One-to-One NAT - DMZ to inside - how do I make it work?

[darren_g]

Folks.

I'm apparently having a particularly stupid day, because I can;t make something as simple as one-to-one NAT work.

Scenario is this.

I have an IP in my DMZ. I have assigned this IP to a particular server which is hosted on my INSIDE (secure) network.

All I want to do is take this IP address and NAT it to the inside address. Something like this

IP addresses have been changed to protect the stupid (me!).

So - request comes in from the web to 1.2.3.91, and I want to redirect it to 10.100.1.120 - only needs web browsing and PING.

but I can not, for the life of me, get it right.

I've got the following NAT rule

Original packet

Source Zone - Outside

Destination Zone - DMZ

Source Address - Any

Destination Address - 1.2.3.91

Translated Packet

Source Translation : None

Destination translation : 10.100.1.120

The security policy is as follows

Source : Outside

Source Address : Any

Destination : Inside

Destination Address : 10.100.1.120

I'm happy for anyone to point out where I'm being stupid and laugh at me - I know it's something obvious, but I'm banging my head trying to sort out what.

thanks

[Ameya-Kawimandan]

Can you try to add a static route for 1.2.3.91/32 reachable through DMZ interface.

Make sure the packets are being received on the firewall using traffic logs.

P.S: Without addition of this  static-route ,NAT rule Outside to Outside should be able to translate these packets.

Try refreshing arp table of the upstream router.

>test arp gratuitous ip 1.2.3.91 interface <outside interface>

[darren_g]

Nadir wrote:

Can you try to add a static route for 1.2.3.91/32 reachable through DMZ interface.
Make sure the packets are being received on the firewall using traffic logs.

Not sure what you mean - add a static route for 1.2.3.91/32 *where*?

I can see *one* packet (session) which made it through, at some point in the past (I've tweaked the config file so many times since then trying different options I've lost track). I've gone back through the config logs and returned the config to exactly what it was back then - once it commits, I'll try again.

Nadir wrote:

P.S: Without addition of this  static-route ,NAT rule Outside to Outside should be able to translate these packets.
Try refreshing arp table of the upstream router.
>test arp gratuitous ip 1.2.3.91 interface <outside interface>

The gratuitous arp fails, vis-a-vis

Server error : cannot send gratuitous ARP

Rolling the config back did me no good at all. I'm at an absolute loss here. I *must* be doing something stupid, I just can't figure out what!

[Ameya-Kawimandan]

Please Allow the Original address  1.2.3.91  in the Security rule.

Source : Outside

Source Address : Any

Destination : Inside

Destination Address : 10.100.1.120

Change to :

Source : Outside

Source Address : Any

Destination : Inside

Destination Address : 1.2.3.91

[HULK]

Hello Darren,

Could you please provide a snapshot of traffic log for this destination ( internal server IP 10.100.1.120).

Example:

Thanks

[darren_g]

akawimandan wrote:

Please Allow the Original address  1.2.3.91  in the Security rule.

Source : Outside
Source Address : Any
Destination : Inside
Destination Address : 10.100.1.120

Change to :

Source : Outside
Source Address : Any
Destination : Inside
Destination Address : 1.2.3.91 

Done that. I put *both* the inside (RFC1918) address and the outside (real) address in the allowed destinations and it still didn't work. I've now put just the outside address, and still no good.