rlm_expr

Section: FreeRADIUS Module (5)
Updated: 5 February 2004
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NAME

rlm_expr - FreeRADIUS Module  

DESCRIPTION

The rlm_expr module allows the server to perform limited mathematical calculations. This module is not called directly in any section, it is invoked through the dynamic expansion of strings.

For example, some NAS boxes send a NAS-Port attribute which is a 32-bit number composed of port, card, and interface, all in different bytes. To see these attributes split into pieces, you can have an entry in the 'users' file like:


DEFAULT

Vendor-Interface = `%{expr: %{NAS-Port} / (256 * 256)}`,
Vendor-Card = `%{expr: (%{NAS-Port} / 256) %% 256}`,
Vendor-Port = `%{expr: %{NAS-Port} %% 256}`

where the attributes Vendor-Interface, Vendor-Card, and Vendor-Port are attributes created by either you or a vendor-supplied dictionary.

The methematical operators supported by the expression module are:

+
addition
-
subtraction
/
division
%%
modulo remainder
*
multiplication
&
boolean AND
|
boolean OR
()
grouping of sub-expressions

NOTE: The modulo remainder operator is '%%', and not '%'. This is due to the '%' character being used as a special character for dynamic translation.

NOTE: These operators do NOT have precedence. The parsing of the input string, and the calculation of the answer, is done strictly left to right. If you wish to order the expressions, you MUST group them into sub-expression, as shown in the previous example.

All of the calculations are performed as unsigned 32-bit integers.

 

CONFIGURATION


modules {
  ...

expr {
}
...
}
...
instantiate { ...
expr ...
}
 

SECTIONS

instantiate

 

FILES

/etc/raddb/radiusd.conf

 

SEE ALSO

radiusd(8), radiusd.conf(5)  

AUTHOR

Chris Parker, cparker@segv.org


 

Index

NAME
DESCRIPTION
CONFIGURATION
SECTIONS
FILES
SEE ALSO
AUTHOR

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Time: 17:17:31 GMT, February 06, 2011