NATStat is simple NATDet logs parser. Use it with large files.
Usage example:

(root@osiris ~/natdet/natstat)# ./natstat ../nat-eth1.log
NATDet started 20:22:57 04-03-2005
192.168.0.69    NAT detected with 100% accuracy (for 1 systems)
192.168.0.1     NAT detected with 100% accuracy (for 3 systems)
192.168.0.19    NAT detected with  89% accuracy (for 2 systems)

