1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
|
Network Working Group S. Drach
Request for Comments: 2485 Sun Microsystems
Category: Standards Track January 1999
DHCP Option for The Open Group's User Authentication Protocol
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (1999). All Rights Reserved.
Abstract
This document defines a DHCP [1] option that contains a list of
pointers to User Authentication Protocol servers that provide user
authentication services for clients that conform to The Open Group
Network Computing Client Technical Standard [2].
Introduction
The Open Group Network Computing Client Technical Standard, a product
of The Open Group's Network Computing Working Group (NCWG), defines a
network computing client user authentication facility named the User
Authentication Protocol (UAP).
UAP provides two levels of authentication, basic and secure. Basic
authentication uses the Basic Authentication mechanism defined in the
HTTP 1.1 [3] specification. Secure authentication is simply basic
authentication encapsulated in an SSLv3 [4] session.
In both cases, a UAP client needs to obtain the IP address and port
of the UAP service. Additional path information may be required,
depending on the implementation of the service. A URL [5] is an
excellent mechanism for encapsulation of this information since many
UAP servers will be implemented as components within legacy HTTP/SSL
servers.
Drach Standards Track [Page 1]
RFC 2485 DCHP Option for the Open Group's UAP January 1999
Most UAP clients have no local state and are configured when booted
through DHCP. No existing DHCP option [6] has a data field that
contains a URL. Option 72 contains a list of IP addresses for WWW
servers, but it is not adequate since a port and/or path can not be
specified. Hence there is a need for an option that contains a list
of URLs.
User Authentication Protocol Option
This option specifies a list of URLs, each pointing to a user
authentication service that is capable of processing authentication
requests encapsulated in the User Authentication Protocol (UAP). UAP
servers can accept either HTTP 1.1 or SSLv3 connections. If the list
includes a URL that does not contain a port component, the normal
default port is assumed (i.e., port 80 for http and port 443 for
https). If the list includes a URL that does not contain a path
component, the path /uap is assumed.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Length | URL list
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Code 98
Length The length of the data field (i.e., URL list) in
bytes.
URL list A list of one or more URLs separated by the ASCII
space character (0x20).
References
[1] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997.
[2] Technical Standard: Network Computing Client, The Open Group,
Document Number C801, October 1998.
[3] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., and T.
Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC
2068, January 1997.
[4] Freier, A., Karlton, P., and P. Kocher, "The SSL Protocol,
Version 3.0", Netscape Communications Corp., November 1996.
Standards Information Base, The Open Group,
http://www.db.opengroup.org/sib.htm#SSL_3.
Drach Standards Track [Page 2]
RFC 2485 DCHP Option for the Open Group's UAP January 1999
[5] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
Resource Locators (URL)", RFC 1738, December 1994.
[6] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.
Security Considerations
DHCP currently provides no authentication or security mechanisms.
Potential exposures to attack are discussed in section 7 of the DHCP
protocol specification.
The User Authentication Protocol does not have a means to detect
whether or not the client is communicating with a rogue
authentication service that the client contacted because it received
a forged or otherwise compromised UAP option from a DHCP service
whose security was compromised. Even secure authentication does not
provide relief from this type of attack. This security exposure is
mitigated by the environmental assumptions documented in the Network
Computing Client Technical Standard.
Author's Address
Steve Drach
Sun Microsystems, Inc.
901 San Antonio Road
Palo Alto, CA 94303
Phone: (650) 960-1300
EMail: drach@sun.com
Drach Standards Track [Page 3]
RFC 2485 DCHP Option for the Open Group's UAP January 1999
Full Copyright Statement
Copyright (C) The Internet Society (1999). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Drach Standards Track [Page 4]
|
