ORA-12592 generated when trying to select or view data from dba_audit_trail view.
In addition, ORA-12569: TNS:packet checksum failure maybe generated.
Issue happens in SQL*Plus, as well as Toad.
An ill-formed packet has been detected by the TNS software and /or the data received is not the same as the data sent.
Contact Oracle Customer Support.
Oracle believes it may be a firewall/NAT issue since IP address is embedded in the data. In addition, it maybe picking the internal IP address up and converting it to external IP address causing a checksum error.