IPSec VPN - How to Create a Net-to-Net Connection (Endian-2.5-to-Cisco ASA)

For the Cisco side we'll be using the graphical ASDM (version 6.1) administration tool. For convenience, we'll use the built-in VPN wizard found under Wizards > IPSec VPN Wizard.

The first step is to select the "Site-to-Site" VPN Tunnel type and we’ll use the default outside interface for our connection.

Click Next button to continue.

The next step is to configure the remote peer IP address (remote VPN endpoint) and provide the pre-shared key for the connection (configured earlier). The ‘Tunnel Group Name’ should be either the IP address or hostname of the remote VPN connection and should match on both endpoint devices of the VPN tunnel.

Click Next button to continue.

Next, we can configure the IKE policy where we’ll just use the defaults as those match up with our Endian default settings.

Click Next button to continue.

Now we can configure the IPSec Encryption and Authentication policy which (again) we’ll use the defaults to match up with our Endian.

Click Next button to continue.

Next, we’ll configure which networks are being protected on either side of the tunnel and apply a NAT exemption policy to any intra-VPN traffic. For the ‘Local Network’ we’ll select the 172.16.15.0/24 subnet which is aliased as our inside-network. For the remote network, we’ll use the Endian Green (LAN) IP range of 192.168.35.0/24. We’ll keep the VPN traffic exempt from NAT on the outside interface.

Click Next button to continue.

The very last step is a confirmation window with all of the relevant VPN information to confirm before finishing the VPN connection setup process.

Click Finish button to save your configuration

The last step with the Cisco firewall is to ensure we have an appropriate access policy (ACL) to allow traffic from the internal Cisco LAN to the Endian Green (LAN). We can do this by going to ‘Configuration > Firewall > Access Rules’ and adding a rule to the inside interface. In this example, we’re creating a rule to allow all traffic (service = ip) between the two protected networks.

On the Site A VPN device, you should the "Status" go from CLOSED to OPEN which indicates a successful connection. You should also similarly be able to see a successful VPN connection within the ASDM administrative console as well.

Now you should be able to successfully test all internal access to remote devices (resources) from both sides of the VPN tunnel. Anything from a simple ICMP ping to an RDP session or remote web server should be accessible across the tunnel.