RADIUS attribute from rfc5090
This attribute is a placeholder for future extensions and
corresponds to the auth-param parameter defined in. The Digest-Auth-Param is the mechanism
whereby the RADIUS client and RADIUS server can exchange auth-
param extension parameters contained within Digest headers that
are not understood by the RADIUS client and for which there are
no corresponding stand-alone attributes.
Unlike the previously listed Digest-* attributes, the Digest-
Auth-Param contains not only the value but also the parameter
name, since the parameter name is unknown to the RADIUS client.
If the Digest header contains several unknown parameters, thenthe RADIUS implementation MUST repeat this attribute, and each
instance MUST contain one different unknown Digest
parameter/value combination. This attribute MUST ONLY be used
in Access-Request, Access-Challenge, Access-Accept, and
117 for Digest-Auth-Param
The text consists of the whole parameter, including its name,
the equal sign ('='), and quotes.