Technical Tip: FortiOS Packet Sniffer displays each Packet twice on GUI/CLI

When using the packet sniffer on FortiGate, both ingress and egress packets may appear twice in the sniffer output.

diagnose sniffer packet port1 'host 208.91.112.55' 4 10000 l
interfaces=[port1]
filters=[host 208.91.112.55]
2025-03-07 12:09:18.029629 port1 -- 10.21.4.33 -> 208.91.112.55: icmp: echo request
2025-03-07 12:09:18.029629 port1 -- 10.21.4.33 -> 208.91.112.55: icmp: echo request
2025-03-07 12:09:18.035475 port1 -- 208.91.112.55 -> 10.21.4.33: icmp: echo reply
2025-03-07 12:09:18.035475 port1 -- 208.91.112.55 -> 10.21.4.33: icmp: echo reply

However, a packet sniffer on the upstream device does not show the packets being sent twice by FortiGate, and debug flow does not indicate that FortiOS is processing the received packet twice.

This issue has been resolved in FortiOS version 7.6.3.