Configuring a site-to-site VPN using a Cisco ASA

In this section, we are going to take a look at configuring a site-to-site VPN tunnel using the Adaptive Security Appliance (ASA). Using the following topology, we will apply some fundamental configurations on both ASAs before configuring the VPN tunnel. We want to ensure the devices have basic connectivity between each other:

On ASA-1, the following configurations were applied:

• GigabitEthernet1—200.1.1.2/30 (Outside).
• GigabitEthernet0—192.168.2.1/24 (Inside).
• PAT set to use the IP address on the Outside interface.
• Set a default route to the ISP. In the lab configuration, the default gateway for ASA-1 is 200.1.1.1/30.

On ASA-2, the following configurations were applied:

• GigabitEthernet1—100.1.1.2/30 (Outside)
• GigabitEthernet0—192.168.4.1/24 (Inside)
• PAT set to use the IP address on the Outside interface
• The default gateway for ASA-2 is 100.1.1.1/30

Checking the device connectivity from ASA-1, we ping 100.1.1.2:

Since we've ensured connectivity between...