Tuesday, November 29, 2011

Notes on Suricata 1.1 Update

A few quick notes on the Suricata 1.1 update and its default suricata.yaml configuration file:

decoder-events.rules and stream-events.rules
By default, suricata.yaml includes the following rules:
 - decoder-events.rules
 - stream-events.rules

This results in alerts like these:
Suricata stream events example
If you don't wish to see these alerts, simply comment out those two rules in /etc/nsm/NAME-OF-SENSOR/suricata.yaml and restart Suricata.

By default, suricata.yaml sets EXTERNAL_NET to "!HOME_NET".  (The Snort default in snort.conf is "EXTERNAL_NET any".)  If you'd like to change this, simply make the change in /etc/nsm/NAME-OF-SENSOR/suricata.yaml and restart Suricata.

How do I edit suricata.yaml and restart Suricata?
If you have GUI access to your sensor, you can use the "IDS Config" menu entry as described here:

Otherwise, you can do the following:

  • Modify /etc/nsm/NAME-OF-SENSOR/suricata.yaml using your favorite text editor.
  • Restart Suricata using the following command:
    sudo nsm --sensor --restart --only-snort-alert

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