cisco ASA NAT Design question

[michalis1234]

Dear All,

I have a Nat design question. I would like enhance the communicaton that i have with a partner company.

The issue is that we use common ip addressing for several networks.

You can see in the attached diagram .

I have currently an ASA 8.2.5 which i recently upgraded to 9.1.5 in order to be able to configure twice nat. My issue is that some of my inside users must be able to communicate with networks 172.16.10.0 /24 & 172.16.11.0 /24 the networks are already utilized in my network as well.

Hence I created static nats (outside,inside) for the specific servers that must be accessed in the partner's network, the problem is that my partner needs the same source address from all of my inside users that connect to specific servers. For example anyone that wants to connect to the web-server 172.16.10.100 should come with source address 172.16.253.100,  anyone that wants to connect to the FTP-server 172.16.10.200 should come with source address 172.16.253.200 and so on.

I was thinking that i could achieve this with twice nat (translating both source and destination, but after some experimenting i realized that this cannot be achieved with a single twice nat statement.

Between my routers there is a point to point mpls line which is secured by an ipsec vpn tunnel.

Can you please give me some suggestions on how can i overcome this issue.

Many Thanks,

[Daniel Hood]

What was the issue with the double NAT statement?

What was the configuration (lines) you entered as the double NAT?

[michalis1234]

First of all i created 4 static nats:

object network obj-172.16.10.100

host 172.16.10.100

nat (outside,inside) static 172.16.9.100

object network obj-172.16.10.200

host 172.16.10.200

nat (outside,inside) static 172.16.9.200

object network obj-172.16.11.100

host 172.16.11.100

nat (outside,inside) static 172.16.8.100

object network obj-172.16.11.200

host 172.16.11.200

nat (outside,inside) static 172.16.8.200

With the above static nats i can achieve communication for the 4 servers in my partner's network, but

I cannot achieve source address translation, as it is required.

If I use the below dymanic nat i can achieve source translation:

object network obj-172.16.10.0

subnet 172.16.10.0 255.255.255.0

nat (inside,outside) dynamic 172.16.253.100

but I would like to combine these 2 NAT configuration in one.

Hence I tried the below:

nat (inside,outside) 1 source dynamic obj-172.16.10.0 172.16.253.100 destination static 172.16.9.100 172.16.10.100

But unfortunately it does not work!

Can you please advice.

[nkarthikeyan]

Hi Mic,

In case if you have the overlapping networks @ both ends, then you need to perform NAT @ both the ends..... if you do it in your end and if the client end is not NATing it, then it will not work...

eg:

site A:

192.168.1.0/24

nat to 192.168.11.0/24

Site B:

192.168.1.0/24

nat to 192.168.12.0/24

encryption domain should be with the NATed ip address.... once end NAT will not help in this case....

Regards

Karthik