With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cnatConfTable
cnat Config Table
1.3.6.1.4.1.9.10.77.1.1.1
This table specifies the configuration attributes for a device supporting NAT function.
Back to CISCO-IETF-NAT-MIB MIB page.
IPHost Network monitor allows you to monitor cnatConfTable 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.