firewall startup script

[Felix Bauer <felixathome@xxxxxxx>]

Hi,

if got a question about my script for my router-configuration. It should 
enable ip4warding, masquerade my local hosts,
allow my local hosts everything and open some ports which should be 
external available but if I run this script
it kinda stops after masquerading (I can read the output on the console 
but then everything is freezed since the local
ports aren't open anymore and not reopend by the script). Is there any 
logical error I missed?

<script>
#!/bin/bash
#** $Id$
#**
#** Firewall-startup script
#**

#** variables
iptables="/sbin/iptables"
localnet="192.168.0.0/24"
worldports="21 22 53 80"


case $1 in
   start)
   #** enable IP-forwarding
    echo "Enabling IP-Forwarding"
    echo "1" > /proc/sys/net/ipv4/ip_forward

    #** flush old chains
     echo "Flushing old rules"
     $iptables -F INPUT
     $iptables -F OUTPUT
     $iptables -F FORWARD
     $iptables -t nat -F PREROUTING
     $iptables -t nat -F POSTROUTING
     $iptables -t nat -F OUTPUT

    #** allow localnet everything
     echo "Creating rule for local network"
     $iptables -A INPUT -s localhost -d localhost -j ACCEPT
     $iptables -A INPUT -p tcp -s $localnet -j ACCEPT
     $iptables -A INPUT -p udp -s $localnet -j ACCEPT

    #** setup Masquerading
     echo "Creating rule for Masquerading"
     $iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE

    #** opening ports
     echo "Opening ports:"
     $iptables -A INPUT -p icmp -j ACCEPT

     for port in $worldports
      do
       echo " - $port"
       $iptables -A INPUT -p tcp --dport $port -j ACCEPT
       $iptables -A INPUT -p udp --dport $port -j ACCEPT
      done

    #** Allow all outgoing packets to be not filtered
     $iptables --policy OUTPUT ACCEPT

    #** Drop everything else
     $iptables -A INPUT -j DROP
   ;;
   stop)
   ;;
   *)
   echo "Usage: $0 { start | stop }"
   ;;
   esac
exit 0
</script>

thx a lot
fe