@ -1,7 +1,7 @@
.. _exception policies:
Exception Policies
==================
##################
Suricata has a set of configuration variables to indicate what should the engine
do when certain exception conditions, such as hitting a memcap, are reached.
@ -16,13 +16,10 @@ For developers or for researching purposes, there are also simulation options
exposed in debug mode and passed via command-line. These exist to force or
simulate failures or errors and understand Suricata behavior under such conditions.
Exception Policies
------------------
.. _master-switch:
Master Switch
~~~~~~~~~~~~~
***** ***** ***
It is possible to set all configuration policies via what we call "master
switch". This offers a quick way to define what the engine should do in case of
@ -46,7 +43,7 @@ This value will be overwritten by specific exception policies whose settings are
also defined in the yaml file.
Auto
''''
====
**In IPS mode** , the default behavior for most of the exception policies is to
fail close. This means dropping the flow, or the packet, when the flow action is
@ -66,7 +63,7 @@ It is possible to disable this default, by setting the exception policies'
.. _eps_settings:
Specific settings
~~~~~~~~~~~~~~~~~
***** ***** ***** **
Exception policies are implemented for:
@ -132,7 +129,7 @@ The *drop*, *pass* and *reject* are similar to the rule actions described in :re
actions<suricata-yaml-action-order>`.
Exception Policies and Midstream Pick-up Sessions
-------------------------------------------------
***** ***** ***** ***** ***** ***** ***** ***** ***** *** *
Suricata behavior can be difficult to track in case of midstream session
pick-ups. Consider this matrix illustrating the different interactions for
@ -214,17 +211,18 @@ whole flow.
Notes:
* Not valid means that Suricata will error out and won't start.
* `` REJECT `` will make Suricata send a Reset-packet unreach error to the sender of the matching packet.
* `` REJECT `` will make Suricata send a Reset-packet unreach error to the sender
of the matching packet.
.. _eps_output:
Log Output
----------
***** *****
.. _eps_flow_event:
Flow Event
~~~~~~~~~~
==========
When an Exception Policy is triggered, this will be indicated in the flow log
event for the associated flow, also indicating which target triggered that, and
@ -266,7 +264,7 @@ exception policy, but that is set up to ``ignore``::
.. _eps_stats:
Available Stats
~~~~~~~~~~~~~~~
===============
There are stats counters for each supported exception policy scenario that will
be logged when exception policies are enabled:
@ -303,7 +301,7 @@ temporarily (for more, read :ref:`stats configuration<suricata_yaml_outputs>`).
Command-line Options for Simulating Exceptions
----------------------------------------------
==============================================
It is also possible to force specific exception scenarios, to check engine
behavior under failure or error conditions.