8.23. DNP3 Keywords

The DNP3 keywords can be used to match on fields in decoded DNP3 messages. The keywords are based on Snort's DNP3 keywords and aim to be 100% compatible.

8.23.1. dnp3_func

This keyword will match on the application function code found in DNP3 request and responses. It can be specified as the integer value or the symbolic name of the function code.

dnp3_func uses an unsigned 8-bits integer.

8.23.1.1. Syntax

dnp3_func:<value>;

Where value is one of:

An integer value between 0 and 255 inclusive.
Function code name:
- confirm
- read
- write
- select
- operate
- direct_operate
- direct_operate_nr
- immed_freeze
- immed_freeze_nr
- freeze_clear
- freeze_clear_nr
- freeze_at_time
- freeze_at_time_nr
- cold_restart
- warm_restart
- initialize_data
- initialize_appl
- start_appl
- stop_appl
- save_config
- enable_unsolicited
- disable_unsolicited
- assign_class
- delay_measure
- record_current_time
- open_file
- close_file
- delete_file
- get_file_info
- authenticate_file
- abort_file
- activate_config
- authenticate_req
- authenticate_err
- response
- unsolicited_response
- authenticate_resp

8.23.2. dnp3_ind

This keyword matches on the DNP3 internal indicator flags in the response application header.

dnp3_ind uses an unsigned 16-bits integer with bitmasks.

8.23.2.1. Syntax

dnp3_ind:[*+-=]<flag>{,<flag>...}

Where flag is the name of the internal indicator:

all_stations
class_1_events
class_2_events
class_3_events
need_time
local_control
device_trouble
device_restart
no_func_code_support
object_unknown
parameter_error
event_buffer_overflow
already_executing
config_corrupt
reserved_2
reserved_1

This keyword will match of any of the flags listed are set. To match on multiple flags use prefix +.

8.23.2.2. Examples

dnp3_ind:all_stations;

dnp3_ind:class_1_events,class_2_events;

8.23.3. dnp3_obj

This keyword matches on the DNP3 application data objects.

8.23.3.1. Syntax

dnp3_obj:<group>,<variation>

Where <group> and <variation> are integer values between 0 and 255 inclusive.

8.23.4. dnp3_data

This keyword will cause the following content options to match on the re-assembled application buffer. The reassembled application buffer is a DNP3 fragment with CRCs removed (which occur every 16 bytes), and will be the complete fragment, possibly reassembled from multiple DNP3 link layer frames.

8.23.4.1. Syntax

dnp3_data;

8.23.4.2. Example

dnp3_data; content:"|c3 06|";