With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cnatConfDynGlobalAddrTo
cnat Config Dyn Global Address To
1.3.6.1.4.1.9.10.77.1.1.3.1.8
This object specifies the last IP address of the range of IP addresses being mapped to.
Back to CISCO-IETF-NAT-MIB MIB page.
IPHost Network monitor allows you to monitor cnatConfDynGlobalAddrTo 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.