Can you use "custom NAT" with ISP redundancy?

[hotice_]

Hi,

By Custom NAT I mean use another routable IP besides the gateway for outgoing connections?

Is there a way to manually define this in a script?

[mcnallym]

Eash ISP connection in the ISP Redundancy is defined with what the next hop is after leaving the interface. You cannot have more then one gateway defined per ISP connection.

You can still configure a manual static route however if you need to force traffic out of a specific interface and down a different gateway, just that it will not be shared across the two External connections.

For instance are you looking at another connection that links to a business partner, you would just use static route going out via another interface to a router.

Is this what you are asking?

[hotice_]

No, sorry I think I wasn't clear,

Lets say I have ISP A and ISP B each with a defined subnet,

Firewall has two external IPs:
ISP A: 1.2.3.4
ISP B: 5.6.7.8

We are currently using an IP different from the gateway's IP for NATing, i.e.
all external traffic goes out as 1.2.3.5 instead of 1.2.3.4

How do I configure it so that it does the same thing for ISP B if its doable....

Hope its clearer this time

[mcnallym]

No Problem at all. I have been away which is why the delay in responding.

Is covered in #sk25152

Whilst this refers to Static NAT then it will also work for Hide NAT as well. You will need to have the firewall box proxy arp for the IP address as Auto Arp doesn't work correctly in ISP redundancy.

In general you define two Public Objects to hide behind and write the NAT rules so that uses the two Dynamic objects that you defined and configured on the actual gateways.

ie

src= internal_net dst= Dyn_ISP_A xlatesrc=Hide(Public IP Address) xlate dest = original

with

src= internal_net dst= Dyn_ISP_B xlatesrc=Hide(Public IP Address) xlate dest = original

for if goes out via ISP_B

You obviously don't need to configure an inbound rule as you would with a Static NAT.