On Fri, May 10, 2002 at 01:29:21AM +0100, alan barrow wrote:

> I have been using iptables-netfilter for a while and wish to clarify in
> my mind for once how to do the following. 
> 
> Scenario: An iptables firewall has 2 interfaces, which are a public and
> a private interface, for simpilicty's sake. Behind the firewall a
> service runs which needs to be visible to the world at large in this
> case let's start with an easy one http, on port 80. 
> 
> No problems so far :) 
> 
> Now behind the firewall are 2 separate servers, each running a web
> service and each running on port 80. 
> 
> 1) The question is, with only 1 real world address available to you,
> what suggestions do you guy's have as to the configuration required to
> make both web servers available on the Internet ? So that incoming port
> 80 request on the firewall public interface go to the correct server. 

There is no way for the fw to be able to make a proper decision as to
where to DNAT the packets to, only based on the syn packet it originally
receives. However, you can set up a "reverse proxy" on the fw itself
which fetches the pages off of the appropriate web server and passes
the result.

> 
> 2) The same as scenario 1) except you have 2 addresses available but
> only one external NIC. 

This one is easy.

> 
> 3) Same as 2) except you have 2 NIC's. 

As easy as the second one.

Ramin

> 
> The reason for this is the following is that, i wish to understand if
> there is a path to this result. I realise there are probably many way's
> to skin this cat, and i have tried a few of them, some of you may
> already be doing this, but in my experience there seem to be a lot of
> pitfall's and consequently the issues i have faced seem to suggest the
> following: 
> 
> Some think it's possible, Some don't, some wish it was possible, many
> just say this way, others suggest that way, many just give up. 
> 
> All in all i would like to take this to the logical conclusion of
> getting it working in multiple scenarios securely and effectively. 
> 
> yours a.r.b. 
> 
> 
> 

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