEPT
  
#
# Delete all rules
#
/sbin/iptables -F
/sbin/iptables -t nat -F
  
#
# Delete all chains
#
  
/sbin/iptables -X
/sbin/iptables -t nat -X
  
# End message

iptables.firewall.rules

*filter

#  Allow all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0
-A INPUT -i lo -j ACCEPT
-A INPUT -d 127.0.0.0/8 -j REJECT

#  Accept all established inbound connections
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

#  Allow all outbound traffic - you can modify this to only allow certain traffic
-A OUTPUT -j ACCEPT

#  Allow HTTP and HTTPS connections from anywhere (the normal ports for websites and SSL).
-A INPUT -p tcp --dport 80 -j ACCEPT
-A INPUT -p tcp --dport 443 -j ACCEPT

#  Allow SSH connections
#
#  The -dport number should be the same port number you set in sshd_config
#
-A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT

#  Allow ping
-A INPUT -p icmp -j ACCEPT

#  Log iptables denied calls
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7

#  Drop all other inbound - default deny unless explicitly allowed policy
-A INPUT -j DROP
-A FORWARD -j DROP

COMMIT

I dropped iptables.firewall.rules into /etc/ and then ran:

sudo iptables-restore < /etc/iptables.firewall.rules

Also set it up to start at boot.

flush-iptables.sh just sits in my home directory for usage when troubleshooting something.

It's good. Thanks!