Configuring the VPN overlay between the HQ FortiGate and cloud FortiGate-VM

Configure the cloud FortiGate-VM

To create an address for the VPN gateway:

1. Go to Policy & Objects > Addresses and click Create New > Address.
2. Set Name to local_subnet_10_0_2_0.
3. Set IP/Netmask to 10.0.2.0/24.

   

4. Click OK.

To configure a custom IPsec VPN:

1. Go to VPN > IPsec Wizard.
2. Set Name to Core_Dialup.
3. Set Template type to Custom.

   

4. Click Next.
5. Configure Network settings:

   Remote Gateway	Dialup User
   Interface	port1
   NAT Traversal	Enable

6. Configure Authentication settings:

   Method	Pre-shared Key
   Pre-shared Key	Enter the pre-shared key.
   Version	1
   Mode	Aggressive This setting allows the peer ID to be specified.
   Accept Types	Specific peer ID
   Peer ID	IaaS The other end of the tunnel needs to have its local ID set to IaaS.

   

7. Leave the default Phase 1 Proposal settings and disable XAUTH.
8. Configure the Phase 2 Selector settings:

   Name	Ent_Core
   Local Address	Named Address - local_subnet_10_0_2_0
   Remote Address	Named Address - all This setting allows traffic originating from both the remote subnet 10.100.88.0 and the health checks from the VPN interface on the remote FortiGate. For increased security, each subnet can be specified individually.

9. Click OK.

To configure remote and local tunnel IP addresses:

1. Go to Network > Interfaces and edit the Core_Dialup interface under port1.
2. Set IP to 172.16.200.1.
3. Set Remote IP/Netmask to 172.16.200.2 255.255.255.0. This is where remote health check traffic will come from.
4. Enable Administrative access for HTTPS, PING, and SSH.

   

5. Click OK.

To configure a route to the remote subnet through the tunnel:

1. Go to Network > Static Routes and click Create New.
2. Set Destination to Subnet and enter the IP address and netmask: 10.100.88.0/255.255.255.0.
3. Set Interface to Core_Dialup.

   

4. Click OK.

To configure a firewall policy to allow traffic from the tunnel to port2:

1. Go to Policy & Objects > IPv4 Policy and click Create New.
2. Configure the following:

   Name	Core_Dialup-to-port2
   Incoming Interface	Core_Dialup
   Outgoing Interface	port2
   Source	all
   Destination	local_subnet_10_0_2_0
   Schedule	always
   Service	ALL
   Action	ACCEPT

   

3. Configure the remaining settings as required.
4. Click OK.

Configure the HQ FortiGate

To create an address for the VPN gateway:

1. Go to Policy & Objects > Addresses and click Create New > Address.
2. Set Name to remote_subnet_10_0_2_0.
3. Set IP/Netmask to 10.0.2.0/24.
4. Click OK.

To configure a custom IPsec VPN:

1. Go to VPN > IPsec Wizard.
2. Set Name to FGT_AWS_Tun.
3. Set Template type to Custom.
4. Click Next.
5. Configure Network settings:

   Remote Gateway	Static IP Address
   IP Address	100.21.29.17
   Interface	port5
   NAT Traversal	Enable

6. Configure Authentication settings:

   Method	Pre-shared Key
   Pre-shared Key	Enter the pre-shared key.
   Version	1
   Mode	Aggressive This setting allows the peer ID to be specified.
   Accept Types	Any peer ID

7. Leave the default Phase 1 Proposal settings, except set Local ID to IaaS.
8. Disable XAUTH.
9. Configure the Phase 2 Selector settings:

   Name	FGT_AWS_Tun
   Local Address	Named Address - all This setting allows traffic originating from both the local subnet 10.100.88.0 and the health checks from the VPN interface. For increased security, each subnet can be specified individually.
   Remote Address	Named Address - remote_subnet_10_0_2_0

10. Click OK.

To configure local and remote tunnel IP addresses:

1. Go to Network > Interfaces and edit the FGT_AWS_Tun interface under port5.
2. Set IP to 172.16.200.2.
3. Set Remote IP/Netmask to 172.16.200.1 255.255.255.0.
4. Enable Administrative access for HTTPS, PING, and SSH.
5. Click OK.

Routing is defined when creating the SD-WAN interface. The firewall policy is created after the SD-WAN interface is defined.