Network Working Group E. Lear
Internet-Draft K. Crozier
Expires: May 16, 2005 Cisco Systems
November 15, 2004
Using the NETCONF Protocol over Blocks Extensible Exchange Protocol
(BEEP)
draft-ietf-netconf-beep-03
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Abstract
This document specifies an application protocol mapping for the
NETCONF protocol over the Blocks Extensible Exchange Protocol (BEEP).
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Why BEEP? . . . . . . . . . . . . . . . . . . . . . . . . 3
2. BEEP Transport Mapping . . . . . . . . . . . . . . . . . . . . 4
2.1 NETCONF Session Establishment . . . . . . . . . . . . . . 4
2.2 Capabilities Exchange . . . . . . . . . . . . . . . . . . 4
2.3 NETCONF Session Usage . . . . . . . . . . . . . . . . . . 4
2.4 NETCONF Session Teardown . . . . . . . . . . . . . . . . . 5
2.5 BEEP Profile for NETCONF . . . . . . . . . . . . . . . . . 5
2.5.1 BEEP Profile . . . . . . . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 8
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.1 Normative References . . . . . . . . . . . . . . . . . . . . 11
6.2 Informative References . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12
A. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . 14
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1. Introduction
The NETCONF protocol [1] defines a simple mechanism through which a
network device can be managed. NETCONF is designed to be usable over
a variety of application protocols. This document specifies an
application protocol mapping for NETCONF over the Blocks Extensible
Exchange Protocol (BEEP) [2] .
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [4].
1.1 Why BEEP?
Use of BEEP is natural as an application protocol for transport of
XML. As a peer to peer protocol, BEEP provides an easy way to
implement NETCONF, no matter which side of the connection was the
initiator. This "bidirectionality" allows for either side to play
the role of the manager with no protocol changes. Either side can
open a channel. Either side could initiate an RPC. This is
particularly important to support operational models that involve
small devices connecting to a manager, and those devices that must
reverse the management connection in the face of firewalls and NATs.
The SASL profile used by BEEP allows for a simple and direct mapping
to the existing security model for CLI, while TLS provides a strong
well tested encryption mechanism with either server or server and
client-side authentication.
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2. BEEP Transport Mapping
All NETCONF over BEEP implementations MUST implement the profile and
functional mapping between NETCONF and BEEP as described below.
2.1 NETCONF Session Establishment
Managers may be either BEEP listeners or initiators. Similarly,
agents may be either listeners or initiators. Thus the initial
exchange takes place without regard to whether a manager or the agent
is the initiator. After the transport connection is established, as
greetings are exchanged, they should each announce their support for
TLS [6] and optionally SASL [5] (see below), as well as for the
SYSLOG profile [7]. Once greetings are exchanged, if TLS is to be
used and available by both parties, the listener STARTs a channel
with the TLS profile.
Once TLS has been started, a new greeting is sent by both initiator
and listener, as required by the BEEP RFC.
At this point, if SASL is desired, the initiator starts BEEP channel
1 to perform a SASL exchange to authenticate itself. When SASL is
completed, the channel MUST be closed.
Once authentication has occurred, there is no need to distinguish
between initiator and listener. We now distinguish between manager
and agent.
2.2 Capabilities Exchange
The manager now establishes an NETCONF a new channel. As initiators
assign odd channels and listeners assign even channels, this next
channel is BEEP channel 1 or 2, depending on whether the manager is
the initiator or the listener.
Certain NETCONF capabilities may require additional BEEP channels.
When such capabilities are defined, a BEEP mapping must be defined as
well.
At this point, the NETCONF session is established, and capabilities
have been exchanged.
2.3 NETCONF Session Usage
Nearly all NETCONF operations are executed through the <RPC> tag. To
issue an RPC, the manager transmits on the operational channel a BEEP
MSG containing the RPC and its arguments. In accordance with the
BEEP standard, RPC requests may be split across multiple BEEP frames.
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Once received and processed, the agent responds with BEEP RPYs on the
same channel with the response to the RPC. In accordance with the
BEEP standard, responses may be
split across multiple BEEP frames.
2.4 NETCONF Session Teardown
Upon receipt of <close-session> from the manager, once the agent has
completed all RPCs, it will close BEEP channel 0. When an agent
needs to initiate a close it will do so by closing BEEP channel 0.
Although not required to do so, the agent should allow for a
reasonable period for a manager to release an existing lock prior to
initiating a close. Once the agent has closed channel 0, all locks
are released, and each side follows tear down procedures as specified
in [3]. Having received a BEEP close or having sent <close-session>,
a manager MUST NOT send further requests. If there are additional
activities due to expanded capabilities, these MUST cease in an
orderly manner, and should be properly described in the capability
mapping.
2.5 BEEP Profile for NETCONF
There are two commands in the BEEP profile. <rpc> and <rpc-reply>.
2.5.1 BEEP Profile
<!-- DTD for netconf operations over BEEP
Refer to this DTD as:
<!ENTITY % NETCONF PUBLIC "netconf/Operation/1.0" "">
%NETCONF;
-->
<!-- Contents
Overview
Includes
Profile Summaries
Entity Definitions
Operations
rpc
rpc-reply
-->
<!-- Overview NETCONF operation channel -->
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<!-- Includes -->
<!ENTITY % BEEP PUBLIC "-//Blocks//DTD BEEP//EN"
"">
%BEEP;
<!-- Profile summaries
BEEP profile NETCONF
role MSG RPY ERR
==== === === ===
I or L rpc ok error
I or L rpc-reply ok error
-->
<!--
Entity Definitions
entity syntax/reference example
====== ================ =======
a RPC
RPC-DATA Alpha
a RPC reply number
RPC-REPLY 1*3DIGIT
-->
<!ENTITY % RPC-REPLY "CDATA">
<!ENTITY % RPC-DATA "CDATA">
-->
<!--
RPC command
-->
<!ELEMENT RPC (#PCDATA)>
<!ATTLIST RPC
RPC-DATA %RPC_DATA; #REQUIRED>
<!--
Result of RPC.
-->
<!ELEMENT RPC-REPLY (#PCDATA)>
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<!ATTLIST RPC-REPLY
RPC-REPLY %RPC-REPLY; #REQUIRED
RPC-DATA %RPC-DATA #REQUIRED>
<!-- End of DTD -->
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3. Security Considerations
Configuration information is by its very nature sensitive. Its
transmission in the clear and without integrity checking leaves
devices open to classic so-called "person in the middle" attacks.
Configuration information often times contains passwords, user names,
service descriptions, and topological information, all of which are
sensitive. A NETCONF application protocol, therefore, must minimally
support options for both confidentiality and authentication.
BEEP makes use of both transport layer security and SASL. We require
that TLS be used in BEEP as described by the BEEP standard.
Client-side certificates are strongly desirable, but an SASL
authentication is the bare minimum. SASL allows for the use of
protocols such as RADIUS [10], so that authentication can occur off
the box.
SASL authentication will occur on the first channel creation, and
prior to issuance of any protocol operations. No further
authentication may occur during the same session. This avoids a
situation where rights are different between different channels. If
an implementation wishes to support multiple accesses by different
individuals with different rights, then multiple sessions are
required.
Different environments may well allow different rights prior to and
then after authentication. An authorization model is not specified
in this document. When an operation is not properly authorized then
a simple "permission denied" is sufficient. Note that authorization
information may be exchanged in the form of configuration
information, which is all the more reason to ensure the security of
the connection.
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4. IANA Considerations
The IANA will assign a TCP port for NETCONF.
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5. Acknowledgments
This work is the product of the NETCONF IETF working group, and many
people have contributed to the NETCONF discussion. Most notably, Rob
Ens, Phil Schafer, Andy Bierman, Wes Hardiger, Ted Goddard, and
Margaret Wasserman all contributed in some fashion to this work,
which was originally to be found in the NETCONF base protocol
specification. Thanks also to Weijing Chen, Keith Allen, Juergen
Schoenwaelder, and Eamon O'Tuathail for their very constructive
participation.
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6. References
6.1 Normative References
[1] Enns, R., "NETCONF Configuration Protocol",
draft-ietf-netconf-prot-03 (work in progress), June 2004.
[2] Rose, M., "The Blocks Extensible Exchange Protocol Core", RFC
3080, March 2001.
[3] Rose, M., "Mapping the BEEP Core onto TCP", RFC 3081, March
2001.
[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[5] Myers, J., "Simple Authentication and Security Layer (SASL)",
RFC 2222, October 1997.
[6] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and
P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January
1999.
[7] New, D. and M. Rose, "Reliable Delivery for syslog", RFC 3195,
November 2001.
6.2 Informative References
[8] Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
"Extensible Markup Language (XML) 1.0 (Second Edition)", W3C
REC REC-xml-20001006, October 2000.
[9] Hollenbeck, S., Rose, M. and L. Masinter, "Guidelines for the
Use of Extensible Markup Language (XML) within IETF Protocols",
BCP 70, RFC 3470, January 2003.
[10] Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote
Authentication Dial In User Service (RADIUS)", RFC 2865, June
2000.
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Authors' Addresses
Eliot Lear
Cisco Systems
Glatt-com
Glattzentr
um, Zurich 8301
CH
EMail: lear@cisco.com
Ken Crozier
Cisco Systems
170 W. Tasman Dr.
San Jose, CA 95134-1706
US
EMail: kcrozier@cisco.com
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Appendix A. Change Log
03, 04: minor gnits relating to <close-session>
02: added comments about locking
01: Removed management channel, rpc-status, rpc-abort, and associated
profile changes.
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