This blog post is a list of common troubleshooting commands I am using on the FortiGate CLI. It is not complete nor very detailled, but provides the basic commands for troubleshooting network related issues that are not resolvable via the GUI. I am not focused on too many memory, process, kernel, etc. details. These must only be used if there are really specific problems. I am more focused on the general troubleshooting stuff.
Coming from Cisco, everything is “show”. With Fortinet, you have the choice between “show | get | diagnose | execute“. Not that easy to remember. Likewise the “sys | system” keyword. It is always “diagnose sys” but “execute system”. 
Entering the correct vdom/gobal Config
Remember to enter the correct vdom or global configuration tree before configuring anything:
config global config vdom edit <vdom-name>
To show the running configuration (such as “show run”), simply type in:
show
To show the entire running configuration with default values, use:
show full-configuration
General Information
The very basics:
get system interface physical #overview of hardware interfaces get hardware nic <nic-name> #details of a single network interface, same as: diagnose hardware deviceinfo nic <nic-name> get system status #==show version get system performance status #CPU and network usage diagnose sys top #top with all forked processed diagnose sys top-summary #top easier, incl. CPU and mem bars. Forks are displayed by [x13] or whatever execute dhcp lease-list diagnose ip arp list diagnose ipv6 address list diagnose ipv6 neighbor-cache list diagnose sys ntp status diagnose autoupdate versions #lists the attack definition versions, last update, etc. diagnose log test #generated all possibe log entries diagnose test application dnsproxy 6 #shows the IP addresses of FQDN objects diagnose debug crashlog read #shows crashlog, a status of 0 indicates a normal close of a process!
General Network Troubleshooting
Which is basically ping and traceroute:
execute ping-options ? execute ping-options source <ip-address-of-the-interface> execute ping <hostname|ip> execute ping6-options ? execute ping6 <hostname|ip> execute traceroute <hostname|ip> execute tracert6 <hostname|ip>
Routing
get router info routing-table all #routing table get router info6 routing-table #IPv6 without the "all" keyword get router info kernel #Forwarding Information Base get router info6 kernel get router <routing-protocol> #basic information about the enabled routing protocol diagnose firewall proute list #policy-based routing diagnose firewall proute6 list diagnose ip rtcache list #route cache = current sessions w/ routing information
High Availability
diagnose sys ha status execute ha manage ? #switch to the CLI of a secondary unit execute ha manage <device-index> diagnose sys ha showcsum #verify the checksum of all synchronized peers
Session Table
Display the current active sessions:
get system session list #rough view with NAT, only IPv4 diagnose sys session filter clear diagnose sys session filter ? diagnose sys session filter dst 8.8.8.8 diagnose sys session filter dport 53 diagnose sys session list
Sniffer
Sniff packets like tcpdump does. This can be used for investigating connection problems between two hosts. (There are no details of the firewall policy decisions. Use the debug flow (next paragraph) for anaysis about firewall policies, etc.)
diagnose sniffer packet <interface|any> '<tcpdump-filter>' <verbose> <count> <time-format>
with:
verbose:
1: print header of packets
2: print header and data from ip of packets
3: print header and data from ethernet of packets (if available)
4: print header of packets with interface name
5: print header and data from ip of packets with interface name
6: print header and data from ethernet of packets (if available) with intf name
count: number of packets
time-format:
a: UTC time
l: local time
Examples:
diagnose sniffer packet any 'host 8.8.8.8' 4 4 l diagnose sniffer packet any 'host 8.8.8.8 and dst port 53' 4 10 a diagnose sniffer packet wan1 'dst port (80 or 443)' 2 50 l
Flow
If you want to see the FortiGate details about a connection, use this kind of debug. E.g., it shows the routing decision and the policy, which allowed the connection.
diagnose debug reset diagnose debug flow filter ? diagnose debug flow filter saddr 172.16.27.148 diagnose debug flow filter daddr 8.8.8.8 diagnose debug flow show console enable diagnose debug enable diagnose debug flow trace start 10 #display the next 10 packets, after that, disable the flow: diagnose debug disable
Example:
fd-wv-fw04 # diagnose debug reset fd-wv-fw04 # diagnose debug flow filter daddr 8.8.8.8 fd-wv-fw04 # diagnose debug flow show console enable show trace messages on console fd-wv-fw04 # diagnose debug enable fd-wv-fw04 # diagnose debug flow trace start 20 id=20085 trace_id=11 func=print_pkt_detail line=4420 msg="vd-root received a packet(proto=17, 192.168.160.10:55859->8.8.8.8:53) from fg-trust. " id=20085 trace_id=11 func=init_ip_session_common line=4569 msg="allocate a new session-0001f004" id=20085 trace_id=11 func=vf_ip4_route_input line=1596 msg="find a route: flags=00000000 gw-172.16.1.1 via wan1" id=20085 trace_id=11 func=fw_forward_handler line=671 msg="Allowed by Policy-16:" id=20085 trace_id=11 func=__ip_session_run_tuple line=2601 msg="run helper-dns-udp(dir=original)" id=20085 trace_id=12 func=print_pkt_detail line=4420 msg="vd-root received a packet(proto=17, 192.168.160.10:63624->8.8.8.8:53) from fg-trust. " id=20085 trace_id=12 func=init_ip_session_common line=4569 msg="allocate a new session-0001f005" id=20085 trace_id=12 func=vf_ip4_route_input line=1596 msg="find a route: flags=00000000 gw-172.16.1.1 via wan1" id=20085 trace_id=12 func=fw_forward_handler line=671 msg="Allowed by Policy-16:" id=20085 trace_id=12 func=__ip_session_run_tuple line=2601 msg="run helper-dns-udp(dir=original)" fd-wv-fw04 # diagnose debug disable
VPN
To show details about IKE/IPsec connections, use these commands:
get vpn ike gateway <name> get vpn ipsec tunnel name <name> get vpn ipsec tunnel details diagnose vpn tunnel list get router info routing-table all
And to debug IKE/IPsec sessions, use the VPN debug:
diagnose debug reset diagnose vpn ike log-filter clear diagnose vpn ike log-filter ? diagnose vpn ike log-filter dst-addr4 1.2.3.4 diagnose debug app ike 255 #shows phase 1 and phase 2 output diagnose debug enable #after enough output, disable the debug: diagnose debug disable
Log
For investigating the log entries (similar to the GUI), use the following filters, etc.:
execute log filter reset execute log filter category event execute log filter field #press enter for options execute log filter field dstport 8001 execute log filter view-lines 1000 execute log filter start-line 1 execute log display
Links
- Fortinet: FortiOS 5.2 CLI Reference
- itsecworks: Fortigate troubleshooting commands