How could configure the ASA-5515X for Public IP


Could anyone give me a sample configuration for the below scenario.

ISP gives a point to point IP and a Public IP range. How could configure the ASA-5515X (8.6) for given multiple Public IP.

Point to Point IP : –
Public IP range for Internal Server: –  

Public IP will be used directly on internal Server and not use for masking Private IP. Also don’t want to configure VLAN in ASA.

Thanks in advance.
Musabr59 IbnrAsked:
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Musabr59 IbnrAuthor Commented:
Hi Muhammad Burhan,

Thanks for response.

But I need to know how to configure ASA for multiple Public IP which will be directly used on internal server behind the ASA not VPN configuration.
Pete LongTechnical ConsultantCommented:
Hi your post is confusing? do you have two public ranges you want to use?

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ArchiTech89IT Security EngineerCommented:
So if I understand correctly...

1. You want PPP on the 'outside' interface going to an ISP to use one of the 2 IP addresses you've mentioned--either or, presumably with the upstream router at

2. You want to use an address from the block of IPs you've been given of to on the 'inside' interface to connect to your server, probably using as the default route for the server.

Did I get that right? If so, I'm not sure what's going on here.

With number 1, it's a little odd because it would likely need a /29, leaving 6 usable host addresses. But you only list 2 (3, if you include the assumed next hop router).

And with number 2, this is again tipping towards odd to me--to have that many hosts, you'd have to have a /27, which would normally allow for 30 hosts, not 19.

Furthermore, if you do that, you'd have to put every other device on the inside on the same public address space assigned to the segment. And that might not be doable.

You'd normally handle the server issue with NAT. You'd give the server a non-routable (RFC 1918) IP address inside the firewall, and then on the firewall itself, NAT the inside 'private' IP address to the outside 'public' one. That means that the server thinks of itself as a address for example, but when the world wants to contact it, they would send traffic to like that. I know you said that's not what you want, but it is common practice.

Maybe you could clarify your needs a bit?
Musabr59 IbnrAuthor Commented:
Thanks for your time.

Sorry for security purpose I don’t want to mention actual Public IP.

Let me explain  –

ISP gives a point to point IP: [ -] for outside interface. I’ll use for my ASA outside interface.

ISP also gives me Public IP block like-  [ -]

I know its common practice to masking private IP through Public IP but I need to use Public IP directly on my internal server. Network scenario :


I need to know, how to configure this Public IP [] block in ASA for internal server.
ArchiTech89IT Security EngineerCommented:
Well, you can probably just use identity NAT. Something like this (post ASA version 8.3)...

First, create a network object:
    object network PUB-

Then just NAT it to itself:
    nat (inside,outside) source static PUB- PUB-

I think that should do what you're describing.

P.S. You'd do that for each server/device you want to use a public IP with.

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Musabr59 IbnrAuthor Commented:
If I use range for network object -

object network PUB-IP-Block

nat (inside,outside) source static PUB-IP-Block PUB-IP-Block

Would it work ?
ArchiTech89IT Security EngineerCommented:
It might. But I don't know if syntax for the actual NAT command might be different when dealing with a subnet. You'd have to check. Either that or give it a try. ;-)

Here's the 8.4/8.6 configuration guide link for NAT:

Good luck!
Musabr59 IbnrAuthor Commented:
Hi Noel,

I’m planning to implement this in ASA.

Thanks again for your help.
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