With IPHost Network Monitor you can run simple snmp requests against a Fortinet device in your network.
fgVpnSslStatsActiveTunnels
fg Vpn Ssl Stats Active Tunnels
1.3.6.1.4.1.12356.101.12.2.3.1.6
The current number of active SSL tunnels in the virtual domain
Back to FORTINET-FORTIGATE-MIB MIB page.
IPHost Network monitor allows you to monitor fgVpnSslStatsActiveTunnels on Fortinet device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Fortinet WAN extenders right now.