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  over-
	      ridden 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)