With IPHost Network Monitor you can run simple snmp requests against a Fortinet device in your network.
fnNidsSigUserDefSum
fn Nids Sig User Def Sum
1.3.6.1.4.1.12356.5.1.3.1.2
User defined signature summary
Back to FORTINET-MIB MIB page.
IPHost Network monitor allows you to monitor fnNidsSigUserDefSum on Fortinet device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Fortinet firewalls right now.