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To: iana@isi.edu
Subject: Request for three DHCP option numbers
Date: Mon, 11 Nov 1996 16:35:13 -0500
From: Ralph E. Droms <droms@charcoal.eg.bucknell.edu>
Authentication for DHCP Messages
<draft-ietf-dhc-authentication-03.txt>
(to be submitted)
1. Introduction
DHCP transports protocol stack configuration parameters from
centrally administered servers to TCP/IP hosts. Among those
parameters are an IP address. DHCP servers can be configured to
dynamically allocate addresses from a pool of addresses, eliminating
a manual step in configuration of TCP/IP hosts.
In some situations, network administrators may wish to constrain the
allocation of addresses to authorized hosts. Such constraint may be
desirable in "hostile" environments where the network medium is not
physically secured, such as wireless networks or college residence
halls.
Additionally, some network administrators may wish to provide
authentication of DHCP messages from DHCP servers. In some
environments, clients may be subject to denial of service attacks
through the use of bogus DHCP servers, or may simply be misconfigured
due to unintentionally instantiated DHCP servers.
The goal of this proposal is to suggest a technique through which
authorization tickets can be easily generated and newly attached
hosts with proper authorization can be automatically configured from
an authenticated DHCP server.
2. Format of the authentication option
The following diagram defines the format of the DHCP authentication
option:
+----------+----------+----------+
| Code | Length | Protocol |
+----------+----------+----------+-----------+---
| Authentication information
+----------+----------+----------+-----------+---
The code for the authentication option is 90, and the length field
contains the length of the protocol and authentication information
fields in octets. The protocol field defines the particular
technique for authentication used in the option.
This document defines two protocols in sections 3 and 4, encoded with
protocol field values 0 and 1. Protocol field values 2-254 are
reserved. Other protocols may be defined according to the procedures
described in section 4.
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