With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cpaeUserGroupUserName
Cisco Port Access Entity User Group User Name
1.3.6.1.4.1.9.9.220.1.5.1.3
Specifies the name of the user authenticated on a port of the device.
Back to CISCO-PAE-MIB MIB page.
IPHost Network monitor allows you to monitor cpaeUserGroupUserName on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco routers right now.