With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
tn3270eTcpConnLastActivity
tn3270e Tcp Connection Last Activity
1.3.6.1.2.1.34.8.1.9.1.7
The number of 100ths of seconds since any data was transferred for the associated TCP Connection.
Back to TN3270E-MIB MIB page.
IPHost Network monitor allows you to monitor tn3270eTcpConnLastActivity on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco firewalls right now.