--- 1/draft-ietf-netconf-server-model-01.txt 2014-09-16 17:14:42.000738496 -0700 +++ 2/draft-ietf-netconf-server-model-02.txt 2014-09-16 17:14:42.048739665 -0700 @@ -1,19 +1,19 @@ NETCONF Working Group K. Watsen Internet-Draft Juniper Networks Intended status: Standards Track J. Schoenwaelder -Expires: December 03, 2014 Jacobs University Bremen - June 2014 +Expires: March 20, 2015 Jacobs University Bremen + September 16, 2014 NETCONF Server Configuration Model - draft-ietf-netconf-server-model-01 + draft-ietf-netconf-server-model-02 Abstract This draft defines a NETCONF server configuration data model. This data model enables configuration of the NETCONF service itself, including which transports it supports, what ports they listen on, whether they support device-initiated connections, and associated parameters. Status of This Memo @@ -24,78 +24,74 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." - This Internet-Draft will expire on December 03, 2014. + This Internet-Draft will expire on March 20, 2015. Copyright Notice Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 3 2. Objectives . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Support all NETCONF Transports . . . . . . . . . . . . . 3 - 2.2. Align Transport-Specific Configurations . . . . . . . . . 4 + 2.2. Align Transport-Specific Configurations . . . . . . . . . 3 2.3. Support both Listening for Connections and Call Home . . 4 2.4. For Call Home Connections . . . . . . . . . . . . . . . . 4 2.4.1. Support More than One Application . . . . . . . . . . 4 2.4.2. Support Applications Having More than One Server . . 4 2.4.3. Support a Reconnection Strategy . . . . . . . . . . . 4 2.4.4. Support both Persistent and Periodic Connections . . 5 2.4.5. Reconnection Strategy for Periodic Connections . . . 5 2.4.6. Keep-Alives for Persistent Connections . . . . . . . 5 2.4.7. Customizations for Periodic Connections . . . . . . . 5 3. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 6 - 3.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 7 - 4. Keep-Alives for SSH and TLS . . . . . . . . . . . . . . . . . 16 - 4.1. SSH . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 - 4.2. TLS . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 - 5. User Authentication for TLS . . . . . . . . . . . . . . . . . 17 - 5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 17 - 5.2. Data Model Overview . . . . . . . . . . . . . . . . . . . 17 - 5.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 18 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 23 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 - 8. Other Considerations . . . . . . . . . . . . . . . . . . . . 24 - 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24 - 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 - 10.1. Normative References . . . . . . . . . . . . . . . . . . 24 - 10.2. Informative References . . . . . . . . . . . . . . . . . 26 - Appendix A. Example: SSH Transport Configuration . . . . . . . . 26 - Appendix B. Example: TLS Transport Configuration . . . . . . . . 27 - Appendix C. Example: TLS Authentication Configuration . . . . . 28 - Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 29 - D.1. I-D to 00 . . . . . . . . . . . . . . . . . . . . . . . . 29 - D.2. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 29 - Appendix E. Open Issues . . . . . . . . . . . . . . . . . . . . 29 + 3.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 8 + 4. Keep-Alives for SSH and TLS . . . . . . . . . . . . . . . . . 21 + 4.1. SSH . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 + 4.2. TLS . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 + 5. Security Considerations . . . . . . . . . . . . . . . . . . . 22 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 + 7. Other Considerations . . . . . . . . . . . . . . . . . . . . 23 + 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 23 + 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 + 9.1. Normative References . . . . . . . . . . . . . . . . . . 24 + 9.2. Informative References . . . . . . . . . . . . . . . . . 25 + Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 26 + A.1. SSH Transport Configuration . . . . . . . . . . . . . . . 26 + A.2. TLS Transport Configuration . . . . . . . . . . . . . . . 26 + Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 27 + B.1. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 28 + B.2. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 28 + Appendix C. Open Issues . . . . . . . . . . . . . . . . . . . . 28 1. Introduction This draft defines a NETCONF [RFC6241] server configuration data model. This data model enables configuration of the NETCONF service itself, including which transports are supported, what ports does the server listen on, whether call-home is supported, and associated parameters. 1.1. Terminology @@ -128,21 +124,21 @@ includes the following objectives: 2.1. Support all NETCONF Transports The YANG module should support all current NETCONF transports, namely NETCONF over SSH [RFC6242] and NETCONF over TLS [I-D.ietf-netconf-rfc5539bis], and be extensible to support future transports as necessary. Since implementations may not support all transports, the module - should use YANG "feature" statements so that implementation can + should use YANG "feature" statements so that implementations can accurately advertise which transports are supported. 2.2. Align Transport-Specific Configurations While each transport is unique in its protocol and may have some distinct configurations, there remains a significant overlap between them. Thus the YANG module should use "grouping" statements so that the common aspects can be configured similarly. 2.3. Support both Listening for Connections and Call Home @@ -237,52 +233,46 @@ will send another shortly thereafter. Likewise, the application may have a sequence of pending messages to send. Thus, it should be possible for a device to hold a connection open until some amount of time of no data being transmitted as transpired. 3. Data Model 3.1. Overview To enable transports to configure listening on one or more ports in a - common way, this grouping is defined. This grouping defines SSH and - TLS specific containers, each of which refines the default listening - port appropriately. Further, each of these transport specific - containers use a feature statement, enabling NETCONF servers to - accurately advertise what they support. + common way, the following subtree is defined. This subtree defines + SSH and TLS specific containers, each of which refines the default + listening port appropriately. Further, each of these transport + specific containers use a feature statement, enabling NETCONF servers + to accurately advertise what they support. module: ietf-netconf-server +--rw netconf-server - +--rw listen - +--rw ssh {ssh-listen}? - | +--rw (one-or-many)? - | +--:(one-port) - | | +--rw port? inet:port-number - | +--:(many-ports) - | +--rw interface* [address] + +--rw listen* [name] + +--rw name string + +--rw (transport) + +--:(ssh) {ssh-listen}? + | +--rw ssh | +--rw address inet:host | +--rw port? inet:port-number - +--rw tls {tls-listen}? - +--rw (one-or-many)? - +--:(one-port) - | +--rw port? inet:port-number - +--:(many-ports) - +--rw interface* [address] + +--:(tls) {tls-listen}? + +--rw tls +--rw address inet:host +--rw port? inet:port-number To enable transports to configure initiating connections to remote - applications in a common way, this grouping is defined. This - grouping configures a list of network-managers, each with some - transport-specific configuration augmented in. Each of the transport - specific containers use a feature statement, enabling NETCONF servers - to accurately advertise what they support. + applications in a common way, the following subtree is defined. This + subtree configures a list of appliacations, each with some transport- + specific configuration augmented in. Each of the transport specific + containers use a feature statement, enabling NETCONF servers to + accurately advertise what they support. module: ietf-netconf-server +--rw netconf-server +--rw call-home +--rw network-managers +--rw network-manager* [name] +--rw name string +--rw description? string +--rw endpoints | +--rw endpoint* [address] @@ -303,37 +293,75 @@ | | +--rw count-max? uint8 | +--:(periodic-connection) | +--rw periodic | +--rw timeout-mins? uint8 | +--rw linger-secs? uint8 +--rw reconnect-strategy +--rw start-with? enumeration +--rw interval-secs? uint8 +--rw count-max? uint8 + The following subtree illustrates how this YANG module enables + authentication of TLS client certificates and mapping TLS clients to + NETCONF user names. More specifically, the "trusted-ca-certs" and + "trusted-client-certs" containers are used to authenticate TLS client + certificates, while "cert-maps" and "psk-maps" are used to map TLS + clients to NETCONF user names. + + module: ietf-netconf-server + +--rw netconf-server + +--rw tls-client-auth + +--rw trusted-ca-certs + | +--rw trusted-ca-cert* binary + +--rw trusted-client-certs + | +--rw trusted-client-cert* binary + +--rw cert-maps {tls-map-certificates}? + | +--rw cert-to-name* [id] + | +--rw id uint32 + | +--rw fingerprint x509c2n:tls-fingerprint + | +--rw map-type identityref + | +--rw name string + +--rw psk-maps {tls-map-pre-shared-keys}? + +--rw psk-map* [psk-identity] + +--rw psk-identity string + +--rw user-name nacm:user-name-type + +--rw not-valid-before? yang:date-and-time + +--rw not-valid-after? yang:date-and-time + +--rw key yang:hex-string + 3.2. YANG Module - This YANG module imports YANG types from [RFC6991]. + This YANG module imports YANG types from [RFC6991], [RFC6536], and + [draft-ietf-netmod-snmp-cfg]. RFC Ed.: update the date below with the date of RFC publication and remove this note. - file "ietf-netconf-server.@2014-05-16.yang" + file "ietf-netconf-server@YYYY-MM-DD.yang" module ietf-netconf-server { namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-server"; prefix "ncserver"; import ietf-inet-types { prefix inet; // RFC 6991 } + import ietf-yang-types { + prefix yang; // RFC 6991 + } + import ietf-netconf-acm { + prefix nacm; // RFC 6536 + } + import ietf-x509-cert-to-name { + prefix x509c2n; // draft-ietf-netmod-snmp-cfg + } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: WG List: WG Chair: Mehmet Ersue @@ -357,185 +385,293 @@ Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; // RFC Ed.: replace XXXX with actual RFC number and // remove this note // RFC Ed.: please update the date to the date of publication - revision "2014-01-24" { + revision "YYYY-MM-DD" { description "Initial version"; reference "RFC XXXX: NETCONF Server Configuration Model"; } // Features - - feature ssh { - description - "A NETCONF server implements this feature if it supports NETCONF - over Secure Shell (SSH)."; - reference - "RFC 6242: Using the NETCONF Protocol over Secure Shell (SSH)"; - } - feature ssh-listen { description "The ssh-listen feature indicates that the NETCONF server can open a port to listen for incoming client connections."; } feature ssh-call-home { description "The ssh-call-home feature indicates that the NETCONF server can connect to a client."; reference "RFC XXXX: Reverse Secure Shell (Reverse SSH)"; } - feature tls { - description - "A NETCONF server implements this feature if it supports NETCONF - over Transport Layer Security (TLS)."; - reference - "RFC XXXX: NETCONF over Transport Layer Security (TLS)"; - } - feature tls-listen { description "The tls-listen feature indicates that the NETCONF server can open a port to listen for incoming client connections."; } feature tls-call-home { description "The tls-call-home feature indicates that the NETCONF server can connect to a client."; } + feature tls-map-certificates { + description + "The tls-map-certificates feature indicates that the + NETCONF server implements mapping X.509 certificates to NETCONF + usernames."; + } + + feature tls-map-pre-shared-keys { + description + "The tls-map-pre-shared-keys feature indicates that the + NETCONF server implements mapping TLS pre-shared keys + to NETCONF usernames."; + } + + // Module's top-level container + container netconf-server { + description + "Top-level container for NETCONF server configuration."; + list listen { + key name; + description + "List of endpoints to listen for connections on."; + //if-feature "(ssh-listen or tls-listen)"; + uses listen-config; + } + list call-home { + key name; + description + "List of applications to call-home to."; + //if-feature "(ssh-call-home or tls-call-home)"; + uses call-home-config; + } + container tls-client-auth { + //if-feature "(tls-listen or tls-call-home)"; + description + "Container for TLS client authentication configuration."; + uses trusted-ca-certs-grouping; + uses trusted-client-certs-grouping; + uses cert-maps-grouping; + uses psk-maps-grouping; + } + } + // Groupings - grouping one-or-many-config { + grouping listen-config { description - "Provides a choice of configuring one of more ports - to listen for incoming client connections."; + "Grouping for listen configuration."; + leaf name { + type string; + description + "An arbitrary name for the listen endpoint."; + } + choice transport { + mandatory true; + description + "Selects between SSH and TLS transports."; + case ssh { + if-feature ssh-listen; + container ssh { + description + "SSH-specific listening configuration for inbound + connections."; + uses listen-per-transport-config { + refine port { + default 830; - choice one-or-many { - default one-port; - case one-port { - leaf port { - type inet:port-number; + } + } + } + } + case tls { + if-feature tls-listen; + container tls { description - "The port number the NETCONF server listens on on all - interfaces."; + "TLS-specific listening configuration for inbound + connections."; + uses listen-per-transport-config { + refine port { + default 6513; + } + } + } + } } } - case many-ports { - list interface { - key "address"; + grouping listen-per-transport-config { + description + "Provides the configuration of the NETCONF server to + open one or more ports to listen for incoming client + connections."; leaf address { type inet:host; mandatory true; description - "The local IP address of the interface to listen - on."; + "The local IP address/name of the interface to listen on."; } leaf port { type inet:port-number; description "The local port number on this interface the NETCONF server listens on."; } } + + grouping call-home-config { + description + "Grouping for call-home configuration."; + leaf name { + type string; + description + "An arbitrary name for the remote application."; } - } + uses call-home-transport-config; + uses call-home-connection-type-config; + uses call-home-reconnection-strategy-config; } - grouping network-managers-config { - container network-managers { + grouping call-home-transport-config { description - "A list of network managers the device initates connections - to. The configuration for each network manager specifies - its details, including its endpoints, the type of - connection to maintain, and the reconnection strategy - to use."; - - list network-manager { + "Grouping for call-home specific transport selection."; + choice transport { + mandatory true; + description + "Selects between SSH and TLS transports."; + case ssh { + if-feature ssh-call-home; + container ssh { + description + "Specifies SSH-specific call-home transport + configuration."; + uses call-home-per-transport-config { + refine endpoints/endpoint/port { + default 9999; // pending IANA assignment + } + } + list host-key { key name; + min-elements 1; + ordered-by user; + description + "User-ordered list of host-keys the SSH server + should advertize."; leaf name { - type string { - length 1..64; // XXX why these limits? - } + type string; mandatory true; description - "An arbitrary name for the network manager the device - is connecting to."; + "The name of a host key the device should + advertise during the SSH key exchange."; } - leaf description { - type string; + } + } + } + case tls { + if-feature tls-call-home; + container tls { description - "An optional description for the network manager."; + "Specifies TLS-specific call-home transport + configuration."; + uses call-home-per-transport-config { + refine endpoints/endpoint/port { + default 9999; // pending IANA assignment + + } + } } + } + } + } + + grouping call-home-per-transport-config { + description + "Grouping for transport-specific configuration for + call-home connections."; container endpoints { description - "An ordered listing of the network manager's - endpoints that the device should attempt connecting - to. Defining more than one enables the device to - support high-availability scenarios."; + "Container for the list of endpoints."; list endpoint { - key address; + key name; min-elements 1; ordered-by user; + description + "User-ordered list of endpoints for this application. + Defining more than one enables high-availability."; + leaf name { + type string; + description + "An arbitrary name for the endpoint to connect to."; + } leaf address { type inet:host; mandatory true; description "The hostname or IP address of the endpoint. If a hostname is provided and DNS resolves to more than one IP address, the device SHOULD try all of the ones it can based on how its networking stack is configured (e.g. v4, v6, dual-stack)."; } leaf port { type inet:port-number; description "The IP port for this endpoint. The device will use the IANA-assigned well-known port if not specified."; } } } - container transport { } + grouping call-home-connection-type-config { + description + "Grouping to define connection-type for call-home + based connections."; container connection-type { description "Indicates the network manager's preference for how the device's connection is maintained."; choice connection-type { default persistent-connection; + description + "Selects between persistent and periodic connections."; case persistent-connection { container persistent { description "Maintain a persistent connection to the network manager. If the connection goes down, immediately start trying to reconnect to it, using the reconnection strategy. This connection type minimizes any manager-to-device data-transfer delay, albeit at the expense of holding resources longer."; container keep-alives { + description + "Configures keep-alive policy, to proactively + detect when a persistent connection to an + endpoint has dropped."; leaf interval-secs { type uint8; units seconds; default 15; description "Sets a timeout interval in seconds after which if no data has been received from the manager's endpoint, a message will be sent to request a response from the endpoint. A value of '0' indicates that no keep-alive messages should @@ -590,335 +725,82 @@ units seconds; default 30; description "The amount of time the device should wait after last receiving data from or sending data to the network manager's endpoint before closing its connection to it. This is an optimization to prevent unnecessary connections."; } } + + } } } } - // XXX - // Should we have something smarter as the reconnect - // strategy, e.g. an exponential backoff? - + grouping call-home-reconnection-strategy-config { + description + "Grouping for reconnection strategy."; container reconnect-strategy { description "The reconnection strategy guides how a device reconnects - to an network manager, after losing a connection to it, + to an application, after losing a connection to it, even if due to a reboot. The device starts with the specified endpoint, tries to connect to it count-max times, waiting interval-secs between each connection attempt, before trying the next endpoint in the list (round robin)."; leaf start-with { type enumeration { - enum first-listed { value 1; } - enum last-connected { value 2; } + enum first-listed { + description + "Indicates that reconnections should start with + the first endpoint listed."; + } + enum last-connected { + description + "Indicates that reconnections should start with + the endpoint last connected to."; + } } default first-listed; description - "Specifies which of the network manager's endpoints the + "Specifies which of the application's endpoints the device should start with when trying to connect to - the network manager. If no previous connection has - ever been established, last-connected defaults to the - first endpoint listed."; + the application. If no previous connection has + ever been established, last-connected defaults to + the first endpoint listed."; } leaf interval-secs { type uint8; units seconds; default 5; description "Specifies the time delay between connection attempts to the same endpoint. Note: this value differs from the periodic-connection's timeout-mins value."; } leaf count-max { type uint8; default 3; description "Specifies the number times the device tries to connect to a specific endpoint before moving on to the next endpoint in the list (round robin)."; } } } - } - } - - grouping listen-config { - description - "Provides the configuration of the NETCONF server to - open one or more ports to listen for incoming client - connections."; - container ssh { - if-feature ssh-listen; - uses one-or-many-config { - refine one-or-many/one-port/port { - default 830; - } - refine one-or-many/many-ports/interface/port { - default 830; - } - } - } - container tls { - if-feature tls-listen; - uses one-or-many-config { - refine one-or-many/one-port/port { - default 6513; - } - refine one-or-many/many-ports/interface/port { - default 6513; - } - } - } - } - - grouping call-home-config { - description - "Provides the configuration of the NETCONF call-home - clients to connect to, the overall call-home policy, - and the reconnect strategy."; - - uses network-managers-config { - augment network-managers/network-manager/transport { - container ssh { - if-feature ssh-call-home; - container host-keys { - description - "An ordered listing of the SSH host keys the - device should advertise to the network manager."; - list host-key { - key name; - min-elements 1; // requires 'ssh' element? - ordered-by user; - leaf name { - type string; - mandatory true; - description - "The name of a host key the device should - advertise during the SSH key exchange."; - } - } - } - } - container tls { - if-feature tls-call-home; - presence "Enables call home using TLS when configured."; - } - } - } - } - - // Module's top-level container - container netconf-server { - description - "Top-level container for NETCONF server configuration."; - container listen { - uses listen-config; - } - container call-home { - uses call-home-config; - } - } - - } - - - -4. Keep-Alives for SSH and TLS - - One the objectives listed above, Keep-Alives for Persistent - Connections (Section 2.4.6) indicates a need for a "keep-alive" - mechanism. This section specifies how the NETCONF keep-alive - mechanism is to be implemented. - - Both SSH and TLS have the ability to support keep-alives. Using - these mechanisms, the keep-alive messages are sent inside the - encrypted tunnel, thus thwarting spoof attacks. - -4.1. SSH - - The SSH keep-alive solution that is expected to be used when - configured using the data model defined in this document is - ubiquitous in practice, though never being explicitly defined in an - RFC. The strategy used is to purposely send a malformed request - message with a flag set to ensure a response. More specifically, per - section 4 of [RFC4253], either SSH peer can send a - SSH_MSG_GLOBAL_REQUEST message with "want reply" set to '1' and that, - if there is an error, will get back a SSH_MSG_REQUEST_FAILURE - response. Similarly, section 5 of [RFC4253] says that either SSH - peer can send a SSH_MSG_CHANNEL_REQUEST message with "want reply" set - to '1' and that, if there is an error, will get back a - SSH_MSG_CHANNEL_FAILURE response. - - To ensure that the request will fail, current implementations send an - invalid "request name" or "request type", respectively. Abiding to - the extensibility guidelines specified in Section 6 of [RFC4251], - these implementations use the "name@domain". For instance, when - configured to send keep-alives, OpenSSH sends the string - "keepalive@openssh.com". In order to remain compatible with existing - implementations, this draft does not require a specific "request - name" or "request type" string be used. - -4.2. TLS - - The TLS keep-alive solution is defined in [RFC6520]. This solution - allows both peers to advertise if they can receive heartbeat request - messages from its peer. For standard NETCONF over TLS connections, - devices SHOULD advertise "peer_allowed_to_send", as per [RFC6520]. - This advertisement is not a "MUST" in order to grandfather existing - NETCONF over TLS implementations. For NETCONF over TLS Call Home, - the network management system MUST advertise "peer_allowed_to_send" - per [RFC6520]. This is a "MUST" so as to ensure devices can depend - in it always being there for call home connections, which is - conveniently when keep-alives are needed the most. - -5. User Authentication for TLS - -5.1. Introduction - - The NETCONF Server Module defined in this draft focuses on the - configuration the SSH and TLS transports. This module does not - define a means to configure User Authentication, as that is a stated - focus for [draft-ietf-netmod-system-mgmt], however, that draft does - not define configuration nodes for TLS client authentication. Thus, - this draft also includes the following YANG module to augment TLS - client authentication into the "ietf-system" module defined in - [draft-ietf-netmod-system-mgmt]. - -5.2. Data Model Overview - - This data model augments the "ietf-system" module defined in - [draft-ietf-netmod-system-mgmt] by adding some configuration nodes - under its "/system/authentication" subtree. - - module: ietf-system-tls-auth - augment /sys:system/sys:authentication: - +--rw tls - +--rw trusted-ca-certs - | +--rw trusted-ca-cert* binary - +--rw trusted-client-certs - | +--rw trusted-client-cert* binary - +--rw cert-maps {tls-map-certificates}? - | +--rw cert-to-name* [id] - | +--rw id uint32 - | +--rw fingerprint x509c2n:tls-fingerprint - | +--rw map-type identityref - | +--rw name string - +--rw psk-maps {tls-map-pre-shared-keys}? - +--rw psk-map* [psk-identity] - +--rw psk-identity string - +--rw user-name nacm:user-name-type - +--rw not-valid-before? yang:date-and-time - +--rw not-valid-after? yang:date-and-time - +--rw key yang:hex-string - -5.3. YANG Module - - This YANG module imports YANG extensions from [RFC6536], and imports - YANG types from [RFC6991] and a YANG grouping from - [I-D.ietf-netmod-snmp-cfg]. - - RFC Ed.: update the date below with the date of RFC publication - and remove this note. - - file "ietf-system-tls-auth.@2014-05-16.yang" - - module ietf-system-tls-auth { - - namespace "urn:ietf:params:xml:ns:yang:ietf-system-tls-auth"; - prefix "system-tls-auth"; - - import ietf-system { // draft-ietf-netmod-system-mgmt - prefix "sys"; - } - import ietf-netconf-acm { - prefix nacm; // RFC 6536 - } - import ietf-yang-types { - prefix yang; // RFC 6991 - } - import ietf-x509-cert-to-name { - prefix x509c2n; // I-D.ietf-netconf-rfc5539bis - } - - organization - "IETF NETCONF (Network Configuration) Working Group"; - - contact - "WG Web: - WG List: - - WG Chair: Mehmet Ersue - - - WG Chair: Bert Wijnen - - Editor: Kent Watsen - - - Juergen Schoenwaelder - "; - - description - "This module augments the ietf-system module in order to - add TLS authentication configuration nodes to the - 'authentication' container. - - Copyright (c) 2014 IETF Trust and the persons identified as - authors of the code. All rights reserved. - - Redistribution and use in source and binary forms, with or - without modification, is permitted pursuant to, and subject - to the license terms contained in, the Simplified BSD - License set forth in Section 4.c of the IETF Trust's - Legal Provisions Relating to IETF Documents - (http://trustee.ietf.org/license-info). - - This version of this YANG module is part of RFC XXXX; see - the RFC itself for full legal notices."; - // RFC Ed.: replace XXXX with actual RFC number and - // remove this note - - // RFC Ed.: please update the date to the date of publication - - revision "2014-05-24" { - description - "Initial version"; - reference - "RFC XXXX: NETCONF Server Configuration Model"; - } - // Features - - feature tls-map-certificates { - description - "The tls-map-certificates feature indicates that the - NETCONF server implements mapping X.509 certificates to NETCONF - usernames."; - } - - feature tls-map-pre-shared-keys { + grouping trusted-ca-certs-grouping { description - "The tls-map-pre-shared-keys feature indicates that the - NETCONF server implements mapping TLS pre-shared keys to NETCONF - usernames."; - } - - grouping tls-global-config { - + "Grouping for trusted-ca-certs container."; container trusted-ca-certs { description "A list of Certificate Authority (CA) certificates that a NETCONF server can use to authenticate a NETCONF client's certificate. A client's certificate is authenticated if its Issuer matches one of the configured trusted CA certificates."; leaf-list trusted-ca-cert { type binary; ordered-by system; @@ -927,80 +809,94 @@ specified by RFC 5246, Section 7.4.6, i.e.,: opaque ASN.1Cert<1..2^24>; "; reference "RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2"; } } + } + grouping trusted-client-certs-grouping { + description + "Grouping for trusted-client-certs container."; container trusted-client-certs { description "A list of client certificates that a NETCONF server can use to authenticate a NETCONF client's certificate. A client's certificate is authenticated if it is an exact - match to one of the configured trusted client certificates."; + match to a configured trusted client certificates."; leaf-list trusted-client-cert { type binary; ordered-by system; description "The binary certificate structure, as specified by RFC 5246, Section 7.4.6, i.e.,: opaque ASN.1Cert<1..2^24>; "; reference "RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2"; } } + } // Objects for deriving NETCONF usernames from X.509 // certificates. + grouping cert-maps-grouping { + description + "Grouping for cert-maps container."; container cert-maps { if-feature tls-map-certificates; uses x509c2n:cert-to-name; description "The cert-maps container is used by a NETCONF server to map the NETCONF client's presented X.509 certificate to a NETCONF username. If no matching and valid cert-to-name list entry can be found, then the NETCONF server MUST close the connection, and MUST NOT accept NETCONF messages over it."; } + } // Objects for deriving NETCONF usernames from TLS // pre-shared keys. + grouping psk-maps-grouping { + description + "Grouping for psk-maps container."; container psk-maps { if-feature tls-map-pre-shared-keys; description "During the TLS Handshake, the client indicates which key to use by including a PSK identity in the TLS ClientKeyExchange message. On the NETCONF server side, this PSK identity is used to look up an entry in the psk-map list. If such an entry is found, and the pre-shared keys match, then the client is authenticated. The NETCONF server uses the value from the user-name leaf in the psk-map list as the NETCONF username. If the NETCONF server cannot find an entry in the psk-map list, or if the pre-shared keys do not match, then the NETCONF server terminates the connection."; reference "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)"; list psk-map { key psk-identity; + description + "List a pre-shared key mappings."; leaf psk-identity { type string; description "The PSK identity encoded as a UTF-8 string. For details how certain common PSK identity formats can be encoded in UTF-8, see section 5.1. of RFC 4279."; reference "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)"; @@ -1030,31 +926,74 @@ nacm:default-deny-all; description "The key associated with the PSK identity"; reference "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)"; } } } } - augment "/sys:system/sys:authentication" { - container tls { - uses tls-global-config; - } - } } -6. Security Considerations +4. Keep-Alives for SSH and TLS + + One the objectives listed above, Keep-Alives for Persistent + Connections (Section 2.4.6) indicates a need for a "keep-alive" + mechanism. This section specifies how the NETCONF keep-alive + mechanism is to be implemented. + + Both SSH and TLS have the ability to support keep-alives. Using + these mechanisms, the keep-alive messages are sent inside the + encrypted tunnel, thus thwarting spoof attacks. + +4.1. SSH + + The SSH keep-alive solution that is expected to be used when + configured using the data model defined in this document is + ubiquitous in practice, though never being explicitly defined in an + RFC. The strategy used is to purposely send a malformed request + message with a flag set to ensure a response. More specifically, per + section 4 of [RFC4253], either SSH peer can send a + SSH_MSG_GLOBAL_REQUEST message with "want reply" set to '1' and that, + if there is an error, will get back a SSH_MSG_REQUEST_FAILURE + response. Similarly, section 5 of [RFC4253] says that either SSH + peer can send a SSH_MSG_CHANNEL_REQUEST message with "want reply" set + to '1' and that, if there is an error, will get back a + SSH_MSG_CHANNEL_FAILURE response. + + To ensure that the request will fail, current implementations send an + invalid "request name" or "request type", respectively. Abiding to + the extensibility guidelines specified in Section 6 of [RFC4251], + these implementations use the "name@domain". For instance, when + configured to send keep-alives, OpenSSH sends the string + "keepalive@openssh.com". In order to remain compatible with existing + implementations, this draft does not require a specific "request + name" or "request type" string be used. + +4.2. TLS + + The TLS keep-alive solution is defined in [RFC6520]. This solution + allows both peers to advertise if they can receive heartbeat request + messages from its peer. For standard NETCONF over TLS connections, + devices SHOULD advertise "peer_allowed_to_send", as per [RFC6520]. + This advertisement is not a "MUST" in order to grandfather existing + NETCONF over TLS implementations. For NETCONF over TLS Call Home, + the network management system MUST advertise "peer_allowed_to_send" + per [RFC6520]. This is a "MUST" so as to ensure devices can depend + in it always being there for call home connections, which is + conveniently when keep-alives are needed the most. + +5. Security Considerations The YANG modules defined in this memo are designed to be accessed via the NETCONF protocol [RFC6241]. Authorization for access to specific portions of conceptual data and operations within this module is provided by the NETCONF access control model (NACM) [RFC6536]. There are a number of data nodes defined in the "ietf-netconf-server" and "ietf-system-tls-auth" YANG modules which are writable/creatable/ deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network @@ -1071,21 +1010,21 @@ o /system/authentication/tls/psk-maps/psk-map/user-name: This leaf node contains a user name that some deployments may consider sensitive information. o /system/authentication/tls/psk-maps/psk-map/key: This leaf node contains a shared key that remote clients use to authenticate themselves to the system. This value should not be readable or writable by anyone by default. -7. IANA Considerations +6. IANA Considerations This document registers two URIs in the IETF XML registry [RFC2119]. Following the format in [RFC3688], the following registrations are requested: URI: urn:ietf:params:xml:ns:yang:ietf-netconf-server Registrant Contact: The NETCONF WG of the IETF. XML: N/A, the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-system-tle-auth @@ -1098,219 +1037,164 @@ name: ietf-netconf-server namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-server prefix: ncserver reference: RFC XXXX name: ietf-system-tls-auth namespace: urn:ietf:params:xml:ns:yang:ietf-system-tls-auth prefix: sys-tls-auth reference: RFC XXXX -8. Other Considerations +7. Other Considerations The YANG module define herein does not itself support virtual routing and forwarding (VRF). It is expected that external modules will augment in VRF designations when needed. -9. Acknowledgements +8. Acknowledgements The authors would like to thank for following for lively discussions on list and in the halls (ordered by last name): Andy Bierman, Martin Bjorklund, Benoit Claise, David Lamparter, Alan Luchuk, Ladislav Lhotka, Radek Krejci, Tom Petch, and Phil Shafer. Juergen Schoenwaelder and was partly funded by Flamingo, a Network of Excellence project (ICT-318488) supported by the European Commission under its Seventh Framework Programme. -10. References +9. References -10.1. Normative References +9.1. Normative References + + [I-D.ietf-netconf-rfc5539bis] + Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the + NETCONF Protocol over Transport Layer Security (TLS)", + draft-ietf-netconf-rfc5539bis-04 (work in progress), + October 2013. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels ", BCP 14, RFC 2119, March 1997. [RFC4251] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) Protocol Architecture ", RFC 4251, January 2006. [RFC4253] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) Transport Layer Protocol ", RFC 4253, January 2006. [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF) ", RFC 6020, October 2010. + [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., + and A. Bierman, Ed., "NETCONF Configuration Protocol", RFC + 6241, June 2011. + + [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure + Shell (SSH)", RFC 6242, June 2011. + [RFC6520] Seggelmann, R., Tuexen, M., and M. Williams, "Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) Heartbeat Extension ", RFC 6520, February 2012. [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model ", RFC 6536, March 2012. [RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, July 2013. - [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., - and A. Bierman, Ed., "NETCONF Configuration Protocol", RFC - 6241, June 2011. - - [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure - Shell (SSH)", RFC 6242, June 2011. - - [I-D.ietf-netconf-rfc5539bis] - Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the - NETCONF Protocol over Transport Layer Security (TLS) ", - draft-ietf-netconf-rfc5539bis-04 (work in progress), - October 2013. + [draft-ieft-netconf-reverse-ssh] + Watsen, K., "NETCONF over SSH Call Home", draft-ieft- + netconf-reverse-ssh-00 (work in progress), May 2014. - [I-D.ietf-netmod-snmp-cfg] + [draft-ietf-netmod-snmp-cfg] Bjorklund, M. and J. Schoenwaelder, "A YANG Data Model for SNMP Configuration", draft-ietf-netmod-snmp-cfg-03 (work in progress), November 2013. - [draft-ieft-netconf-reverse-ssh] - Watsen, K., "NETCONF over SSH Call Home ", draft-ieft- - netconf-reverse-ssh-00 (work in progress), May 2014. - [draft-ietf-netmod-system-mgmt] Bierman, A., "A YANG Data Model for System Management ", draft-ieft-netmod-system-mgmt-16 (work in progress), May 2014. -10.2. Informative References +9.2. Informative References [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. -Appendix A. Example: SSH Transport Configuration +Appendix A. Examples + +A.1. SSH Transport Configuration + foo bar 831 - - config-mgr - - This entry requests the device to periodically - connect to the network manager. - + -
config-mgr1.example.com
+ east-data-center +
11.22.33.44
 -
config-mgr2.example.com
+ west-data-center +
55.66.77.88
 - - - - - ssh_host_key_cert - - - ssh_host_key_cert2 - - - - - - 5 - 10 - - - - last-connected - 10 - 3 - - - -Appendix B. Example: TLS Transport Configuration +A.2. TLS Transport Configuration - - -
192.0.2.1
- 6514 - - + foo bar + + 831 + - - - log-monitor - - This entry requests the device to maintain a - persistent connect to the network manager. - + config-mgr + -
log-monitor1.example.com
+ east-data-center +
11.22.33.44
 -
log-monitor2.example.com
+ west-data-center +
55.66.77.88
+ - - - - - - - 5 - 3 - - - - - - first-listed - 10 - 4 - - - + - - -Appendix C. Example: TLS Authentication Configuration - - - - - + QW4gRWFzdGVyIGVnZywgZm9yIHRob3NlIHdobyBtaWdodCBsb29rICA6KQo= - SSBhbSB0aGUgZWdnIG1hbiwgdGhleSBhcmUgdGhlIGVnZyBtZW4uCg== SSBhbSB0aGUgd2FscnVzLCBnb28gZ29vIGcnam9vYi4K - 1 11:0A:05:11:00 x509c2n:san-any 2 11:0A:05:11:00 x509c2n:specified @@ -1318,60 +1202,46 @@ a8gc8]klh59 admin 2013-01-01T00:00:00Z 2014-01-01T00:00:00Z + + - - - - -Appendix D. Change Log - -D.1. I-D to 00 - - o Changed title to "NETCONF Server Configuration Model" - - o Mapped inbound/outbound to listen/call-home - - o Restructured YANG module to place transport selection deeper into - the tree, providing a more intuitive data model +Appendix B. Change Log +B.1. 00 to 01 - o Added section "Keep-Alives for SSH and TLS" + o Restructured document so it flows better - o Updated the Security Considerations section + o Added trusted-ca-certs and trusted-client-certs objects into the + ietf-system-tls-auth module - o Added text for supporting VRFs via augments +B.2. 01 to 02 - o Factored the TLS-AUTH config into another module augmenting the - "ietf-system" module + o removed the "one-to-many" construct -D.2. 00 to 01 + o removed "address" as a key field - o Restructured document so it flows better + o removed "network-manager" terminology - o Added trusted-ca-certs and trusted-client-certs objects into the - ietf-system-tls-auth module + o moved open issues to github issues -Appendix E. Open Issues + o brought TLS client auth back into model - o NETCONF implementations typically have config parameters such as - session timeouts or hello timeouts. Shall they be included in - this model? +Appendix C. Open Issues - o Do we need knobs to enable/disable call-home without the need to - remove all the call-home client configuration? + Please see: https://github.com/netconf-wg/server-model/issues. Authors' Addresses Kent Watsen Juniper Networks EMail: kwatsen@juniper.net Juergen Schoenwaelder Jacobs University Bremen