Networking question on cisco pix 515e

vayusa1234 · ‎06-19-2006

Hi everyone,

First I wanted to say thanks for the help people gave to me earlier. And I wanted to post a second question to see if this could be done. Our firewalls are in a hosting facility and we have been allocated a chopped up subnet.

NOTE: IP's have been changed to protect their identity

We have been given four subnets:

10.1.10.16/29 <-Currently the external inferface is mapped to these

10.2.10.24/29 <- One interface is assigned this subnet, I know not great but this is how I have inherited it

10.2.10.32/29 <- Second interface is assigned this subnet

and we just got 10.2.10.128/25 <-currently unassigned.

It is obvious that IP space is tight right now for us. And we have a UR with 6 ports, so I could assign that /25 segment to another IP. But ideally i would like to somehow virtualize these segments, atleast the /25 so it is not assigned to any particular interface. So i then could put in traditional non routable address space on the other interfaces and then do nats as I wish. So is this possible. Ideally i would like to redo Inside and DMZ with private address space and then have the the last three subnets have the ability to nat to any internal zone i want.

Thanks for looking, and I appreciate everyone's input.

vayusa1234 · ‎06-20-2006

on a good point we have one router in place rather then two different ones. I have tried to create a nat but I am not getting any luck as of yet on it.

grant.maynard · ‎06-21-2006

use private IP addresses on your internal and DMZ interfaces, use public IPs on outside. Use NAT to hide private IPs behind public IPs.

If you are a hosting company then you may want to conside security contexts in PIX v7 - that gives you virtual firewalls (two by default, more by licence) which can have different IPs for each context on the same physical interface.

vayusa1234 · ‎06-21-2006

So if i move the segments to private IP space, i should be able to create NAT's to whatever internal IP i need on any of the three subnets (as long as the router dumps it to the firewall) as long as the nat is there?

grant.maynard · ‎06-21-2006

yes, normally you would use "nat" and "global" statements to NAT outgoing traffic, with "static" statements for any servers which need to be reachable from the internet.

You can choose whether or not you NAT between internal interfaces.