doc/userguide/rules/ip-reputation-rules.rst
IP Reputation can be used in rules through a new rule keyword "iprep".
For more information about IP Reputation see :doc:/reputation/ipreputation/ip-reputation-config and :doc:/reputation/ipreputation/ip-reputation-format.
The iprep directive matches on the IP reputation information for a host.
::
iprep:<side to check>,<category>,<operator>,<reputation score>
side to check: <any|src|dst|both>
category: the category short name
operator: <, <=, >, >=, =
reputation score: 0-127
Example:
::
alert ip $HOME_NET any -> any any (msg:"IPREP internal host talking to CnC server"; flow:to_server; iprep:dst,CnC,>,30; sid:1; rev:1;)
This rule will alert when a system in $HOME_NET acts as a client while communicating with any IP in the CnC category that has a reputation score set to greater than 30.
isset and isnotset
``isset`` and ``isnotset`` can be used to test reputation "membership"
::
iprep:<side to check>,<category>,<isset|issnotset>
``side to check``: <any|src|dst|both>
``category``: the category short name
To test whether an IP is part of an iprep set at all, the ``isset`` can be used. It acts as a ``>=,0`` statement.
.. container:: example-rule
drop ip $HOME_NET any -> any any (:example-rule-options:`iprep:src,known-bad-hosts,isset;` sid:1;)
In this example traffic to any IP with a score in ``known-bad-hosts`` would be blocked.
``isnotset`` can be used to test if an IP is not a part of the set.
.. container:: example-rule
drop ip $HOME_NET any -> any any (:example-rule-options:`iprep:src,trusted-hosts,isnotset;` sid:1;)
In this example traffic for a host w/o a trust score would be blocked.
Compatibility with IP-only
The "iprep" keyword is compatible with "IP-only" rules. This means that a rule like:
::
alert ip any any -> any any (msg:"IPREP High Value CnC"; iprep:src,CnC,>,100; sid:1; rev:1;)
will only be checked once per flow-direction.