Multiple public IPs statically NAT'd to a single inside host

I have a PIX (Version 6.3) 515E configured with an inside and outside interfaces. I want to transition the existing T1 connection to a new T1 connection. In doing so, I'd like to have the existing static NAT definitions to work across both connections until the DNS is transferred over and then the original T1 connection is de-commissioned. So say I had:

outside: 11.11.11.128/25 outside2: 22.22.22.96/27 inside: 10.0.0.0/24

Essentially what I would like to do is:

global (outside) 10 interface global (outside2) 20 interface

nat (inside) 10 0.0.0.0 0.0.0.0 0 0

static (inside,outside) 11.11.11.130 10.0.0.10 netmask 255.255.255.255 static (inside,outside2) 22.22.22.110 10.0.0.10 netmask 255.255.255.255

The PIX translates connections into 11.11.11.130 properly. It receives ping requests on 22.22.22.110, but no responses. I believe this is because of the default NAT route is back through outside. I could of course change the default NAT route to outside2, but then it should break the existing static NATs. How do I go about implementing this as I believe it is possible?

Reply to
Lone
Loading thread data ...

That's fine provided that there is an unambiguous way to determine which traffic should head to outside and which should head to outside2. As long as the range of source IPs that can read one of the two interfaces is fixed, you can use static "ip route" statements. The step above that would to allow dynamic routing configuration via OSPF, but unless you already have OSPF set up, that's probably not the best way to proceed.

What you cannot do is have two default routes and expect that because a packet came in via one interface, that the PIX will "somehow" remember the interface and reply back through that interface. The PIX cannot do that. The PIX figures out which interface to go to via the routing tables -- packet by packet.

There is no such thing as a "NAT route". If you are thinking of

global (outside) 10 interface global (outside2) 20 interface nat (inside) 10 0.0.0.0 0.0.0.0

then you need to know that the "0.0.0.0 0.0.0.0" of the nat statement is NOT a route: it is a source IP selector on outgoing traffic. For example, you could have

nat (inside) 10 10.0.0.5 255.255.255.255 nat (inside) 20 10.0.0.16 255.255.255.240 nat (inside) 30 0.0.0.0 0.0.0.0

and that would mean to apply global policy 10 to packets sourced from host 10.0.0.5, global policy 20 for packets sourced from 10.0.0.16-.31 and global policy 30 for all other inside source packets. But those aren't routes: they do not control which interface the traffic heads towards. Routes are handled via "ip route" or rip or ospf. Having different policies for the same inside interface allows you to select which IP address different hosts will present themselves as when going out through the -same- interface.

If arbitrary packets might enter through either interface, then you cannot do what you want through anything like the technique you are working with.... but under some conditions, you can do it via "reverse nat". I've written the constraints and configuration instructions in a few earlier postings in this newsgroup.

Reply to
Walter Roberson

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.