On Wednesday 10 July 2002 2:54 pm, Mark Ayad wrote:

> I have a problem with the following Firewall Script which works fine apart
> from when I try to INTERNALLY connect to the webserver 192.168.0.3:80
> using the public IP which if I'm right should be the same as $EXTIF. The
> internal machine I'm launching the request from is actually the webserver
> (but that shouldn't matter).
>
> I know I'm missing a line from what I read in
> http://netfilter.samba.org/unreliable-guides/NAT-HOWTO/NAT-HOWTO.linuxdoc-1
>0 .html and I've tried nearly every combination I can think of except the
> one that works that is.
>
> So whats the missing line ?
>
> $IPTABLES -A INPUT -p tcp --syn --destination-port 80 -j ACCEPT
> $IPTABLES -A INPUT -p tcp --syn -j DROP
>
> $IPTABLES -A FORWARD -i $EXTIF -o $INTIF -j ACCEPT
> $IPTABLES -A FORWARD -i $INTIF -o $EXTIF -j ACCEPT
> $IPTABLES -A FORWARD -j LOG
>
> $IPTABLES -t nat -A PREROUTING -p tcp -i eth0 --dport 80 -j
> DNAT --to-destination 192.168.0.3:80
>
> $IPTABLES -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE

This one looks a bit odd to me, even though I've written it myself, but I 
think it should do the trick:

$IPTABLES -t nat -A POSTROUTING -o $INTIF -i $INTIF -j MASQUERADE

If it doesn't, then just use the standard version:

$IPTABLES -t nat -A POSTROUTING -o $INTIF -s a.b.c.d/n -j MASQUERADE

where a.b.c.d/n is your internal network range.

 

Antony.

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