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Fortinet

FortiGate Traffic Troubleshooting

Build a repeatable FortiGate troubleshooting workflow from basic reachability and routing through packet capture, flow debugging and IPsec validation.

intermediate6 steps≈ 55 min
01reference02reference03reference04reference05reference06troubleshooting
Recommended sequence

From first signal to next step

The order is editorial, not automatic. You can jump directly to a step when you already understand the previous ones.

  1. 01
    referenceFortinetbeginner

    Confirm local Layer 2 reachability

    FortiGate get system arp

    Start by checking whether expected local IP-to-MAC resolution exists on the correct interface.

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  2. 02
    referenceFortinetbeginner

    Test controlled IP reachability

    FortiGate execute ping and ping-options

    Use a controlled source/interface before moving into packet-level diagnostics.

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  3. 03
    referenceFortinetintermediate

    Validate the forwarding decision

    FortiGate get router info routing-table all

    Confirm the FortiGate has the expected connected, static or dynamic route.

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  4. 04
    referenceFortinetintermediate

    Observe the packets

    FortiGate diagnose sniffer packet

    Verify where traffic enters and whether it leaves the expected interface.

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  5. 05
    referenceFortinetadvanced

    Trace FortiOS processing

    FortiGate diagnose debug flow

    Inspect route lookup, policy matching, NAT and accept/deny decisions.

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  6. 06
    troubleshootingFortinetadvanced

    Apply the workflow to IPsec

    FortiGate IPsec tunnel is up but traffic does not pass

    Use the complete diagnostic chain when an established tunnel is not carrying expected traffic.

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