Technical Tip: IPsec VPN FortiGate dial-up client requires defining phase 2 selector sources
Description
This article describes how, when a FortiGate is behind an ISP that provides a dynamic IP address via DHCP or PPPoE, it is necessary to use an IPsec VPN dial-up client configuration on that device.
When using a route-based IPsec VPN configuration, Phase 2 or quick-mode selectors must be defined with internal/protected subnets to allow the IPsec VPN dial-up server configuration on the peer FortiGate device to dynamically install routes on its end.
When using a route-based IPsec VPN configuration, Phase 2 or quick-mode selectors must be defined with internal/protected subnets to allow the IPsec VPN dial-up server configuration on the peer FortiGate device to dynamically install routes on its end.
Scope
FortiGate.
Solution
When configuring a route-based IPsec VPN dial-up client configuration, it is necessary to define the internal/protected subnets as sources via a Phase 2 selector. It may be necessary to select the Convert to Custom Tunnel button to see the Phase 2 Selector's view.
For example, if the internal/protected subnet from which traffic is sourced is 192.168.1.0/24, the following Phase 2 selector needs to be defined:
For example, if the internal/protected subnet from which traffic is sourced is 192.168.1.0/24, the following Phase 2 selector needs to be defined:
Local Address:
Type: Subnet
Value: 192.168.1.0/255.255.255.0
Remote Address:
Type: Subnet
Value: 0.0.0.0/0.0.0.0 (or specific subnet on the peer's protected network)
Type: Subnet
Value: 192.168.1.0/255.255.255.0
Remote Address:
Type: Subnet
Value: 0.0.0.0/0.0.0.0 (or specific subnet on the peer's protected network)
Note: In dial-up IPsec VPN configurations, it is not possible to configure multiple Phase 2 selectors. Only a single 0.0.0.0/0 <-> 0.0.0.0/0 Phase 2 entry is supported to allow flexibility for dynamic peers. Traffic to specific subnets must be controlled using firewall policies and routing.