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I'm dealing with a FortiGate 100D for the first time, and am scratching my head as there doesn't seem to be an easy way to mirror ports in the switch; which is really a facility that I presumed it would provide.

Ideally, I want to mirror one (or more) ports to another port, so that I can track the traffic that is flowing through it.


  • mirror WAN1 to an internal port
  • mirror an internal port to a different internal port
  • etc.

I could do it with a passive network tap, of course; but it seems really strange to me that the 100D doesn't seem to expose an easy way to do this.

I'm new to the hardware/FortiOS, though -- so possibly I am simply missing something obvious.

Many thanks if someone can point me in the direction of how to set this up on FortiOS/FortiGate.

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Aha, nevermind. I found it in the FortiOS CLI reference, under switch-interface > span/span-dest-port/span-direction/span-source-port. – Remi May 9 '13 at 2:54
Remi: I get alerted for the tags fortinet and fortigate, so I came here. I just wanted to mention that I'm working on an NMS using a project called flow-inspector and a robust flow capturing software by a company qosient called argus. Both are free. Check them out. – mbrownnyc May 9 '13 at 15:01

1 Answer 1

up vote 2 down vote accepted

From the FortiOS CLI reference, under system > switch-interface:

config system switch-interface
  edit <group_name>
    set member <iflist>
    set span {enable | disable}
    set span-dest-port <portnum>
    set span-direction {rx | tx | both}
    set span-source-port <portlist>
    set type {hub | switch | hardware-switch}
    set vdom <vdom_name>
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