VPN Tunnel, subnets conflict

ipsecnetworkingsubnetvpn

I'm trying to create IPsec VPN Tunnel between two sites.

Site 1
Fortigate 140D
Local subnet : 192.168.1.0/24

Site 2
Fortigate 100D
Local Subnet : 192.168.2.0/24

But when I try to create it, it gives me the error: Conflicts with existing local subnet(s)

I don't understand why… can anyone explain it to me? What I have to do?

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Best Answer

By default Fortigate firewall's dedicated management interface has an IP address from 192.168.1.0/24 range. Please note, it is not the internal interface, it's another dedicated port for management, with default ip 192.168.1.99. You can connect to the firewall directly with this interface using an ip address 192.168.1.2 and subnet 255.255.255.0.

I guess, this default setting of the firewall is the reason of the conflict. You can investigate this yourself and find it out. Either you will need to change the management ip range or the remote network ip range for the vpn to work.

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