install mikrotik as bridge

RouterOS General
1

Dear Experts,
i have fortigate firewall connected to internet modem with public ip address
i want to install mikrotik as bridge in between so i can get all logs and connections

i installed the bridge port1 to modem and port2 to fortigate
and everything worked good and i see the connections passing through the mikrotik and i can monitor them

my problem is that all the connection has source ip is the real ip that is set on fortigate
while i need to know the source ip inside the LAN

i tried to stop NAT on fortigate rule then i saw the source ip’s but the internet stopped on LAN machines
is there any work around for that problem or any suggestion i can take it into consideration

thank you in advance

2

Put the Mikrotik bridge on the other side of the Fortigate.
Fortigate → Mikrotik (Port 2), then Mikrotik (Port 3) → Switch

Disable DHCP Server
Edit port 3 interface, set master-interface to none
Create bridge1
Add port 2 and port 3 to the bridge.
Go to Bridge, click the settings button
Enable “Use IP Firewall”

The reason port 2 and 3 need to be in the same bridge as opposed to leaving port 3 as slave to port 2 is because firewall rules don’t apply to interfaces that are master/slave
By enabling “Use IP Firewall”, you can use IP > Firewall to create rules. It has more features than Bridge > Filter rules.

3

So what you are saying is to remove mikrotik from between modem-fortigate and put it in between fortigate-switch right ?

If this is the case my question is there is any chance to do it as my first scenario?

Thank you in advance

4

Yes - in my scenario you’d be moving the Mikrotik from in front of the fortigate to behind the fortigate.

If you want to have it in front of the fortigate (Fortigate → Mikrotik → Modem) Then look for an option in the fortigate called operation mode. Change it from Gateway/NAT to Router/Transparent.

Then the private IPs shall pass through to the Mikrotik.

On the fortigate your wan port should be set to DHCP. You would need a route on the fortigate to send 0.0.0.0/0 to the Mikrotik’s ether2 IP (by default: 192.168.88.1)


Or… if the fortigate has the function to act as a plain old switch and the functions you need still work, then this would be an easier route.

5

I will study the case of putting mikrotik before fortigate but i have issue that i have 2 fortigate ha and 2 switches stackable for redundancy so in this case i need 2 mikrotik to keep redundancy

Thank you in advance