Looking for help/advice with the following problem: We have an ASA5520 running ver 7.0(8), nat-control is disabled. On the "outside" interface we have a closed network which is publicly addressed i.e. no access to Internet. We also have two Vlan interfaces on a trunk connection i.e. "inside" interface (Vlan7) and "dmz" interface (Vlan802). Traffic from the "outside" to "inside" is statically NAT'd such that the public IP is translated to a private IP when accessing the "inside" interface. However, our OSS servers on the "dmz" interface need to be able to receive packets from the public IP addresses on the "outside" . All is okay with the outside to inside traffic and traffic initiated from the OSS servers on the "dmz" to the outside works okay (snmp gets etc) i.e. the servers receive reply packets from the public addresses of the outside devices.
However, traffic that originates on the "outside" interface (snmp traps etc) which is destined for the "dmz" is actually being routed to the "inside" interface and therefore the public source address is being NAT'd by the static NAT command. The access-list "in_on_outside" has relevant entries to allow connectivity from outside to dmz, we have tried a static nat command (outside, dmz) to maintain the public addressing but this made no difference and also a nat exempt.