NATing Question

D.Callahan — Wed, 29 Oct 2025 15:29:12 GMT

I am using two PA-440 firewalls for a laptop testing. The purpose of the Lab is to test for VPN connectivity before deployment.

Firewall A = has an external IP of 17.11.19.69/30 - Internal address 2.2.2.2/24 (LAN)

Firewall B = has an external IP of 17.11.19.68/30 - internal address 3.3.3.3/24 (LAN)

Because I have a block of public IP's, each firewall connects to the same Modem router.

To avoid having traffic redirect issue, how do i setup NAT to get the firewalls to establish a ipsec vpn tunnel.

Thank you.

Re: NATing Question

Elwin3 — Wed, 29 Oct 2025 17:43:49 GMT

Hey D.Callahan,

Since both firewalls are connected to the same modem and using public IPs from the same range, you don’t need to use NAT for the VPN traffic. NAT would actually prevent the tunnel from forming, because each peer needs to see the other’s real public IP. Just make sure each firewall uses the other’s public IP as the VPN peer, and add a rule to exclude the LAN-to-LAN traffic from NAT (for example, 2.2.2.0/24 to 3.3.3.0/24).

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NATing Question

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