View source for User:Thomax:nat-loopback

== NAT Loopback Configuration on OpenWRT ==


Well, first is this little script, which should be placed in ''/etc/firewall.user'':

<pre>
# get the WANIP from the ppp0 interface
WANIP=`ifconfig ppp0 | awk '/inet addr/ {split ($2,A,":"); print A[2]}'`

# my lan ip
LANIP = 192.168.1.100

nat_loopback() {         
        iptables -t nat -A prerouting_rule -d $WANIP -p $3 --dport $1 -j DNAT --to $2
        iptables -A forwarding_rule -p $3 --dport $1 -d $2 -j ACCEPT
        iptables -t nat -A postrouting_rule -s 192.168.1.0/24 -p $3 --dport $1 -d $2 -j MASQUERADE
}                                                                                             


# thats for a local apache (yepp, i have a local web server..)
nat_loopback 80 $LANIP tcp

# http_listen_port from the OpenSim.ini
nat_loopback 9000 $LANIP tcp         

# and the udp port of the region (RegionConfig.ini)
nat_loopback 19010 $LANIP udp
</pre>


And just because I have a dynamic IP address I need to be sure that the firewall rules get reloaded on each new PPPoE connect. Thats why I created the script ''/etc/ppp/ip-up.d/connect.sh''
which looks like this:

<pre>
#!/bin/sh

# Put stuff here you need todo just when your router reconnects to the provider

/etc/init.d/firewall reload
</pre>


Thats what I've additionally done beside the normal LuCI settings on my openWRT router, which is an asus wl-500gP (with this nice two USB slots :-)

Let me know if it helps you too...

thomax