Just try this.
To use it:
- Create a file named /etc/init.d/firewall
- Copy and paste the script into it and save
- Edit the ALLOWED variable with port numbers you want to allow, default is ports 22 (SSH) and 80 (HTTP)
- Execute:
touch /usr/local/etc/whitelist.txt && touch /usr/local/etc/blacklist.txt
- Edit the whitelist/blacklist files if you want
- Execute:
chmod 755 /etc/init.d/firewall
- Execute:
chkconfig --add firewall && chkconfig firewall on
The script:
#!/bin/bash
# chkconfig: 345 30 99
# description: Starts and stops iptables based firewall
## List Locations
#
WHITELIST=/usr/local/etc/whitelist.txt
BLACKLIST=/usr/local/etc/blacklist.txt
#
## Specify ports you wish to use.
#
ALLOWED="22 80 25"
#
## Specify where IP Tables is located
#
IPTABLES=/sbin/iptables
##
#DO NOT EDIT BELOW THIS LINE
###
RETVAL=0
# To start the firewall
start() {
echo "Setting up firewall rules..."
echo 'Allowing Localhost'
#Allow localhost.
$IPTABLES -A INPUT -t filter -s 127.0.0.1 -j ACCEPT
#
## Whitelist
#
for x in `grep -v ^# $WHITELIST | awk '{print $1}'`; do
echo "Permitting $x..."
$IPTABLES -A INPUT -t filter -s $x -j ACCEPT
done
#
## Blacklist
#
for x in `grep -v ^# $BLACKLIST | awk '{print $1}'`; do
echo "Denying $x..."
$IPTABLES -A INPUT -t filter -s $x -j DROP
done
#
## Permitted Ports
#
for port in $ALLOWED; do
echo "Accepting port TCP $port..."
$IPTABLES -A INPUT -t filter -p tcp --dport $port -j ACCEPT
done
for port in $ALLOWED; do
echo "Accepting port UDP $port..."
$IPTABLES -A INPUT -t filter -p udp --dport $port -j ACCEPT
done
$IPTABLES -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
$IPTABLES -A INPUT -p udp -j DROP
$IPTABLES -A INPUT -p tcp --syn -j DROP
RETVAL=0
}
# To stop the firewall
stop() {
echo "Removing all iptables rules..."
/sbin/iptables -F
/sbin/iptables -X
/sbin/iptables -Z
RETVAL=0
}
case $1 in
start)
stop
start
;;
stop)
stop
;;
restart)
stop
start
;;
status)
/sbin/iptables -L
/sbin/iptables -t nat -L
RETVAL=0
;;
*)
echo "Usage: firewall {start|stop|restart|status}"
RETVAL=1
esac
exit $RETVAL
