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rlm_expr(5)                                   FreeRADIUS Module                                  rlm_expr(5)



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




                                               5 February 2004                                   rlm_expr(5)