We have a lot of messages about land attack in our ASA (5540) firewall:
ASA-2-106017: Deny IP due to Land Attack from A.B.C.149 to A.B.C.149
A.B.C.149 is public IP address for about 32 local IP that PATed to it.
Proxy ARP is enabled on outside and two inside interfaces. Topology is attached.