Section: FreeRADIUS Module (5)
Updated: 3 February 2004
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rlm_attr_filter - FreeRADIUS Module
The rlm_attr_filter module exists for filtering certain
attributes and values in received ( or transmitted ) radius packets
from ( or to ) remote proxy servers. It gives the proxier ( us ) a
flexible framework to filter the attributes we send to or receive
from these remote proxies. 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
Filter rules are 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.
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 realm.
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
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
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 main configuration item is:
This specifies the location of the file used to load the filter rules.
Chris Parker, email@example.com
- SEE ALSO
linux.jgfs.net manual pages