FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
This article describes how to handle a scenario where the IPsec Tunnel is up and traffic seems to be leaving FortiGate but is not reaching the remote end.
This article applies to all the possible scenarios mentioned below:
FortiGate=====IPSec Tunnel=====FortiGate
FortiGateVM======IPSec Tunnel====FortiGate
FortiGate=====IPSec Tunnel======Third Party
Scope
FortiGate.
Solution
Follow these steps:
Verify the IPSec ports being used on FortiGate using the following commands.
diagnose vpn ike gateway list name <tunnel_name>
diagnose vpn tunnel list name <tunnel_name>
If port 500 is being used, try to switch the connectivity to port 4500.
config vpn ipsec phase1-interface
edit "VPN-Phase1"
set nattraversal forced
end
Make sure NAT-Traversal is also enabled on the remote end on a Third-party device.
Flush the tunnel.
diagnose vpn tunnel flush <tunnel_name>
diagnose vpn ike gateway flush name <tunnel_name>
Verify if the connectivity is established on port 4500 using the same commands in the first step.
Initiate the traffic and it could work after this.
