Technical Tip: Keeping an active session when 'Schedule expiration' is disabled

[irodriguez_FTNT]

Description

This article describes that with the firewall policy rule setting 'set schedule-timeout enable', a FortiGate immediately forces the session to end when the 'Stop Time' of a recurring 'schedule' object is reached.

Additional configuration steps are required to keep the session active until is finished or expired.

Scope

FortiGate.

Solution

Disabling the schedule-timeout would allow the session to remain open after the schedule has expired. The session will end by a time-out or if any FIN or RST are seen. 

For example, in an office environment, YouTube use is allowed between noon and 2 PM. During that time, any YouTube traffic continues. As long as that session is open, after 2 PM end time, the existing YouTube traffic can continue, yet new sessions will be blocked. With setting 'set schedule-timeout enable', 

FortiGate will terminate all the sessions when the end time of the schedule is reached. 

Through the CLI, the firewall policy firewall-session-dirty option is only available after changing the system settings:

1. Edit system settings:

config system settings
    set firewall-session-dirty check-policy-option
end

2. Edit the firewall policy rule:

config firewall policy
    edit <ID of the policy>
        set schedule-timeout disable

        set firewall-session-dirty check-new
end

The status of the session will change to 'persistent' once the end time of the schedule is reached and the traffic continues flowing.

Related documents: 

CLI Guide - system settings

CLI Guide - firewall policy