Hfc mac address sniffer update#

When troubleshooting networks, it helps to look inside the header of the packets. The following sniffer CLI command includes the ARP protocol in the filter which may be useful to troubleshoot a failure in the ARP resolution (for instance PC2 may be down and not responding to the FortiGate ARP requests).ДЇGT# diagnose sniffer packet any вЂњhost or host or arpвЂќ 4 Remember to stop the sniffer, type CTRL+C.ДЇGT# diagnose sniffer packet any вЂњhost or host вЂќ 4ДЇGT# diagnose sniffer packet any вЂњ(host or host ) and icmpвЂќ 4 With verbosity 4 and above, the sniffer trace will display the interface names where traffic enters or leaves the FortiGate unit. In the output below, port 443 indicates these are HTTPS packets, and 172.20.120.17 is both sending and receiving traffic. At this verbosity level you can see the source IP and port, the destination IP and port, action (such as ack), and sequence numbers.

This will display the next three packets on the port1 interface using no filtering, and using verbose level 1. ДЇor a simple sniffing example, enter the CLI command diag sniffer packet port1 none 1 3. If you do not put a number here, the sniffer will run forever unit you stop it with. The number of packets the sniffer reads before stopping. The filter must be inside single quotes (вЂ).Дў вЂ“ print header and data from IP of packetsДЈ вЂ“ print header and data from Ethernet of packetsД¤ вЂ“ print header of packets with interface name вЂњnoneвЂќ indicates no fil- tering, and all packets will be displayed as the other arguments indicate. What to look for in the information the sniffer reads. This can also be вЂњanyвЂќ to sniff all interfaces. The name of the interface to sniff, such as вЂњport1вЂќ or вЂњinternalвЂќ. The general form of the internal FortiOS packet sniffer command is:

Hfc mac address sniffer update#

This is due to the ARP update that is sent out when the VIP address is configured. You will notice this when you are sniffing packets because all the traffic will be using the virtual IP addresses. If you configure virtual IP addresses on your FortiGate unit, it will use those addresses in preference to the physical IP addresses. Note that RPF can be disabled by turning on asymmetric routing in the CLI (config system setting, set asymetric enable), however this will disable stateful inspection on the FortiGate unit and cause many features to be turned off. Sniffing packets can also tell you if the FortiGate unit is silently dropping packets for reasons such as Reverse Path Forwarding (RPF), also called Anti Spoofing, which prevents an IP packet from being forwarded if its Source IP does not either belong to a locally attached subnet (local interface), or be part of the routing between the FortiGate unit and another source (static route, RIP, OSPF, BGP). If you are running a constant traffic application such as ping, packet sniffing can tell you if the traffic is reaching the destination, what the port of entry is on the FortiGate unit, if the ARP resolution is correct, and if the traffic is being sent back to the source as expected. Before performing a trace on any NP2/NP4 interfaces, you should disable offloading on those interfaces.

If your FortiGate unit has NP2/NP4 interfaces that are offloading traffic, this will change the sniffer trace. Packet sniffing can also be called a network tap, packet capture, or logic analyzing. When troubleshooting networks and routing in particular, it helps to look inside the headers of packets to determine if they are traveling along the expected route. H o w to perform a sniffer trace (CLI and Packet Capture)