A Threat Level may be activated or cleared using a custom IO Linker Rule. Typically the Custom IO Linker Rule will be associated with an input on a VertX controller.

Required Configuration Modifications
The VertX configuration file /etc/iolinker.conf must be modified to extend the I/O Linker command definitions. An example of the iolinker.conf file is shown below:

#I/O Linker Commands Definitions
#command: path arguments
HTTP: /mnt/apps/bin/write_http "$1"
TCP: /mnt/apps/bin/write_tcp -h $1 -p $2 -m "$3"
SERIAL: /mnt/apps/bin/write_serial -d /dev/$1 -b $2 -p $3 -s $4 -a 8 -m "$5"
ALERT: /mnt/apps/bin/alert /mnt/data/db/vdb /mnt/data/db/carddb $1 $2 "$3;$4;$5;"
MSG: echo "$1" > /tmp/postaccessreq

The line at the bottom (MSG: echo "$1" > /tmp/postaccessreq) will add the behavior required to write a message into the named pipe that the post access processor task reads at runtime.

**Notes
• The IO Linker task must be restarted after modification of the iolinker.conf configuration file.

Example Custom IO Linker Rule
Example:

MSG("0093;0059;3;1;Threat Level 1;External Input;IO Linker Rule;") = I(00,21)

Where:
• MSG(...) - is the I/O Linker command extension (added above).

Elements within the MSG() I/O Linker Command Extension (each must be separated with the semi-colon “;”):

• 0093 – A constant value that defines a message to the PostAccessProcessor task.
• 0059 – The number of all characters within the quotes.
• 3 – A constant value of 3 that defines the sub command, Set Threat Level, used within the PostAccessProcessor task.
• 1 - The Threat Level ID (Get this value from the database, see the[ThreatLevelID]field from the [OFS].[Application].[ThreatLevels] table). Note that a value of “0” will “clear” any currently activate threat level.
• Threat Level 1 – The description of the Threat Level to activate. See the[Description]field from the [OFS].[Application].[ThreatLevels] table.
• External Input – Name of the input. Used when logging the “where activated” portion of the Threat Level Activated event.
• IO Linker Rule – Used when logging the “who activated” portion of the Threat Level Activated event.

RHS (what triggers the IO Linker Rule):

• I(00,21) – The input used to activate the threat level. In this example, the AC Failure input is used to activate the Threat Level.