FortiGate
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.
kumarh
Staff
Staff
Article Id 353469
Description

This article describes how to resolve a common error encountered while configuring an IPsec dial-up tunnel on FortiGate when mode-cfg is enabled.

 

image (12).png

 

Scope All FortiGate firmware version.
Solution

When mode-cfg is enabled, FortiGate acts as a DHCP server for VPN clients, dynamically assigning IP addresses and other network configuration details. To avoid the error, it is essential to configure the ipv4-start-ip and ipv4-end-ip range (or the equivalent IPv6 range, if applicable).


For instance,

 

config vpn ipsec phase1-interface

edit <vpn tunnel>

set ipv4-start-ip X.X.X.X <- Where (X.X.X.X and Y.Y.Y.Y is starting and ending IP range).
set ipv4-end-ip Y.Y.Y.Y

end

 

After setting the IP range, the error should no longer appear.