Removing a Sensor

There may come a time when you need to disable a sensor interface, delete a sensor’s configuration, or get rid of an entire sensor and its data altogether. The steps below outline what is required to accomplish each objective.

Disable sensor interface

To disable a sensor interface:

stop all sensor processes:

sudo so-sensor-stop

edit /etc/nsm/sensortab and comment out the sensor interface line
edit /opt/bro/etc/node.cfg and comment out the sensor interface stanza
start all sensor processes:

sudo so-sensor-start

Delete sensor configuration

To delete the configuration for a sensor, run /usr/sbin/nsm_sensor_del on the sensor box for which you wish to delete the configuration.

Wipe sensor configuration and data

To completely wipe sensor configuration and data, run sudo sosetup on the sensor box for which you wish to wipe the data and configuration.

Remove sensor reference from master server

In MySQL database securityonion_db, edit sensor table (you can simply set active=’N’), then restart sguild.
Stop sguild sudo so-sensor-stop
Show sensor entries:

sudo mysql --defaults-file=/etc/mysql/debian.cnf -Dsecurityonion_db -e 'select * from sensor';

Set sensor as inactive:

sudo mysql --defaults-file=/etc/mysql/debian.cnf -Dsecurityonion_db -e "update sensor set active='N' where sid in (<SID1>,<SID2>)";

Start sguild:

sudo so-sensor-start

If running salt, remove the sensor from /opt/onionsalt/salt/top.sls and then delete the key from salt:

sudo salt-key -d sensor_key_name

PLEASE NOTE: This step is only required if you are still running ELSA. ELSA reached EOL on October 9, 2018. On the master server, edit /etc/elsa_web.conf, remove the sensor from the peers section, then restart Apache (sudo service apache2 restart).

Remove storage node reference from Master server Elasticsearch _cluster/settings

From Kibana, navigate to Dev Tools and paste the following text into the window (modifying nodename to match the name of your node):

PUT _cluster/settings
{
  "persistent": {
    "search": {
      "remote": {
        "nodename": {
          "skip_unavailable": null,
          "seeds":null
        }
      }
    }
  }
}

Click the play button to send the request to Elasticsearch.