Firewall VPN

What is a VPN

As a quick reminder, you can use a VPN for 3 things:

• Mask your source IP @

• Secure communication through the VPN server

• Access remote LAN

Of course you can combine some / all of these usages.

VPN firewall

Adjust the following to your own port, network ID and protocol:

IPTABLES=`which iptables`

INT_ETH=eth0
IP_LAN_ETH=`/sbin/ifconfig $INT_ETH | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}'`

INT_VPN=tun0
VPN_PORT="8080"
VPN_PROTOCOL="udp"
LAN_ADDRESS_VPN="172.16.60.0/24"

echo -e " "		
echo -e "------------------------"
echo -e " VPN configuration"
echo -e "------------------------"

echo " " 
echo -e "# VPN interface  : $INT_VPN"
echo -e "# VPN IP @       : $LAN_ADDRESS_VPN"
echo -e "# VPN port       : $VPN_PORT"
echo -e "# VPN protocol   : $VPN_PROTOCOL"
echo -e "-------------------------------------- "

# Allow devices communication $ETH0 <--> tun0
$IPTABLES -t nat -A POSTROUTING -s $LAN_ADDRESS_VPN -o $INT_ETH -j MASQUERADE
$IPTABLES -A FORWARD -s $LAN_ADDRESS_VPN -j ACCEPT

echo -e " ... Allow VPN connections"
$IPTABLES -A INPUT -p $VPN_PROTOCOL --dport $VPN_PORT -j ACCEPT
$IPTABLES -A OUTPUT -p tcp --dport $VPN_PORT -j ACCEPT

echo -e " ... Allow everything to go through VPN - all INPUT,OUTPUT,FORWARD"
$IPTABLES -A INPUT -i $INT_VPN -m state ! --state INVALID -j ACCEPT
$IPTABLES -A OUTPUT -o $INT_VPN -m state ! --state INVALID -j ACCEPT
$IPTABLES -A FORWARD -o $INT_VPN -m state ! --state INVALID -j ACCEPT

echo -e " ... Allow VPN network communication (required for client <> client comm.)"
$IPTABLES -A INPUT -s $LAN_ADDRESS_VPN -d $LAN_ADDRESS_VPN -j ACCEPT
$IPTABLES -A OUTPUT -s $LAN_ADDRESS_VPN -d $LAN_ADDRESS_VPN -j ACCEPT