Virtual Private Network (VPN) is a network connection that establishes a secure tunnel between remote peers using public ip address to connect 2 or more private networks. Encryption is use to ensure privacy and integrity of the Data.

IPsec-based VPN technologies use the Internet Security Association and Key Management Protocol (ISAKMP, or IKE) and IPsec tunneling standards to build and manage tunnels. ISAKMP and IPsec accomplish the following:

  • Negotiate tunnel parameters.
  • Establish tunnels.
  • Authenticate users and data.
  • Manage security keys.
  • Encrypt and decrypt data.
  • Manage data transfer across the tunnel.
  • Manage data transfer inbound and outbound as a tunnel endpoint or router.

In this tutorial I will show you how to configure site to site VPN between 2 FTDv 7.3.0.

Below is how the setup looks like.

Before we start with the configuration of the site to site VPN let’s create a few objects that we will be using in the setup. Do this for both the FTDv in Active an

  1. Site 1 Network: 10.16.2.0/24
  2. Site 2 Network: 172.16.2.0/24

Go to Objects > Networks and click on Add + button.

Add Site 1 Network Object

Add Site 2 Network Object

Now let’s begin configuring the Site to Site VPN between 2 sites.

Step 1 – Create a site to site policy on FTDv7-3-0-Active

Go to Device

  1. Connection Profile Name: ActivetoS2SDemo
  2. Type: Policy Based
  3. Local VPN Access Interfaces: outside (GigabitEthernet0/0)
  4. Local Network: Site2 (The inside network of the Local Network)
  5. Remote Site: Static
  6. Remote IP Address: <Public IP Address of the VPN Termination>
  7. Remote Network: Site1 (The inside network of the remote network)

Step 2 – Configure the NAT Rule on FTDv7-3-0-Active

If you did not enable the NAT Exempt feature in the SITE-TO-SITE CONNECTION settings you can manually create a NAT Rule.

Step 4 – Configure the Access Control Policy on FTDv7-3-0-Active

Allow Site1 (Remote Local Network) traffic from outside (VPN) to inside Site2 (Local Network).

Step 5 – Create a site to site policy on FTDv7-3-0-S2SDemo

  1. Connection Profile Name: ActivetoS2SDemo
  2. Type: Policy Based
  3. Local VPN Access Interfaces: outside (GigabitEthernet0/0)
  4. Local Network: Site2 (The inside network of the Local Network)
  5. Remote Site: Static
  6. Remote IP Address: <Public IP Address of the VPN Termination>
  7. Remote Network: Site1 (The inside network of the remote network)

Step 6 – Configure the NAT Rule on FTDv7-3-0-S2SDemo

If you did not enable the NAT Exempt feature in the SITE-TO-SITE CONNECTION settings you can manually create a NAT Rule.

Step 7 – Configure the Access Control Policy on FTDv7-3-0-S2SDemo

Allow Site2 (Remote Local Network) traffic from outside (VPN) to inside Site1 (Local Network).

Above are the basic steps to configure the site to site VPN between 2 FTDv.

The official FDM 7.3 Configuration guide can be found here.

https://www.cisco.com/c/en/us/td/docs/security/firepower/730/fdm/fptd-fdm-config-guide-730/fptd-fdm-s2svpn.html