RFC 2868 (rfc2868) - Page 2 of 20
RADIUS Attributes for Tunnel Protocol Support
Alternative Format: Original Text Document
RFC 2868 RADIUS Tunnel Authentication Attributes June 2000
2. Specification of Requirements
In this document, the key words "MAY", "MUST, "MUST NOT", "optional",
"recommended", "SHOULD", and "SHOULD NOT", are to be interpreted as
described in [14].
3. Attributes
Multiple instances of each of the attributes defined below may be
included in a single RADIUS packet. In this case, the attributes to
be applied to any given tunnel SHOULD all contain the same value in
their respective Tag fields; otherwise, the Tag field SHOULD NOT be
used.
If the RADIUS server returns attributes describing multiple tunnels
then the tunnels SHOULD be interpreted by the tunnel initiator as
alternatives and the server SHOULD include an instance of the
Tunnel-Preference Attribute in the set of Attributes pertaining to
each alternative tunnel. Similarly, if the RADIUS client includes
multiple sets of tunnel Attributes in an Access-Request packet, all
the Attributes pertaining to a given tunnel SHOULD contain the same
value in their respective Tag fields and each set SHOULD include an
appropriately valued instance of the Tunnel-Preference Attribute.
3.1. Tunnel-Type
Description
This Attribute indicates the tunneling protocol(s) to be used (in
the case of a tunnel initiator) or the the tunneling protocol in
use (in the case of a tunnel terminator). It MAY be included in
Access-Request, Access-Accept and Accounting-Request packets. If
the Tunnel-Type Attribute is present in an Access-Request packet
sent from a tunnel initiator, it SHOULD be taken as a hint to the
RADIUS server as to the tunnelling protocols supported by the
tunnel end-point; the RADIUS server MAY ignore the hint, however.
A tunnel initiator is not required to implement any of these
tunnel types; if a tunnel initiator receives an Access-Accept
packet which contains only unknown or unsupported Tunnel-Types,
the tunnel initiator MUST behave as though an Access-Reject had
been received instead.
If the Tunnel-Type Attribute is present in an Access-Request
packet sent from a tunnel terminator, it SHOULD be taken to
signify the tunnelling protocol in use. In this case, if the
RADIUS server determines that the use of the communicated protocol
is not authorized, it MAY return an Access-Reject packet. If a
tunnel terminator receives an Access-Accept packet which contains
Zorn, et al. Informational