local forwarding(?)

local forwarding(?)

[cc]

Hi,

I finally got the bridge working and so far, 
things look ok.  

From the outside, I can goto the website.  That's
no problem.  The problem is for local machines
going to http://www.mydomain.com/, the firewall
doesn't seem to be redirecting it properly.
LAN users have to use http://192.168.11.10/ to
access the website instead of the www.mydomain.com.

I understand that the actual ip address skips
the firewall and goes directly to the machine.
From my boss' point of view(totally ignorant
that 192.168.11.10 = www.mydomain.com), he
doesn't like that.  So I'm hoping that he
can access (locally) www.mydomain.com.

So far my firewall script (the lines pertaining
to the www port) is as follows:

$IPTABLES -t nat -A PREROUTING -p tcp -i eth0 x.x.x.x \
      --dport 80 -j DNAT --to 192.168.10.11
$IPTABLES -A FORWARD -p tcp -i eth0 -d 192.168.10.11 \
      --dport 80 -j ACCEPT
$IPTABLES -A FORWARD -p tcp -i eth0 --dport 80 -j DROP

(I'm not entirely sure about that last item.  It looks
strangely invalid...but I could be wrong.  I don't
even think I should have that there.. am I right?)

If all my LAN ips are of the 192.168.10.0 host, 
and the web server is 192.168.10.11, how do I
get the LAN clients to go to www.mydomain.com and
have the firewall redirect the packets to 192.168.10.11?

As you probably can figure out, I'm a little confused. 

Any help appreciated

Re: local forwarding(?)

[Raymond Leach]

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On Fri, 2003-01-17 at 13:15, cc wrote:
> Hi,
> 
> I finally got the bridge working and so far, 
> things look ok.  
> 
> >From the outside, I can goto the website.  That's
> no problem.  The problem is for local machines
> going to http://www.mydomain.com/, the firewall
> doesn't seem to be redirecting it properly.
> LAN users have to use http://192.168.11.10/ to
> access the website instead of the www.mydomain.com.
> 
> I understand that the actual ip address skips
> the firewall and goes directly to the machine.
> >From my boss' point of view(totally ignorant
> that 192.168.11.10 = www.mydomain.com), he
> doesn't like that.  So I'm hoping that he
> can access (locally) www.mydomain.com.
> 
> So far my firewall script (the lines pertaining
> to the www port) is as follows:
> 
> $IPTABLES -t nat -A PREROUTING -p tcp -i eth0 x.x.x.x \
>       --dport 80 -j DNAT --to 192.168.10.11
> $IPTABLES -A FORWARD -p tcp -i eth0 -d 192.168.10.11 \
>       --dport 80 -j ACCEPT
> $IPTABLES -A FORWARD -p tcp -i eth0 --dport 80 -j DROP
> 
> (I'm not entirely sure about that last item.  It looks
> strangely invalid...but I could be wrong.  I don't
> even think I should have that there.. am I right?)
Depends on the default POLICY for your FORWARD chain. If the default
policy is to drop, then you don't need it.

> 
> If all my LAN ips are of the 192.168.10.0 host, 
> and the web server is 192.168.10.11, how do I
> get the LAN clients to go to www.mydomain.com and
> have the firewall redirect the packets to 192.168.10.11?
> 
Is the firewall the gateway to the internet for your users?

iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 80 -d
www.mydomain.com -j REDIRECT --to-destination 192.168.10.11:80

That should work (eth0 is your internal interface, right?) ...

Of course you also need the forwarding rules:

iptables -A FORWARD -p tcp --dport 80 -d 192.168.1.11 -j ACCEPT
iptables -A FORWARD -p tcp --sport 80 -s 192.168.1.11 -j ACCEPT

These are very wide open rules. You might want to add the -i and maybe
state checking...

> As you probably can figure out, I'm a little confused. 
> 
> Any help appreciated
> 
-- 
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Re: local forwarding(?)

[Narendra Prabhu. B]

On Fri, 17 Jan 2003, cc wrote:
> Hi,
>
> I finally got the bridge working and so far,
> things look ok.

Congrates ..

>
> From the outside, I can goto the website.  That's
> no problem.  The problem is for local machines
> going to http://www.mydomain.com/, the firewall
> doesn't seem to be redirecting it properly.
> LAN users have to use http://192.168.11.10/ to
> access the website instead of the www.mydomain.com.
>
> I understand that the actual ip address skips
> the firewall and goes directly to the machine.
> From my boss' point of view(totally ignorant
> that 192.168.11.10 = www.mydomain.com), he
> doesn't like that.  So I'm hoping that he
> can access (locally) www.mydomain.com.
>
> So far my firewall script (the lines pertaining
> to the www port) is as follows:
>
> $IPTABLES -t nat -A PREROUTING -p tcp -i eth0 x.x.x.x \
>       --dport 80 -j DNAT --to 192.168.10.11

There is no -d or -s option in the above command ....
Well, I guess that would be your public ip and the option would be -d in
that case.

Two things possible :-

	1> What IP address does the your dns resolve for www.mydomain.com
	   a)x.x.x.x
	   b)192.168.10.11

	try: $dig www.mydomain.com

	2> Check wheather eth0 is really your internal interface !! As you
	   have set up a bridge you can as well say the <bridge interface>
           <br0> .. But if you are really paranoid about the security then
	   try eth1 also.

	try: put separate rules for eth0 and eth1 and check which counter
		is incretmented... $iptables -nvL ....

> $IPTABLES -A FORWARD -p tcp -i eth0 -d 192.168.10.11 \
>       --dport 80 -j ACCEPT

Again, check the counters.

> $IPTABLES -A FORWARD -p tcp -i eth0 --dport 80 -j DROP
>
> (I'm not entirely sure about that last item.  It looks
> strangely invalid...but I could be wrong.  I don't
> even think I should have that there.. am I right?)

In my perseption, you dont want any other web site to be visited with this
rule.

>
> If all my LAN ips are of the 192.168.10.0 host,
> and the web server is 192.168.10.11, how do I
> get the LAN clients to go to www.mydomain.com and
> have the firewall redirect the packets to 192.168.10.11?
>
> As you probably can figure out, I'm a little confused.
>
> Any help appreciated

Let us know if it helps you.

Bye,
Narendra.

In the middle of difficulty..... lies Opportunity. (Albert Einstein)
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Narendra Prabhu. B             Free Software at its product-ive best.
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