A service for WAN on a server behind 2 fortigates with IPSec VPN between them

Question

Hello der Fortinet Community,

I am new to Fortigates and I have the case depicted on the attached picture: A server in LAN 2 (Interface L2) behind the Fortigate 2 (FortiWiFi 60CX-ADSL-A, Firmware v5.2.15,build766 (GA)) which is beign addressed from WAN (Interface W) through the Fortigate 1 (FortiWiFi 60CX-ADSL-A, Firmware v5.2.15,build766 (GA)) and IPSec VPN (Interfaces V1, V2, which are the VPN interfaces). The server runs a number of services that should be accessible from WAN. Lets take FTP as one example.

I have the following relevant policies of the Fortigate 1.

F1.I. WAN - V1: Source: all; Destination: Server (Virtual IP); Schedule: always; Service: FTP; Action: accept; NAT: enable. F1.II: V1 - WAN: Source: all; Destination: all; Schedule: always; Service: all; Action: accept; NAT: enable.

The Virtual IP object "Server" has the following configuration:

Interface: W1, Type: static NAT, Source Address Filter: disabled, External IP Address/Range: 0.0.0.0 - 0.0.0.0 Internal IP Address/Range: xxx.yyy.zzz.nnn - xxx.yyy.zzz.nnn (the IP Address of the Server in LAN 2) Port Forwarding: enabled, Protocol: TCP, External Service Port: 21 - 21 Internal Service Port: 21 - 21

Besides that, I have the following relevant policies on the Fortigate 2.

F2.I V2 - L2: Source: all; Destinastion: Server (Address); Schedule: always; Service: FTP, Action: accept; NAT: disable. F2.II L2 - V2: Nothing... but should I have an accepting policy for Server -> all?

The Address object "Server" has the following configuration:

Type: IP/Netmask, Subnet / IP Range: xxx.yyy.zzz.nnn (the IP Address of the Server in LAN 2), Interface: any, Show in Address List: yes.

When I try to connect via FTP from WAN using the address of the WAN-Interface, I see the number of packets increasing on F1.I, but nowhere else and, obviously, I cant establish a connection. Could you please help me with what and how I should change to allow the required connectivity?

rreimche · Answer

I suppose, the settings of the VPN Tunnel may be also relevant, so here are they.

At Fortigate 1:

Network

IP Version: IPv4

Remote Gateway: Dynamic DNS

Dynamic DNS: ourdomain.dyndns.org

Interface: W

Mode Config: disabled

NAT Traversal: enabled

Keepalive Frequency: 10

Dead Peer Detection: enabled

Authentification

Method: Pre-Shared Key

Pre-shared Key: secret

IKE Version: 1

IKE Mode: Main (ID Protection)

Phase 1 Proposal

Algorithms: AES128-SHA256

Diffie-Hellman Groups: 14, 5

XAUTH

Type: Disabled

Phase 2 Selectors

Name: V1

Local Address: Subnet 0.0.0.0/0.0.0.0

Remote Address: Subnet 0.0.0.0/0.0.0.0

(here we have several pairs of Encryption and Authentication types, I omit them)

Enable Replay Detection: enabled

Enable Perfect Forward Secrecy (PFS): enabled

Diffie-Hellman Groups: 14, 5

Local Port: All

Remote Port: All

Protokoll: All

Autokey Keep Alive: disabled

Auto-negotiate: enabled

Key lifetime: 43200 seconds

Fortigate 2: everything is identical except:

Remote Gateway: Static IP Address.

IP Address: our static IP address of W

Interface: the local WAN-Interface of the Site where Fortinet 2 functions

Auto-negotiate: disabled.

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