Technical Tip: IPv6 probe-response feature

Cloud platforms like Microsoft Azure rely on health probes to determine the availability of backend instances.

For IPv4, FortiGate already supports probe-response.

Prior to FortiOS 7.6.5, the probe-response option was not available for IPv6.

Starting from FortiOS 7.6.5, probe-response support is added for IPv6 interfaces.

This enhancement improves FortiGate compatibility with IPv6-based cloud load balancers and health probes

Behavior in FortiOS 7.6.4 (and earlier):
In an IPv4 interface, probe-response is available.

In FortiOS 7.6.4, probe-response is available under IPv4 interface access settings:

config system interface
    edit port2
        set allowaccess ping https ssh snmp http telnet fgfm radius-acct probe-response fabric ftm speed-test
    next
end

In an IPv6 interface, probe-response is not available.

In the same FortiOS version, IPv6 access settings do not include probe-response:

config system interface
    edit port2
        config ipv6
            set ip6-allowaccess ping https ssh snmp http telnet fgfm fabric
        end
    next
end

Behavior in FortiOS 7.6.5 (and later):

Starting with FortiOS 7.6.5, probe-response is available under IPv6 interface access:

config system interface
    edit port2
        config ipv6
            set ip6-allowaccess ping https ssh snmp http telnet probe-response fgfm fabric
        end
    next
end

This functionality is introduced as a new feature under feature ID 1135850 in FortiOS 7.6.5 and 8.0.0.