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 mathematical 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/freeradius/3.0/radiusd.conf

SEE ALSO

       radiusd(8), radiusd.conf(5)

AUTHOR

       Chris Parker, cparker@segv.org

                                                 5 February 2004                                     rlm_expr(5)