cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
510
Views
5
Helpful
4
Replies

NAT Question

jim_berlow
Level 3
Level 3

I have a general NAT question I hope you can help us with. We are converting from a large public ip address block (no NAT whatsoever) into a private address space using a combination of NAT / PAT, etc.

I think the ASA can do this without issue (version 8.04), but want to verify. On the Outside interface I have a completely different subnet than the public space I have inside. (Basically a /30 on the outside to the provider and a large /19 on the inside). Now, can I NAT this /19 to the Outside interface even though is is on a different subnet than the /30 assigned to the Outside?

Example (ip's changed to preserve the innocent):

Outside IP = 23.2.2.2 /30 (apologies to whoever owns this space)

Inside IP = 167.2.0.0 /19 (more apologies)

Can I NAT that 167.2.0.0 /19 to the Outside without issue?

Thanks for your assistance!

Jim

4 Replies 4

Jon Marshall
Hall of Fame
Hall of Fame

Jim

Yes no problem. I'm assuming you mean hide all the 167.2.0.0/19 addresses behind 23.2.2.2 ?

If so

nat (inside) 1 167.2.0.0 255.255.224.0

global (outside) 1 interface

If i have misunderstood let me know.

Jon

Thanks, Jon - that is part of it.

How about if we have public servers on an IP address example 167.2.1.1 (SMTP)? Can I simply create a statement like this and will this work? This host is currently assigned the public IP 167.2.1.1 right on its tcp/ip stack and it will now be assigned a private address like 10.1.226.223 (assume I have done all the routing inside correctly, etc).

static (Inside,Outside) tcp 167.2.1.1 25 10.1.226.223 25 netmask 255.255.255.255

Thanks for your help,

Jim

Jim

As long as any requests for 167.2.1.1 are routed to the outside interface of your ASA from the Internet then yes you should be fine.

Jon

Thanks, Jon. That is exactly what I wanted to verify.

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: