1rlm_expr(5)                    FreeRADIUS Module                   rlm_expr(5)
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NAME

6       rlm_expr - FreeRADIUS Module
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DESCRIPTION

9       The  rlm_expr  module allows the server to perform limited mathematical
10       calculations.  This module is not called directly in any section, it is
11       invoked through the dynamic expansion of strings.
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13       For example, some NAS boxes send a NAS-Port attribute which is a 32-bit
14       number composed of port, card, and interface, all in  different  bytes.
15       To see these attributes split into pieces, you can have an entry in the
16       'users' file like:
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18       DEFAULT
19           Vendor-Interface = `%{expr: %{NAS-Port} / (256 * 256)}`,
20           Vendor-Card = `%{expr: (%{NAS-Port} / 256) %% 256}`,
21           Vendor-Port = `%{expr: %{NAS-Port} %% 256}`
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23       where the attributes Vendor-Interface, Vendor-Card, and Vendor-Port are
24       attributes created by either you or a vendor-supplied dictionary.
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26       The mathematical operators supported by the expression module are:
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28       +      addition
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30       -      subtraction
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32       /      division
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34       %%     modulo remainder
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36       *      multiplication
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38       &      boolean AND
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40       |      boolean OR
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42       ()     grouping of sub-expressions
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44       NOTE:  The modulo remainder operator is '%%', and not '%'.  This is due
45       to the '%' character being used as  a  special  character  for  dynamic
46       translation.
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48       NOTE: These operators do NOT have precedence.  The parsing of the input
49       string, and the calculation of the answer, is  done  strictly  left  to
50       right.   If you wish to order the expressions, you MUST group them into
51       sub-expression, as shown in the previous example.
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53       All of the calculations are performed as unsigned 32-bit integers.
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CONFIGURATION

56       modules {
57         ...
58         expr {
59         }
60         ...
61       }
62        ...
63       instantiate {
64         ...
65         expr
66         ...
67       }
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SECTIONS

70       instantiate
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FILES

73       /etc/raddb/radiusd.conf
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SEE ALSO

76       radiusd(8), radiusd.conf(5)
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AUTHOR

79       Chris Parker, cparker@segv.org
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84                                5 February 2004                    rlm_expr(5)