With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
natStatsInterfaceGroup
nat Stats Interface Group
1.3.6.1.2.1.123.2.1.3
A collection of NAT statistics associated with the interface on which NAT is configured, to aid troubleshooting/monitoring of the NAT operation.
Back to NAT-MIB MIB page.
IPHost Network monitor allows you to monitor natStatsInterfaceGroup 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.