Use the check boxes within the Aggressive Mode section of the Security tab to specify whether the Slave outstation (ClearSCADA) is to accept or issue requests using Aggressive Mode:
- Accept Requests—Select this check box if the Slave outstation (ClearSCADA) is to accept Aggressive Mode requests from its DNP3 master(s). With such requests, the DNP3 master includes the necessary authentication data in the same message as the critical request.
- Clear the Accept Requests check box if the Slave outstation is to reject any Aggressive Mode requests that it receives from its DNP3 master(s). The Slave outstation may also send a diagnostics message indicating that it does not accept Aggressive Mode requests (see Specify the Maximum Error Count).
- Issue Requests—Select this check box if the Slave outstation (ClearSCADA) is to send Aggressive Mode responses to its DNP3 master(s). With such responses, the Slave outstation includes the necessary authentication data in the same message as the critical response.
- Clear the Issue Requests check box if the Slave outstation is not to send Aggressive Mode responses. The DNP3 master(s) will challenge any critical responses that they receives from this Slave outstation.
If the Slave outstation issues an Aggressive Mode response to a DNP3 master that does not accept Aggressive Mode responses, the DNP3 master will generate an error (providing that the DNP3 master has not exceeded its maximum error count). On detecting such an error, the Slave outstation will send responses to subsequent requests, and issue any unsolicited messages, without using Aggressive Mode. As such, the Slave outstation will expect the DNP3 master to challenge such responses. The Slave outstation will not use Aggressive Mode for any other responses that it sends to the DNP3 master.
Should such a security conflict occur, correct the configuration in the relevant device so that the appropriate mode of DNP3 Secure Authentication is used. (If the configuration is not corrected, the Slave outstation will attempt to issue further Aggressive Mode responses should, for example, a Main-Standby changeover occur, the driver restart, or another configuration change be made.)