draft-ietf-dhc-options-cont-00.txt   draft-ietf-dhc-options-cont-01.txt 
Network Working Group William A. Arbaugh Network Working Group William A. Arbaugh
INTERNET DRAFT Angelos D. Keromytis Internet Draft Angelos D. Keromytis
University of Pennsylvania Expires in sixth months University of Pennsylvania
November 1997 January 2000
Expires May 1998
DHCP Continuation Option Code DHCP Continuation Option Code
<draft-ietf-dhc-options-cont-00.txt> <draft-ietf-dhc-options-cont-01.txt>
Status of this memo Status of this memo
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Abstract Abstract
The Dynamic Host Configuration Protocol (DHCP) provides a framework The Dynamic Host Configuration Protocol (DHCP) provides a framework
for passing configuration information to hosts on a TCP/IP network. for passing configuration information to hosts on a TCP/IP network.
Currently options are limited to an information size of 256 bytes Currently options are limited to an information size of 256 bytes
because of the one-octet size of the length field. This document because of the one-octet size of the length field. This document
defines a new option that permits the continuation of the previous defines a new option that permits the continuation of the previous
option information. option information.
skipping to change at page 2, line 4 skipping to change at line 59
network. Configuration parameters and other control information are network. Configuration parameters and other control information are
carried in tagged data items that are stored in the 'options' field carried in tagged data items that are stored in the 'options' field
of the DHCP message. The data items themselves are also called of the DHCP message. The data items themselves are also called
"options." "options."
Each option is assigned a one-octet option code and an one-octet size Each option is assigned a one-octet option code and an one-octet size
field. The one-octet size field limits the information contained in field. The one-octet size field limits the information contained in
an option to 256 bytes. While there exist options that permit the use an option to 256 bytes. While there exist options that permit the use
of the sname and file fields of the header, these options only add an of the sname and file fields of the header, these options only add an
additional 192 bytes when the fields are not in use. This document additional 192 bytes when the fields are not in use. This document
DRAFT DHCP Continuation Option Code November 1997
describes a new DHCP option for continuing the information from the describes a new DHCP option for continuing the information from the
previous option. This option MUST not appear as the first option in previous option. This option MUST not appear as the first option in
a message. The option preceding this one MUST have a size of 256 a message. The option preceding this one MUST have a size of 256
bytes. bytes.
2. Definition of option [TBD] 2. Definition of option [TBD]
Option code [TBD] indicates that the data contained in the option is Option code [TBD] indicates that the data contained in the option is
a continuation of the previous option. a continuation of the previous option.
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Auth Auth
Code Len option Data... Code Len option Data...
+-----+-----+-----+-----+-----+-----+-------------- +-----+-----+-----+-----+-----+-----+--------------
| 90 | 256 | 04 | d1 d2 d4 ... d255 | 90 | 256 | 04 | d1 d2 d4 ... d255
+-----+-----+-----+-----+-----+-----+--------------- +-----+-----+-----+-----+-----+-----+---------------
Code Len Data... Code Len Data...
+-----+-----+-----+-----+-----+-----+-------------- +-----+-----+-----+-----+-----+-----+--------------
| TBD | 20 | d257 d258 d259 d260 ... d276 | TBD | 20 | d257 d258 d259 d260 ... d276
+-----+-----+-----+-----+-----+-----+--------------- +-----+-----+-----+-----+-----+-----+---------------
4. References 3. References
[1] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, [1] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
Bucknell University, March 1997. Bucknell University, March 1997.
[2] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor [2] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, Lachman Associates, March 1997. Extensions", RFC 2132, Lachman Associates, March 1997.
5. Security Considerations 4. Security Considerations
DHCP currently provides no authentication or security mechanisms. DHCP currently provides no authentication or security mechanisms.
Potential exposures to attack are discussed in section 7 of the DHCP Potential exposures to attack are discussed in section 7 of the DHCP
protocol specification [1]. One of the reasons for this definition is protocol specification [1]. One of the reasons for this definition is
to provide support for the exchange of public key certificates are to provide support for the exchange of public key certificates are
which usually larger than 256 bytes. which usually larger than 256 bytes.
DRAFT DHCP Continuation Option Code November 1997 5. Authors' Address
6. Author's Address
William A. Arbaugh William A. Arbaugh
Angelos D. Keromytis Angelos D. Keromytis
Distributed Systems Lab -- 102 Moore Distributed Systems Lab -- 102 Moore
Department of Computer and Information Sciences Department of Computer and Information Sciences
University of Pennsylvania University of Pennsylvania
200 South 33rd St. 200 South 33rd St.
Philadelphia, PA. 19104-6389 Philadelphia, PA. 19104-6389
Email: {waa, angelos}@dsl.cis.upenn.edu Email: {waa, angelos}@dsl.cis.upenn.edu
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