Configuring the Modbus Preprocessor

Note

This section applies to Snort 2 preprocessors. For information on Snort 3 inspectors, see https://www.cisco.com/go/snort3-inspectors.

You should not enable this preprocessor in a network analysis policy that you apply to traffic if your network does not contain any Modbus-enabled devices.

Procedure

Step 1

Choose Policies > Access Control heading > Access Control, then click Network Analysis Policy or Policies > Access Control heading > Intrusion, then click Network Analysis Policies.

Note

If your custom user role limits access to the first path listed here, use the second path to access the policy.

Step 2

Click Snort 2 Version next to the policy you want to edit.

Step 3

Click Edit (edit icon) next to the policy you want to edit.

If View (View button) appears instead, the configuration belongs to an ancestor domain, or you do not have permission to modify the configuration.

Step 4

Click Settings in the navigation panel.

Step 5

If Modbus Configuration under SCADA Preprocessors is disabled, click Enabled.

Step 6

Click Edit (edit icon) next to Modbus Configuration.

Step 7

Enter a value in the Ports field.

Separate multiple values with commas.

Step 8

To save changes you made in this policy since the last policy commit, click Policy Information, then click Commit Changes.

If you leave the policy without committing changes, cached changes since the last commit are discarded if you edit a different policy.

What to do next