Network Working Group T. Ylonen
Internet-Draft T. Kivinen
Expires: January 18, 2002 SSH Communications Security Corp
M. Saarinen
University of Jyvaskyla
T. Rinne
S. Lehtinen
SSH Communications Security Corp
July 20, 2001
SSH Protocol Architecture
draft-ietf-secsh-architecture-09.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other
documents at any time. It is inappropriate to use Internet-Drafts
as reference material or to cite them other than as "work in
progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on January 18, 2002.
Copyright Notice
Copyright (C) The Internet Society (2001). All Rights Reserved.
Abstract
SSH is a protocol for secure remote login and other secure network
services over an insecure network. This document describes the
architecture of the SSH protocol, as well as the notation and
terminology used in SSH protocol documents. It also discusses the
SSH algorithm naming system that allows local extensions. The SSH
Ylonen, et. al. Expires January 18, 2002 [Page 1]
Internet-Draft SSH Protocol Architecture July 2001
protocol consists of three major components: The Transport Layer
Protocol provides server authentication, confidentiality, and
integrity with perfect forward secrecy. The User Authentication
Protocol authenticates the client to the server. The Connection
Protocol multiplexes the encrypted tunnel into several logical
channels. Details of these protocols are described in separate
documents.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Specification of Requirements . . . . . . . . . . . . . . . . 3
3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1 Host Keys . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.2 Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 5
3.3 Policy Issues . . . . . . . . . . . . . . . . . . . . . . . . 5
3.4 Security Properties . . . . . . . . . . . . . . . . . . . . . 6
3.5 Packet Size and Overhead . . . . . . . . . . . . . . . . . . . 6
3.6 Localization and Character Set Support . . . . . . . . . . . . 7
4. Data Type Representations Used in the SSH Protocols . . . . . 8
5. Algorithm Naming . . . . . . . . . . . . . . . . . . . . . . . 10
6. Message Numbers . . . . . . . . . . . . . . . . . . . . . . . 11
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
9. Trademark Issues . . . . . . . . . . . . . . . . . . . . . . . 12
10. Additional Information . . . . . . . . . . . . . . . . . . . . 12
References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 14
Full Copyright Statement . . . . . . . . . . . . . . . . . . . 15
Ylonen, et. al. Expires January 18, 2002 [Page 2]
Internet-Draft SSH Protocol Architecture July 2001
1. Introduction
SSH is a protocol for secure remote login and other secure network
services over an insecure network. It consists of three major
components:
o The Transport Layer Protocol [SSH-TRANS] provides server
authentication, confidentiality, and integrity. It may
optionally also provide compression. The transport layer will
typically be run over a TCP/IP connection, but might also be
used on top of any other reliable data stream.
o The User Authentication Protocol [SSH-USERAUTH] authenticates
the client-side user to the server. It runs over the transport
layer protocol.
o The Connection Protocol [SSH-CONNECT] multiplexes the encrypted
tunnel into several logical channels. It runs over the user
authentication protocol.
The client sends a service request once a secure transport layer
connection has been established. A second service request is sent
after user authentication is complete. This allows new protocols
to be defined and coexist with the protocols listed above.
The connection protocol provides channels that can be used for a
wide range of purposes. Standard methods are provided for setting
up secure interactive shell sessions and for forwarding
("tunneling") arbitrary TCP/IP ports and X11 connections.
2. Specification of Requirements
All documents related to the SSH protocols shall use the keywords
"MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
"SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" to describe
requirements. They are to be interpreted as described in [RFC-
2119].
3. Architecture
3.1 Host Keys
Each server host SHOULD have a host key. Hosts MAY have multiple
host keys using multiple different algorithms. Multiple hosts MAY
share the same host key. If a host has keys at all, it MUST have
at least one key using each REQUIRED public key algorithm
(currently DSS [FIPS-186]).
The server host key is used during key exchange to verify that the
client is really talking to the correct server. For this to be
possible, the client must have a priori knowledge of the server's
Ylonen, et. al. Expires January 18, 2002 [Page 3]
Internet-Draft SSH Protocol Architecture July 2001
public host key.
Two different trust models can be used:
o The client has a local database that associates each host name
(as typed by the user) with the corresponding public host key.
This method requires no centrally administered infrastructure,
and no third-party coordination. The downside is that the
database of name-to-key associations may become burdensome to
maintain.
o The host name-to-key association is certified by some trusted
certification authority. The client only knows the CA root
key, and can verify the validity of all host keys certified by
accepted CAs.
The second alternative eases the maintenance problem, since
ideally only a single CA key needs to be securely stored on the
client. On the other hand, each host key must be appropriately
certified by a central authority before authorization is
possible. Also, a lot of trust is placed on the central
infrastructure.
The protocol provides the option that the server name - host key
association is not checked when connecting to the host for the
first time. This allows communication without prior communication
of host keys or certification. The connection still provides
protection against passive listening; however, it becomes
vulnerable to active man-in-the-middle attacks. Implementations
SHOULD NOT normally allow such connections by default, as they
pose a potential security problem. However, as there is no widely
deployed key infrastructure available on the Internet yet, this
option makes the protocol much more usable during the transition
time until such an infrastructure emerges, while still providing a
much higher level of security than that offered by older solutions
(e.g. telnet [RFC-854] and rlogin [RFC-1282]).
Implementations SHOULD try to make the best effort to check host
keys. An example of a possible strategy is to only accept a host
key without checking the first time a host is connected, save the
key in a local database, and compare against that key on all
future connections to that host.
Implementations MAY provide additional methods for verifying the
correctness of host keys, e.g. a hexadecimal fingerprint derived
from the SHA-1 hash of the public key. Such fingerprints can
easily be verified by using telephone or other external
communication channels.
All implementations SHOULD provide an option to not accept host
Ylonen, et. al. Expires January 18, 2002 [Page 4]
Internet-Draft SSH Protocol Architecture July 2001
keys that cannot be verified.
We believe that ease of use is critical to end-user acceptance of
security solutions, and no improvement in security is gained if
the new solutions are not used. Thus, providing the option not to
check the server host key is believed to improve the overall
security of the Internet, even though it reduces the security of
the protocol in configurations where it is allowed.
3.2 Extensibility
We believe that the protocol will evolve over time, and some
organizations will want to use their own encryption,
authentication and/or key exchange methods. Central registration
of all extensions is cumbersome, especially for experimental or
classified features. On the other hand, having no central
registration leads to conflicts in method identifiers, making
interoperability difficult.
We have chosen to identify algorithms, methods, formats, and
extension protocols with textual names that are of a specific
format. DNS names are used to create local namespaces where
experimental or classified extensions can be defined without fear
of conflicts with other implementations.
One design goal has been to keep the base protocol as simple as
possible, and to require as few algorithms as possible. However,
all implementations MUST support a minimal set of algorithms to
ensure interoperability (this does not imply that the local policy
on all hosts would necessary allow these algorithms). The
mandatory algorithms are specified in the relevant protocol
documents.
Additional algorithms, methods, formats, and extension protocols
can be defined in separate drafts. See Section Algorithm Naming
(Section 5) for more information.
3.3 Policy Issues
The protocol allows full negotiation of encryption, integrity, key
exchange, compression, and public key algorithms and formats.
Encryption, integrity, public key, and compression algorithms can
be different for each direction.
The following policy issues SHOULD be addressed in the
configuration mechanisms of each implementation:
o Encryption, integrity, and compression algorithms, separately
for each direction. The policy MUST specify which is the
Ylonen, et. al. Expires January 18, 2002 [Page 5]
Internet-Draft SSH Protocol Architecture July 2001
preferred algorithm (e.g. the first algorithm listed in each
category).
o Public key algorithms and key exchange method to be used for
host authentication. The existence of trusted host keys for
different public key algorithms also affects this choice.
o The authentication methods that are to be required by the
server for each user. The server's policy MAY require multiple
authentication for some or all users. The required algorithms
MAY depend on the location where the user is trying to log in
from.
o The operations that the user is allowed to perform using the
connection protocol. Some issues are related to security; for
example, the policy SHOULD NOT allow the server to start
sessions or run commands on the client machine, and MUST NOT
allow connections to the authentication agent unless forwarding
such connections has been requested. Other issues, such as
which TCP/IP ports can be forwarded and by whom, are clearly
issues of local policy. Many of these issues may involve
traversing or bypassing firewalls, and are interrelated with
the local security policy.
3.4 Security Properties
The primary goal of the SSH protocol is improved security on the
Internet. It attempts to do this in a way that is easy to deploy,
even at the cost of absolute security.
o All encryption, integrity, and public key algorithms used are
well-known, well-established algorithms.
o All algorithms are used with cryptographically sound key sizes
that are believed to provide protection against even the
strongest cryptanalytic attacks for decades.
o All algorithms are negotiated, and in case some algorithm is
broken, it is easy to switch to some other algorithm without
modifying the base protocol.
Specific concessions were made to make wide-spread fast deployment
easier. The particular case where this comes up is verifying that
the server host key really belongs to the desired host; the
protocol allows the verification to be left out (but this is NOT
RECOMMENDED). This is believed to significantly improve usability
in the short term, until widespread Internet public key
infrastructures emerge.
3.5 Packet Size and Overhead
Some readers will worry about the increase in packet size due to
new headers, padding, and MAC. The minimum packet size is in the
order of 28 bytes (depending on negotiated algorithms). The
Ylonen, et. al. Expires January 18, 2002 [Page 6]
Internet-Draft SSH Protocol Architecture July 2001
increase is negligible for large packets, but very significant for
one-byte packets (telnet-type sessions). There are, however,
several factors that make this a non-issue in almost all cases:
o The minimum size of a TCP/IP header is 32 bytes. Thus, the
increase is actually from 33 to 51 bytes (roughly).
o The minimum size of the data field of an Ethernet packet is 46
bytes [RFC-894]. Thus, the increase is no more than 5 bytes.
When Ethernet headers are considered, the increase is less than
10 percent.
o The total fraction of telnet-type data in the Internet is
negligible, even with increased packet sizes.
The only environment where the packet size increase is likely to
have a significant effect is PPP [RFC-1134] over slow modem lines
(PPP compresses the TCP/IP headers, emphasizing the increase in
packet size). However, with modern modems, the time needed to
transfer is in the order of 2 milliseconds, which is a lot faster
than people can type.
There are also issues related to the maximum packet size. To
minimize delays in screen updates, one does not want excessively
large packets for interactive sessions. The maximum packet size
is negotiated separately for each channel.
3.6 Localization and Character Set Support
For the most part, the SSH protocols do not directly pass text
that would be displayed to the user. However, there are some
places where such data might be passed. When applicable, the
character set for the data MUST be explicitly specified. In most
places, ISO 10646 with UTF-8 encoding is used [RFC-2279]. When
applicable, a field is also provided for a language tag [RFC-
1766].
One big issue is the character set of the interactive session.
There is no clear solution, as different applications may display
data in different formats. Different types of terminal emulation
may also be employed in the client, and the character set to be
used is effectively determined by the terminal emulation. Thus,
no place is provided for directly specifying the character set or
encoding for terminal session data. However, the terminal
emulation type (e.g. "vt100") is transmitted to the remote site,
and it implicitly specifies the character set and encoding.
Applications typically use the terminal type to determine what
character set they use, or the character set is determined using
some external means. The terminal emulation may also allow
configuring the default character set. In any case, the character
set for the terminal session is considered primarily a client
Ylonen, et. al. Expires January 18, 2002 [Page 7]
Internet-Draft SSH Protocol Architecture July 2001
local issue.
Internal names used to identify algorithms or protocols are
normally never displayed to users, and must be in US-ASCII.
The client and server user names are inherently constrained by
what the server is prepared to accept. They might, however,
occasionally be displayed in logs, reports, etc. They MUST be
encoded using ISO 10646 UTF-8, but other encodings may be required
in some cases. It is up to the server to decide how to map user
names to accepted user names. Straight bit-wise binary comparison
is RECOMMENDED.
For localization purposes, the protocol attempts to minimize the
number of textual messages transmitted. When present, such
messages typically relate to errors, debugging information, or
some externally configured data. For data that is normally
displayed, it SHOULD be possible to fetch a localized message
instead of the transmitted message by using a numerical code. The
remaining messages SHOULD be configurable.
4. Data Type Representations Used in the SSH Protocols
byte
A byte represents an arbitrary 8-bit value (octet) [RFC-1700].
Fixed length data is sometimes represented as an array of
bytes, written byte[n], where n is the number of bytes in the
array.
boolean
A boolean value is stored as a single byte. The value 0
represents FALSE, and the value 1 represents TRUE. All non-
zero values MUST be interpreted as TRUE; however, applications
MUST NOT store values other than 0 and 1.
uint32
Represents a 32-bit unsigned integer. Stored as four bytes in
the order of decreasing significance (network byte order). For
example, the value 699921578 (0x29b7f4aa) is stored as 29 b7 f4
aa.
uint64
Represents a 64-bit unsigned integer. Stored as eight bytes in
the order of decreasing significance (network byte order).
string
Arbitrary length binary string. Strings are allowed to contain
arbitrary binary data, including null characters and 8-bit
Ylonen, et. al. Expires January 18, 2002 [Page 8]
Internet-Draft SSH Protocol Architecture July 2001
characters. They are stored as a uint32 containing its length
(number of bytes that follow) and zero (= empty string) or more
bytes that are the value of the string. Terminating null
characters are not used.
Strings are also used to store text. In that case, US-ASCII is
used for internal names, and ISO-10646 UTF-8 for text that
might be displayed to the user. The terminating null character
SHOULD NOT normally be stored in the string.
For example, the US-ASCII string "testing" is represented as 00
00 00 07 t e s t i n g. The UTF8 mapping does not alter the
encoding of US-ASCII characters.
mpint
Represents multiple precision integers in two's complement
format, stored as a string, 8 bits per byte, MSB first.
Negative numbers have the value 1 as the most significant bit
of the first byte of the data partition. If the most
significant bit would be set for a positive number, the number
MUST be preceded by a zero byte. Unnecessary leading bytes
with the value 0 or 255 MUST NOT be included. The value zero
MUST be stored as a string with zero bytes of data.
By convention, a number that is used in modular computations in
Z_n SHOULD be represented in the range 0 <= x < n.
Examples:
value (hex) representation (hex)
---------------------------------------------------------------
0 00 00 00 00
9a378f9b2e332a7 00 00 00 08 09 a3 78 f9 b2 e3 32 a7
80 00 00 00 02 00 80
-1234 00 00 00 02 ed cc
-deadbeef 00 00 00 05 ff 21 52 41 11
name-list
A string containing a comma separated list of names. A name
list is represented as a uint32 containing its length (number
of bytes that follow) followed by a comma-separated list of
zero or more names. A name MUST be non-zero length, and it
MUST NOT contain a comma (','). Context may impose additional
restrictions on the names; for example, the names in a list may
have to be valid algorithm identifier (see Algorithm Naming
below), or [RFC-1766] language tags. The order of the names in
Ylonen, et. al. Expires January 18, 2002 [Page 9]
Internet-Draft SSH Protocol Architecture July 2001
a list may or may not be significant, also depending on the
context where the list is is used. Terminating NUL characters
are not used, neither for the individual names, nor for the
list as a whole.
Examples:
value representation (hex)
---------------------------------------
(), the empty list 00 00 00 00
("zlib") 00 00 00 04 7a 6c 69 62
("zlib", "none") 00 00 00 09 7a 6c 69 62 2c 6e 6f 6e 65
5. Algorithm Naming
The SSH protocols refer to particular hash, encryption, integrity,
compression, and key exchange algorithms or protocols by names.
There are some standard algorithms that all implementations MUST
support. There are also algorithms that are defined in the
protocol specification but are OPTIONAL. Furthermore, it is
expected that some organizations will want to use their own
algorithms.
In this protocol, all algorithm identifiers MUST be printable US-
ASCII non-empty strings no longer than 64 characters. Names MUST
be case-sensitive.
There are two formats for algorithm names:
o Names that do not contain an at-sign (@) are reserved to be
assigned by IETF consensus (RFCs). Examples include `3des-
cbc', `sha-1', `hmac-sha1', and `zlib' (the quotes are not part
of the name). Names of this format MUST NOT be used without
first registering them. Registered names MUST NOT contain an
at-sign (@) or a comma (,).
o Anyone can define additional algorithms by using names in the
format name@domainname, e.g. "ourcipher-cbc@ssh.com". The
format of the part preceding the at sign is not specified; it
MUST consist of US-ASCII characters except at-sign and comma.
The part following the at-sign MUST be a valid fully qualified
internet domain name [RFC-1034] controlled by the person or
organization defining the name. It is up to each domain how it
manages its local namespace.
Ylonen, et. al. Expires January 18, 2002 [Page 10]
Internet-Draft SSH Protocol Architecture July 2001
6. Message Numbers
SSH packets have message numbers in the range 1 to 255. These
numbers have been allocated as follows:
Transport layer protocol:
1 to 19 Transport layer generic (e.g. disconnect, ignore, debug,
etc.)
20 to 29 Algorithm negotiation
30 to 49 Key exchange method specific (numbers can be reused for
different authentication methods)
User authentication protocol:
50 to 59 User authentication generic
60 to 79 User authentication method specific (numbers can be
reused for different authentication methods)
Connection protocol:
80 to 89 Connection protocol generic
90 to 127 Channel related messages
Reserved for client protocols:
128 to 191 Reserved
Local extensions:
192 to 255 Local extensions
7. IANA Considerations
Allocation of the following types of names in the SSH protocols is
assigned by IETF consensus:
o encryption algorithm names,
o MAC algorithm names,
o public key algorithm names (public key algorithm also implies
encoding and signature/encryption capability),
o key exchange method names, and
o protocol (service) names.
These names MUST be printable US-ASCII strings, and MUST NOT
contain the characters at-sign ('@'), comma (','), or whitespace
Ylonen, et. al. Expires January 18, 2002 [Page 11]
Internet-Draft SSH Protocol Architecture July 2001
or control characters (ASCII codes 32 or less). Names are case-
sensitive, and MUST NOT be longer than 64 characters.
Names with the at-sign ('@') in them are allocated by the owner of
DNS name after the at-sign (hierarchical allocation in [RFC-
2343]), otherwise the same restrictions as above.
Each category of names listed above has a separate namespace.
However, using the same name in multiple categories SHOULD be
avoided to minimize confusion.
Message numbers (see Section Message Numbers (Section 6)) in the
range of 0..191 should be allocated via IETF consensus; message
numbers in the 192..255 range (the "Local extensions" set) are
reserved for private use.
8. Security Considerations
Special care should be taken to ensure that all of the random
numbers are of good quality. The random numbers SHOULD be
produced with safe mechanisms discussed in [RFC-1750].
When displaying text, such as error or debug messages to the user,
the client software SHOULD replace any control characters (except
tab, carriage return and newline) with safe sequences to avoid
attacks by sending terminal control characters.
Not using MAC or encryption SHOULD be avoided. The user
authentication protocol is subject to man-in-the-middle attacks if
the encryption is disabled. The SSH protocol does not protect
against message alteration if no MAC is used.
9. Trademark Issues
As of this writing, SSH Communications Security Oy claims ssh as
its trademark. As with all IPR claims the IETF takes no position
regarding the validity or scope of this trademark claim.
10. Additional Information
The current document editor is: Darren.Moffat@Sun.COM. Comments
on this internet draft should be sent to the IETF SECSH working
group, details at: http://ietf.org/html.charters/secsh-
charter.html
References
[FIPS-186] Federal Information Processing Standards
Ylonen, et. al. Expires January 18, 2002 [Page 12]
Internet-Draft SSH Protocol Architecture July 2001
Publication, ., "FIPS PUB 186, Digital Signature
Standard", May 1994.
[RFC0854] Postel, J. and J. Reynolds, "Telnet Protocol
Specification", STD 8, RFC 854, May 1983.
[RFC0894] Hornig, C., "Standard for the transmission of IP
datagrams over Ethernet networks", STD 41, RFC
894, Apr 1984.
[RFC1034] Mockapetris, P., "Domain names - concepts and
facilities", STD 13, RFC 1034, Nov 1987.
[RFC1134] Perkins, D., "Point-to-Point Protocol: A proposal
for multi-protocol transmission of datagrams over
Point-to-Point links", RFC 1134, Nov 1989.
[RFC1282] Kantor, B., "BSD Rlogin", RFC 1282, December 1991.
[RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers",
STD 2, RFC 1700, October 1994.
[RFC1750] Eastlake, D., Crocker, S. and J. Schiller,
"Randomness Recommendations for Security", RFC
1750, December 1994.
[RFC1766] Alvestrand, H., "Tags for the Identification of
Languages", RFC 1766, March 1995.
[RFC2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14, RFC 2119,
March 1997.
[RFC2279] Yergeau, F., "UTF-8, a transformation format of
ISO 10646", RFC 2279, January 1998.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for
Writing an IANA Considerations Section in RFCs",
BCP 26, RFC 2434, October 1998.
[SSH-ARCH] Ylonen, T., "SSH Protocol Architecture", I-D
draft-ietf-architecture-09.txt, July 2001.
[SSH-TRANS] Ylonen, T., "SSH Transport Layer Protocol", I-D
draft-ietf-transport-11.txt, July 2001.
[SSH-USERAUTH] Ylonen, T., "SSH Authentication Protocol", I-D
draft-ietf-userauth-11.txt, July 2001.
Ylonen, et. al. Expires January 18, 2002 [Page 13]
Internet-Draft SSH Protocol Architecture July 2001
[SSH-CONNECT] Ylonen, T., "SSH Connection Protocol", I-D draft-
ietf-connect-11.txt, July 2001.
Authors' Addresses
Tatu Ylonen
SSH Communications Security Corp
Fredrikinkatu 42
HELSINKI FIN-00100
Finland
EMail: ylo@ssh.com
Tero Kivinen
SSH Communications Security Corp
Fredrikinkatu 42
HELSINKI FIN-00100
Finland
EMail: kivinen@ssh.com
Markku-Juhani O. Saarinen
University of Jyvaskyla
Timo J. Rinne
SSH Communications Security Corp
Fredrikinkatu 42
HELSINKI FIN-00100
Finland
EMail: tri@ssh.com
Sami Lehtinen
SSH Communications Security Corp
Fredrikinkatu 42
HELSINKI FIN-00100
Finland
EMail: sjl@ssh.com
Ylonen, et. al. Expires January 18, 2002 [Page 14]
Internet-Draft SSH Protocol Architecture July 2001
Full Copyright Statement
Copyright (C) The Internet Society (2001). 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.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Ylonen, et. al. Expires January 18, 2002 [Page 15]
