rlm_expr(5) FreeRADIUS Module rlm_expr(5)NAMErlm_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 ALSOradiusd(8), radiusd.conf(5)AUTHOR
Chris Parker, cparker@segv.org
5 February 2004 rlm_expr(5)
