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rlm_attr_filter(5)             FreeRADIUS Module            rlm_attr_filter(5)


NAME

       rlm_attr_filter - FreeRADIUS Module


DESCRIPTION

       The rlm_attr_filter module exists for filtering certain attributes and
       values in received ( or transmitted ) radius packets.  It gives the
       server a flexible framework to filter the attributes we send to or
       receive from home servers or NASes.  This makes sense, for example, in
       an out-sourced dialup situation to various policy decisions, such as
       restricting a client to certain ranges of Idle-Timeout or Session-
       Timeout.

       Filter rules are normally defined and applied on a per-realm basis,
       where the realm is anything that is defined and matched based on the
       configuration of the rlm_realm module.  Filter rules can optionally be
       applied using another attribute, by editing the key configuration for
       this module.

       In 2.0.1 and earlier versions, the "accounting" section filtered the
       Accounting-Request, even though it was documented as filtering the
       response.  This issue has been fixed in version 2.0.2 and later
       versions.  The "preacct" section may now be used to filter Accounting-
       Request packets.  The "accounting" section now filters Accounting-
       Response packets.  Administrators using "attr_filter" in the
       "accounting" section SHOULD move the reference to "attr_filter" from
       "accounting" to "preacct".

       The file that defines the attribute filtering rules follows a similar
       syntax to the users file.  There are a few differences however:

                  There are no check-items allowed other than the name of the key.

                  There can only be a single DEFAULT entry.

              The rules for each entry are parsed to top to bottom, and an
              attribute must pass *all* the rules which affect it in order to
              make it past the filter.  Order of the rules is important.
              The operators and their purpose in defining the rules are as
              follows:

              =      THIS OPERATOR IS NOT ALLOWED.  If used, and warning message is
                     printed and it is treated as ==

              :=     Set, this attribute and value will always be placed in the
                     output A/V Pairs.  If the attribute exists, it is overwritten.

              ==     Equal, value must match exactly.

              =*     Always Equal, allow all values for the specified attribute.

              !*     Never Equal, disallow all values for the specified attribute.
                     ( This is redundant, as any A/V Pair not explicitly permitted
                     will be dropped ).

              !=     Not Equal, value must not match.

              >=     Greater Than or Equal

              <=     Less Than or Equal

              >      Greater Than

              <      Less Than

              If regular expressions are enabled the following operators are
              also possible.  ( Regular Expressions are included by default
              unless your system doesn't support them, which should be rare ).
              The value field uses standard regular expression syntax.

              =~     Regular Expression Equal

              !~     Regular Expression Not Equal

              See the default /etc/raddb/attrs for working examples of
              sample rule ordering and how to use the different operators.

       The configuration items are:

       attrsfile
              This specifies the location of the file used to load the filter
              rules.  This file is used to filter the accounting response,
              packet before it is proxied, proxy response from the home
              server, or our response to the NAS.

       key    Usually %{Realm} (the default).  Can also be %{User-Name}, or
              other attribute that exists in the request.  Note that the
              module always keys off of attributes in the request, and NOT in
              any other packet.

       relaxed
              If set to 'yes', then attributes which do not match any filter
              rules explicitly, will also be allowed. This behaviour may be
              overridden for an individual filter block using the Relax-Filter
              check item.  The default for this configuration item is 'no'.


SECTIONS

       preacct
              Filters Accounting-Request packets.

       accounting
              Filters Accounting-Response packets.

       pre-proxy
              Filters Accounting-Request or Access-Request packets prior to
              proxying them.

       post-proxy
              Filters Accounting-Response, Access-Accept, Access-Reject, or
              Access-Challenge responses from a home server.

       authorize
              Filters Access-Request packets.

       post-auth
              Filters Access-Accept or Access-Reject packets.


FILES

       /etc/raddb/radiusd.conf /etc/raddb/attrs


SEE ALSO

       radiusd(8), radiusd.conf(5)


AUTHOR

       Chris Parker, cparker@segv.org

                               12 February 2008             rlm_attr_filter(5)

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