Routing Multiple Inbound IP Addresses -- How?

[Gregory Nowak]

Ok, I think I see what you're going for.

In the below examples, I assume that you have an external ip, 1.2.3.4,
which you want to route to 192.168.0.1, and a second external ip,
5.6.7.8, that you want to route to 192.168.0.2. I also assume that
your network device connected to the dsl modem is eth0.

iptables -t nat -A PREROUTING -i eth0 --source 1.2.3.4 -j DNAT
--to-destination 192.168.0.1

and

iptables -t nat -A PREROUTING -i eth0 --source 5.6.7.8 -j DNAT
--to-destination 192.168.0.2

Note 1:, I know I'm using incorrect number ranges for the external ip
addresses.

Note 2: This might have line wrapped, so be sure to check for that if
doing cut and paste.

Note 3: I obviously haven't tested this, but it should work in theory,
as far as I understand iptables syntax. If you get errors, let me or
the list know, and I'll try to resolve them. Hth.

Greg


On Tue, Nov 29, 2005 at 08:24:37AM -0500, Janina Sajka wrote:
> Hi, Sina:
> 
> Didn't remember the term multihoming. I'll check that out.
> 
> So, here's my situation. My ISP provides me multiple ip addresses, if I
> want them. I want to take advantage of that in a way I think is
> appropriate. It would be easy if I just used the external, routable ip
> addresses directly--one for each machine perhaps.
> 
> But, I want to keep my internal, nonroutable scheme intact. For one
> thing, I have more machines than routable addresses. For another thing,
> I'd like the freedom to use the routables by function, rather than
> specific machine, meaning that I might migrate internally from one
> machine to another at some point, without changing the externals.
> 
> So, how do I do that NAT? Let's say I have four IP addresses. They're
> discontinguous. Internally, I have seven or eight machines (depending on
> the day).
> 
> Here's what I know I can do. I can route traffic arriving on address A
> port 80 to machine A-Prime port 80, and route traffic arriving on
> address B port 80 to machine B-Prime.
> 
> But, can I route traffic arriving on address C, whatever port, to
> machine C-Prime? Without specifying all the particular ports one at a
> time? Or as some kind of gargantuan range like 1-32767?
> 


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