NETCONF Client and Server Models

NETCONF Client and Server Models Juniper Networks

kwatsen@juniper.net

Cisco Networks

garywu@cisco.com

Jacobs University Bremen

j.schoenwaelder@jacobs-university.de

Operations NETCONF Working Group This document defines two YANG modules, one module to configure a NETCONF client and the other module to configure a NETCONF server. Both modules support both the SSH and TLS transport protocols, and support both standard NETCONF and NETCONF Call Home connections. This draft contains many placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document. This document contains references to other drafts in progress, both in the Normative References section, as well as in body text throughout. Please update the following references to reflect their final RFC assignments: draft-ietf-netconf-system-keychain draft-ietf-netconf-ssh-client-server draft-ietf-netconf-tls-client-server Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements: XXXX --> the assigned RFC value for this draft YYYY --> the assigned RFC value for draft-ietf-netconf-ssh-client-server ZZZZ --> the assigned RFC value for draft-ietf-netconf-tls-client-server AAAA --> the assigned RFC value for draft-ietf-netconf-call-home Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement: 2016-07-08 --> the publication date of this draft The following two Appendix sections are to be removed prior to publication: Appendix A. Change Log Appendix B. Open Issues

This document defines two YANG modules, one module to configure a NETCONF client and the other module to configure a NETCONF server. Both modules support both the SSH and TLS transport protocols, and support both standard NETCONF and NETCONF Call Home connections. NETCONF is defined by . SSH is defined by , , and . TLS is defined by . NETCONF Call Home is defined by ).

The keywords "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 .

A simplified graphical representation of the data models is used in this document. The meaning of the symbols in these diagrams is as follows: Brackets "[" and "]" enclose list keys. Braces "{" and "}" enclose feature names, and indicate that the named feature must be present for the subtree to be present. Abbreviations before data node names: "rw" means configuration (read-write) and "ro" state data (read-only). Symbols after data node names: "?" means an optional node, "!" means a presence container, and "*" denotes a list and leaf-list. Parentheses enclose choice and case nodes, and case nodes are also marked with a colon (":"). Ellipsis ("...") stands for contents of subtrees that are not shown.

The NETCONF client model presented in this section supports both clients initiating connections to servers, as well as clients listening for connections from servers calling home. This model supports both the SSH and TLS transport protocols, using the SSH client and TLS client groupings defined in and respectively. All private keys and trusted certificates are held in the keychain model defined in . YANG feature statements are used to enable implementations to advertise which parts of the model the NETCONF client supports.

Note: all lines are folded at column 71 with no '\' character.

/kc:keychain/ trusted-ssh-host-keys/name | | +--rw trusted-ca-certs? -> /kc:keychain/ trusted-certificates/name {ssh-x509-certs}? | | +--rw trusted-server-certs? -> /kc:keychain/ trusted-certificates/name | +--rw client-auth | +--rw matches* [name] | +--rw name string | +--rw match* [name] | | +--rw name string | | +--rw trusted-ssh-host-keys? -> /kc:key chain/trusted-ssh-host-keys/name | | +--rw trusted-ca-certs? -> /kc:key chain/trusted-certificates/name | | +--rw trusted-server-certs? -> /kc:key chain/trusted-certificates/name | +--rw user-auth-credentials? -> /kc:keycha in/user-auth-credentials/user-auth-credential/username +--rw listen {listen}? +--rw max-sessions? uint16 +--rw idle-timeout? uint16 +--rw endpoint* [name] +--rw name string +--rw (transport) +--:(ssh) {ssh-listen}? +--rw ssh +--rw address? inet:ip-address +--rw port? inet:port-number +--rw server-auth | +--rw trusted-ssh-host-keys? -> /kc:keychain/ trusted-ssh-host-keys/name | +--rw trusted-ca-certs? -> /kc:keychain/ trusted-certificates/name {ssh-x509-certs}? | +--rw trusted-server-certs? -> /kc:keychain/ trusted-certificates/name +--rw client-auth +--rw matches* [name] +--rw name string +--rw match* [name] | +--rw name string | +--rw trusted-ssh-host-keys? -> /kc:key chain/trusted-ssh-host-keys/name | +--rw trusted-ca-certs? -> /kc:key chain/trusted-certificates/name | +--rw trusted-server-certs? -> /kc:key chain/trusted-certificates/name +--rw user-auth-credentials? -> /kc:keycha in/user-auth-credentials/user-auth-credential/username ]]>

The following example illustrates configuring a NETCONF client to initiate connections, using both the SSH and TLS transport protocols, as well as listening for call-home connections, again using both the SSH and TLS transport protocols. This example is consistent with the examples presented in Section 2.2 of .

corp-fw1

corp-fw1.example.com

deployment-specific-ca-certs

Bob

Intranet-facing listener

11.22.33.44

deployment-specific-ca-certs

explicitly-trusted-server-certs

explicitly-trusted-ssh-host-keys

deployment-specific-ca-certs

admin

explicitly-trusted-server-certs

admin

explicitly-trusted-ssh-host-keys

admin

]]>

This YANG module imports YANG types from and .

file "ietf-netconf-client@2016-07-08.yang" module ietf-netconf-client { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-client"; prefix "ncc"; import ietf-inet-types { prefix inet; reference "RFC 6991: Common YANG Data Types"; } import ietf-x509-cert-to-name { prefix x509c2n; reference "RFC 7407: A YANG Data Model for SNMP Configuration"; } import ietf-ssh-client { prefix ss; revision-date 2016-07-08; // stable grouping definitions reference "RFC YYYY: SSH Client and Server Models"; } import ietf-tls-client { prefix ts; revision-date 2016-07-08; // stable grouping definitions reference "RFC ZZZZ: TLS Client and Server Models"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: WG List: WG Chair: Mehmet Ersue WG Chair: Mahesh Jethanandani Author: Kent Watsen Author: Gary Wu "; description "This module contains a collection of YANG definitions for configuring NETCONF servers. 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."; revision "2016-07-08" { description "Initial version"; reference "RFC XXXX: NETCONF Client and Server Models"; } // Features feature initiate { description "The 'initiate' feature indicates that the NETCONF client supports initiating NETCONF connections to NETCONF servers using at least one transport (e.g., SSH, TLS, etc.)."; } feature ssh-initiate { description "The ‘ssh-initiate’ feature indicates that the NETCONF client supports initiating SSH connections to NETCONF servers."; reference "RFC 6242: Using the NETCONF Protocol over Secure Shell (SSH)"; } feature tls-initiate { description "The ‘tls-initiate’ feature indicates that the NETCONF client supports initiating TLS connections to NETCONF servers."; reference "RFC 7589: Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication"; } feature listen { description "The 'listen' feature indicates that the NETCONF client supports opening a port to accept NETCONF server call home connections using at least one transport (e.g., SSH, TLS, etc.)."; } feature ssh-listen { description "The ‘ssh-listen’ feature indicates that the NETCONF client supports opening a port to listen for incoming NETCONF server call-home SSH connections."; reference "RFC AAAA: NETCONF Call Home and RESTCONF Call Home"; } feature tls-listen { description "The ‘tls-listen’ feature indicates that the NETCONF client supports opening a port to listen for incoming NETCONF server call-home TLS connections."; reference "RFC AAAA: NETCONF Call Home and RESTCONF Call Home"; } container netconf-client { description "Top-level container for NETCONF client configuration."; container initiate { if-feature initiate; description "Configures client intiating underlying TCP connections."; list netconf-server { key name; description "List of NETCONF servers the NETCONF client is to initiate connections to."; leaf name { type string; description "An arbitrary name for the NETCONF server."; } choice transport { mandatory true; description "Selects between available transports."; case ssh { if-feature ssh-initiate; container ssh { description "Specifies SSH-specific transport configuration."; leaf address { type inet:host; mandatory true; description "The IP address or hostname of the endpoint. If a hostname is configured and the DNS resolution results in more than one IP address, the NETCONF client will process the IP addresses as if they had been explicitly configured in place of the hostname."; } leaf port { type inet:port-number; default 830; description "The IP port for this endpoint. The NETCONF client will use the IANA-assigned well-known port if no value is specified."; } uses ss:initiating-ssh-client-grouping; } } /* case tls { if-feature tls-initiate; container tls { description "Specifies TLS-specific transport configuration."; uses endpoints-container { refine endpoints/endpoint/port { default 6513; } } uses ts:listening-tls-client-grouping { augment "client-auth" { description "Augments in the cert-to-name structure."; uses cert-maps-grouping; } } } } */ } } } // end initiate container listen { if-feature listen; description "Configures client accepting call-home TCP connections."; leaf max-sessions { type uint16; default 0; description "Specifies the maximum number of concurrent sessions that can be active at one time. The value 0 indicates that no artificial session limit should be used."; } leaf idle-timeout { type uint16; units "seconds"; default 3600; // one hour description "Specifies the maximum number of seconds that a NETCONF session may remain idle. A NETCONF session will be dropped if it is idle for an interval longer than this number of seconds. If set to zero, then the server will never drop a session because it is idle. Sessions that have a notification subscription active are never dropped."; } list endpoint { key name; description "List of endpoints to listen for NETCONF connections on."; leaf name { type string; description "An arbitrary name for the NETCONF listen endpoint."; } choice transport { mandatory true; description "Selects between available transports."; case ssh { if-feature ssh-listen; container ssh { description "SSH-specific listening configuration for inbound connections."; uses ss:listening-ssh-client-grouping { refine port { default 4334; } } } } /* case tls { if-feature tls-listen; container tls { description "TLS-specific listening configuration for inbound connections."; uses ts:listening-tls-client-grouping { refine port { default 4335; } augment "client-auth" { description "Augments in the cert-to-name structure."; uses cert-maps-grouping; } } } } */ } } } // end listen } grouping cert-maps-grouping { description "A grouping that defines a container around the cert-to-name structure defined in RFC 7407."; container cert-maps { uses x509c2n:cert-to-name; description "The cert-maps container is used by a TLS-based 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."; reference "RFC WWWW: NETCONF over TLS, Section 7"; } } }

]]>




      
        The NETCONF server model presented in this section supports servers
        both listening for connections as well as initiating call-home
        connections.

        This model also supports both the SSH and TLS transport
        protocols, using the SSH server and TLS server groupings defined in
         and 
         respectively.

        All private keys and trusted certificates are held in the
        keychain model defined in .

        YANG feature statements are used to enable implementations to advertise
        which parts of the model the NETCONF server supports.

        
          Note: all lines are folded at column 71 with no '\' character.
          
            
               /kc:keychain/p
rivate-keys/private-key/name
      |        |     |        +--:(certificate)
      |        |     |           +--rw certificate?   -> /kc:keychain/p
rivate-keys/private-key/certificate-chains/certificate-chain/name {ssh-
x509-certs}?
      |        |     +--rw client-cert-auth {ssh-x509-certs}?
      |        |        +--rw trusted-ca-certs?       -> /kc:keychain/t
rusted-certificates/name
      |        |        +--rw trusted-client-certs?   -> /kc:keychain/t
rusted-certificates/name
      |        +--:(tls) {tls-listen}?
      |           +--rw tls
      |              +--rw address?        inet:ip-address
      |              +--rw port?           inet:port-number
      |              +--rw certificates
      |              |  +--rw certificate* [name]
      |              |     +--rw name    -> /kc:keychain/private-keys/p
rivate-key/certificate-chains/certificate-chain/name
      |              +--rw client-auth
      |                 +--rw trusted-ca-certs?       -> /kc:keychain/t
rusted-certificates/name
      |                 +--rw trusted-client-certs?   -> /kc:keychain/t
rusted-certificates/name
      |                 +--rw cert-maps
      |                    +--rw cert-to-name* [id]
      |                       +--rw id             uint32
      |                       +--rw fingerprint    x509c2n:tls-fingerpr
int
      |                       +--rw map-type       identityref
      |                       +--rw name           string
      +--rw call-home {call-home}?
         +--rw netconf-client* [name]
            +--rw name                  string
            +--rw (transport)
            |  +--:(ssh) {ssh-call-home}?
            |  |  +--rw ssh
            |  |     +--rw endpoints
            |  |     |  +--rw endpoint* [name]
            |  |     |     +--rw name       string
            |  |     |     +--rw address    inet:host
            |  |     |     +--rw port?      inet:port-number
            |  |     +--rw host-keys
            |  |     |  +--rw host-key* [name]
            |  |     |     +--rw name           string
            |  |     |     +--rw (type)?
            |  |     |        +--:(public-key)
            |  |     |        |  +--rw public-key?    -> /kc:keychain/p
rivate-keys/private-key/name
            |  |     |        +--:(certificate)
            |  |     |           +--rw certificate?   -> /kc:keychain/p
rivate-keys/private-key/certificate-chains/certificate-chain/name {ssh-
x509-certs}?
            |  |     +--rw client-cert-auth {ssh-x509-certs}?
            |  |        +--rw trusted-ca-certs?       -> /kc:keychain/t
rusted-certificates/name
            |  |        +--rw trusted-client-certs?   -> /kc:keychain/t
rusted-certificates/name
            |  +--:(tls) {tls-call-home}?
            |     +--rw tls
            |        +--rw endpoints
            |        |  +--rw endpoint* [name]
            |        |     +--rw name       string
            |        |     +--rw address    inet:host
            |        |     +--rw port?      inet:port-number
            |        +--rw certificates
            |        |  +--rw certificate* [name]
            |        |     +--rw name    -> /kc:keychain/private-keys/p
rivate-key/certificate-chains/certificate-chain/name
            |        +--rw client-auth
            |           +--rw trusted-ca-certs?       -> /kc:keychain/t
rusted-certificates/name
            |           +--rw trusted-client-certs?   -> /kc:keychain/t
rusted-certificates/name
            |           +--rw cert-maps
            |              +--rw cert-to-name* [id]
            |                 +--rw id             uint32
            |                 +--rw fingerprint    x509c2n:tls-fingerpr
int
            |                 +--rw map-type       identityref
            |                 +--rw name           string
            +--rw connection-type
            |  +--rw (connection-type)?
            |     +--:(persistent-connection)
            |     |  +--rw persistent!
            |     |     +--rw idle-timeout?   uint32
            |     |     +--rw keep-alives
            |     |        +--rw max-wait?       uint16
            |     |        +--rw max-attempts?   uint8
            |     +--:(periodic-connection)
            |        +--rw periodic!
            |           +--rw idle-timeout?        uint16
            |           +--rw reconnect_timeout?   uint16
            +--rw reconnect-strategy
               +--rw start-with?     enumeration
               +--rw max-attempts?   uint8
]]>
            
          
        

        
          The following example illustrates configuring a NETCONF server
          to listen for NETCONF client connections using both the SSH and 
          TLS transport protocols, as well as configuring call-home to two
          NETCONF clients, one using SSH and the other using TLS.
          This example is consistent with the examples presented in
          Section 2.2 of .
          
            
              
  

    
    
      netconf/ssh
      
        11.22.33.44
        
          
            my-rsa-key
          
          
            TPM key
          
        
        
          
            deployment-specific-ca-certs
          
          
            explicitly-trusted-client-certs
          
        
      
    

    
    
      netconf/tls
      
        11.22.33.44
        
          ex-key-sect571r1-cert
        
        
          
            deployment-specific-ca-certs
          
          
            explicitly-trusted-client-certs
          
          
            
              1
              11:0A:05:11:00
              x509c2n:san-any
            
            
              2
              B3:4F:A1:8C:54
              x509c2n:specified
              scooby-doo
            
          
        
      
    

  
  

    
    
      config-mgr
      
        
          
            east-data-center
            11.22.33.44
          
          
            west-data-center
            55.66.77.88
          
        
        
          
            TPM key
          
        
        
          
            deployment-specific-ca-certs
          
          
            explicitly-trusted-client-certs
          
        
      
      
        
          300
          60
        
      
      
        last-connected
        3
      
    

    
    
      event-correlator
      
        
          
            east-data-center
            22.33.44.55
          
          
            west-data-center
            33.44.55.66
          
        
        
          ex-key-sect571r1-cert
        
        
          
            deployment-specific-ca-certs
          
          
            explicitly-trusted-client-certs
          
          
            
              1
              11:0A:05:11:00
              x509c2n:san-any
            
            
              2
              B3:4F:A1:8C:54
              x509c2n:specified
              scooby-doo
            
          
        
      
      
        
          300
          
            30
            3
          
        
      
      
        first-listed
        3
      
    

  

]]>
            
          
        

        
          This YANG module imports YANG types from  and .
          
            
               file "ietf-netconf-server@2016-07-08.yang"

module ietf-netconf-server {
  yang-version 1.1;

  namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-server";
  prefix "ncs";

  import ietf-inet-types {
    prefix inet;
    reference 
      "RFC 6991: Common YANG Data Types";
  }

  import ietf-x509-cert-to-name {
    prefix x509c2n;
    reference
      "RFC 7407: A YANG Data Model for SNMP Configuration";
  }  

  import ietf-ssh-server {
    prefix ss;
    revision-date 2016-07-08; // stable grouping definitions
    reference
      "RFC YYYY: SSH Client and Server Models";
  }

  import ietf-tls-server {
    prefix ts;
    revision-date 2016-07-08; // stable grouping definitions
    reference
      "RFC ZZZZ: TLS Client and Server Models";
  }

  organization
   "IETF NETCONF (Network Configuration) Working Group";

  contact
   "WG Web:   
    WG List:  

    WG Chair: Mehmet Ersue
              

    WG Chair: Mahesh Jethanandani
              

    Editor:   Kent Watsen
              ";


  description
   "This module contains a collection of YANG definitions for
    configuring NETCONF servers.

    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.";

  revision "2016-07-08" {
    description
     "Initial version";
    reference
     "RFC XXXX: NETCONF Client and Server Models";
  }


  // Features

  feature listen {
    description
     "The 'listen' feature indicates that the NETCONF server 
      supports opening a port to accept NETCONF client connections
      using at least one transport (e.g., SSH, TLS, etc.)."; 
  }

  feature ssh-listen {
    description
     "The 'ssh-listen' feature indicates that the NETCONF server 
      supports opening a port to accept NETCONF over SSH 
      client connections."; 
    reference
     "RFC 6242: Using the NETCONF Protocol over Secure Shell (SSH)";
  }

  feature tls-listen {
    description
     "The 'tls-listen' feature indicates that the NETCONF server 
      supports opening a port to accept NETCONF over TLS 
      client connections."; 
    reference
     "RFC 7589: Using the NETCONF Protocol over Transport
                Layer Security (TLS) with Mutual X.509
                Authentication";
  }

  feature call-home {
    description
     "The 'call-home' feature indicates that the NETCONF server
      supports initiating NETCONF call home connections to NETCONF
      clients using at least one transport (e.g., SSH, TLS, etc.).";
    reference
     "RFC YYYY: NETCONF Call Home and RESTCONF Call Home";
  }

  feature ssh-call-home {
    description
     "The 'ssh-call-home' feature indicates that the NETCONF 
      server supports initiating a NETCONF over SSH call
      home connection to NETCONF clients.";
    reference
     "RFC YYYY: NETCONF Call Home and RESTCONF Call Home";
  }

  feature tls-call-home {
    description
     "The 'tls-call-home' feature indicates that the NETCONF 
      server supports initiating a NETCONF over TLS call
      home connection to NETCONF clients.";
    reference
     "RFC YYYY: NETCONF Call Home and RESTCONF Call Home";
  }


  // top-level container  (groupings below)
  container netconf-server {
    description
      "Top-level container for NETCONF server configuration.";

    container session-options {  // SHOULD WE REMOVE THIS ALTOGETHER?
      description
        "NETCONF session options, independent of transport
         or connection strategy.";
      leaf hello-timeout {
        type uint16;
        units "seconds";
        default 600;
        description
          "Specifies the maximum number of seconds that a SSH/TLS
           connection may wait for a hello message to be received.
           A connection will be dropped if no hello message is 
           received before this number of seconds elapses.  If set
           to zero, then the server will wait forever for a hello
           message.";
      }
    }

    container listen {
      if-feature listen;
      description
        "Configures listen behavior";
      leaf max-sessions {
        type uint16;
        default 0;
        description
          "Specifies the maximum number of concurrent sessions
           that can be active at one time.  The value 0 indicates
           that no artificial session limit should be used.";
      }
      leaf idle-timeout {
        type uint16;
        units "seconds";
        default 3600; // one hour
        description
          "Specifies the maximum number of seconds that a NETCONF
           session may remain idle. A NETCONF session will be dropped
           if it is idle for an interval longer than this number of
           seconds.  If set to zero, then the server will never drop
           a session because it is idle.  Sessions that have a 
           notification subscription active are never dropped.";
      }
      list endpoint {
        key name;
        description
          "List of endpoints to listen for NETCONF connections on.";
        leaf name {
          type string;
          description
            "An arbitrary name for the NETCONF listen endpoint.";
        }
        choice transport {
          mandatory true;
          description
            "Selects between available transports.";
          case ssh {
            if-feature ssh-listen;
            container ssh {
              description
                "SSH-specific listening configuration for inbound
                 connections.";
              uses ss:listening-ssh-server-grouping {
                refine port {
                  default 830;
                }
              }
            }
          }
          case tls {
            if-feature tls-listen;
            container tls {
              description
                "TLS-specific listening configuration for inbound
                 connections.";
              uses ts:listening-tls-server-grouping {
                refine port {
                  default 6513;
                }
                augment "client-auth" {
                  description
                    "Augments in the cert-to-name structure.";
                  uses cert-maps-grouping;
                }
              }
            }
          }
        }
      }
    }

    container call-home {
      if-feature call-home;
      description
        "Configures call-home behavior";
      list netconf-client {
        key name;
        description
          "List of NETCONF clients the NETCONF server is to initiate
           call-home connections to.";
        leaf name {
          type string;
          description
            "An arbitrary name for the remote NETCONF client.";
        }
        choice transport {
          mandatory true;
          description
            "Selects between available transports.";
          case ssh {
            if-feature ssh-call-home;
            container ssh {
              description
                "Specifies SSH-specific call-home transport
                 configuration.";
              uses endpoints-container {
                refine endpoints/endpoint/port {
                  default 4334;
                }
              }
              uses ss:non-listening-ssh-server-grouping;
            }
          }
          case tls {
            if-feature tls-call-home;
            container tls {
              description
                "Specifies TLS-specific call-home transport
                 configuration.";
              uses endpoints-container {
                refine endpoints/endpoint/port {
                  default 4335;
                }
              }
              uses ts:non-listening-tls-server-grouping {
                augment "client-auth" {
                  description
                    "Augments in the cert-to-name structure.";
                  uses cert-maps-grouping;
                }
              }
            }
          }
        }
        container connection-type {
          description
           "Indicates the kind of connection to use.";
          choice connection-type {
            description
              "Selects between available connection types.";
            case persistent-connection {
              container persistent {
                presence true;
                description
                 "Maintain a persistent connection to the NETCONF 
                  client. If the connection goes down, immediately 
                  start trying to reconnect to it, using the 
                  reconnection strategy.
    
                  This connection type minimizes any NETCONF client
                  to NETCONF server data-transfer delay, albeit at 
                  the expense of holding resources longer.";
                leaf idle-timeout {
                  type uint32;
                  units "seconds";
                  default 86400;  // one day;
                  description
                    "Specifies the maximum number of seconds that a 
                     a NETCONF session may remain idle. A NETCONF 
                     session will be dropped if it is idle for an 
                     interval longer than this number of seconds.  
                     If set to zero, then the server will never drop
                     a session because it is idle.  Sessions that 
                     have a notification subscription active are 
                     never dropped.";
                }
                container keep-alives {
                  description
                    "Configures the keep-alive policy, to proactively
                     test the aliveness of the SSH/TLS client.  An
                     unresponsive SSH/TLS client will be dropped after
                     approximately max-attempts * max-wait seconds.";
                  reference
                    "RFC YYYY: NETCONF Call Home and RESTCONF Call
                     Home, Section 3.1, item S6";
                  leaf max-wait {
                    type uint16 {
                      range "1..max";
                    }
                    units seconds;
                    default 30;
                    description
                     "Sets the amount of time in seconds after which 
                      if no data has been received from the SSH/TLS
                      client, a SSH/TLS-level message will be sent 
                      to test the aliveness of the SSH/TLS client.";
                  }
                  leaf max-attempts {
                    type uint8;
                    default 3;
                    description
                     "Sets the maximum number of sequential keep-alive
                      messages that can fail to obtain a response from
                      the SSH/TLS client before assuming the SSH/TLS
                      client is no longer alive.";
                  }
                }
              }
            }
            case periodic-connection {
              container periodic {
                presence true;
                description
                 "Periodically connect to the NETCONF client, so that
                  the NETCONF client may deliver messages pending for
                  the NETCONF server.  The NETCONF client must close
                  the connection when it is ready to release it. Once
                  the connection has been closed, the NETCONF server
                  will restart its timer until the next connection.";
                leaf idle-timeout {
                  type uint16;
                  units "seconds";
                  default 300; // five minutes
                  description
                    "Specifies the maximum number of seconds that a 
                     a NETCONF session may remain idle. A NETCONF 
                     session will be dropped if it is idle for an 
                     interval longer than this number of seconds.  
                     If set to zero, then the server will never drop
                     a session because it is idle.  Sessions that 
                     have a notification subscription active are 
                     never dropped.";
                }
                leaf reconnect_timeout {
                  type uint16 {
                    range "1..max";
                  }
                  units minutes;
                  default 60;
                  description
                   "Sets the maximum amount of unconnected time the 
                    NETCONF server will wait before re-establishing
                    a connection to the NETCONF client.  The NETCONF
                    server may initiate a connection before this 
                    time if desired (e.g., to deliver an event
                    notification message).";
                }
              }
            }
          }
        }
        container reconnect-strategy {
          description
           "The reconnection strategy directs how a NETCONF server 
            reconnects to a NETCONF client, after discovering its
            connection to the client has dropped, even if due to a
            reboot.  The NETCONF server starts with the specified
            endpoint and tries to connect to it max-attempts times
            before trying the next endpoint in the list (round 
            robin).";
          leaf start-with {
            type enumeration {
              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.  If no previous
                   connection has ever been established, then the
                   first endpoint configured is used.   NETCONF 
                   servers SHOULD be able to remember the last 
                   endpoint connected to across reboots.";
              }
            }
            default first-listed;
            description
             "Specifies which of the NETCONF client's endpoints the
              NETCONF server should start with when trying to connect
              to the NETCONF client.";
          }
          leaf max-attempts {
            type uint8 {
              range "1..max";
            }
            default 3;
            description
             "Specifies the number times the NETCONF server tries to
              connect to a specific endpoint before moving on to the
              next endpoint in the list (round robin).";
          }
        }
      }
    }
  }


  grouping cert-maps-grouping {
    description
      "A grouping that defines a container around the
       cert-to-name structure defined in RFC 7407.";
    container cert-maps {
      uses x509c2n:cert-to-name;
      description
       "The cert-maps container is used by a TLS-based 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.";
      reference
        "RFC WWWW: NETCONF over TLS, Section 7";
    }
  }

 
  grouping endpoints-container {
    description
      "This grouping is used by both the ssh and tls containers
       for call-home configurations.";
    container endpoints {
      description
        "Container for the list of endpoints.";
      list endpoint {
        key name;
        min-elements 1;
        ordered-by user;
        description
          "User-ordered list of endpoints for this NETCONF client.
           Defining more than one enables high-availability.";
        leaf name {
          type string;
          description
            "An arbitrary name for this endpoint.";
        }
        leaf address {
          type inet:host;
          mandatory true;
          description
           "The IP address or hostname of the endpoint.  If a 
            hostname is configured and the DNS resolution results
            in more than one IP address, the NETCONF server 
            will process the IP addresses as if they had been
            explicitly configured in place of the hostname.";
        }
        leaf port {
          type inet:port-number;
          description
           "The IP port for this endpoint. The NETCONF server will
            use the IANA-assigned well-known port if no value is 
            specified.";
        }
      }
    }
  }

}



]]>
            

          
        

      


      
        Editorial: this section is a hold over from before, previously called
        "Objectives".  It was only written two support the "server" (not the "client").
        The question is if it's better to add the missing "client" parts, or remove
        this section altogether.

        The primary purpose of the YANG modules defined herein is
        to enable the configuration of the NETCONF client and servers.
        This scope includes the following objectives:
        
          The YANG module should support all current NETCONF 
          transports, namely NETCONF over SSH , 
          NETCONF over TLS , and to be 
          extensible to support future transports as necessary.
          Because implementations may not support all transports,
          the modules should use YANG "feature" statements
          so that implementations can accurately advertise which
          transports are supported.
        
        
          Servers may have a multiplicity of host-keys or server-certificates
             from which subsets may be selected for specific uses.  For instance,
             a NETCONF server may want to use one set of SSH host-keys when listening
             on port 830, and a different set of SSH host-keys when calling
             home.  The data models provided herein should enable configuration
             of which keys to use on a per-use basis.
        
        
          When a certificate is used to authenticate a NETCONF client,
             there is a need to configure the server to know how to authenticate the 
             certificates.  The server should be able to authenticate the client's
             certificate either by using path-validation to a configured trust anchor
             or by matching the client-certificate to one previously configured.
        
        
          When a client certificate is used for TLS client authentication,
             the NETCONF server must be able to derive a username from the 
             authenticated certificate.  Thus the modules defined herein should enable
             this mapping to be configured.
        
        
          The NETCONF protocols were originally defined as having the 
          server opening a port to listen for client connections.  More recently
          the NETCONF working group defined support for call-home 
          (), enabling the server to
          initiate the connection to the client.  Thus the modules defined herein
          should enable configuration for both listening for connections and
          calling home.  Because implementations may not support both listening
          for connections and calling home, YANG "feature" statements
          should be used so that implementation can accurately 
          advertise the connection types it supports.
        
        
          The following objectives only pertain to call home connections.
          
            A NETCONF server may be managed by more than one NETCONF client.
            For instance, a deployment may have one client for provisioning and
            another for fault monitoring.  Therefore, when it is desired for a
            server to initiate call home connections, it should be able to do
            so to more than one client.
          
          
            A NETCONF client managing a NETCONF server may implement a 
            high-availability strategy employing a multiplicity of
            active and/or passive endpoint.  Therefore, when it is
            desired for a server to initiate call home connections,
            it should be able to connect to any of the client's endpoints.
          
          
            Assuming a NETCONF client has more than one endpoint, then
            it becomes necessary to configure how a NETCONF server should
            reconnect to the client should it lose its connection to one
            the client's endpoints.  For instance, the NETCONF server may
            start with first endpoint defined in a user-ordered list of 
            endpoints or with the last endpoints it was connected to.
          
          
            NETCONF clients may vary greatly on how frequently they need
            to interact with a NETCONF server, how responsive interactions
            need to be, and how many simultaneous connections they can 
            support.  Some clients may need a persistent connection to
            servers to optimize real-time interactions, while others 
            prefer periodic interactions in order to minimize resource
            requirements.  Therefore, when it is necessary for server
            to initiate connections, it should be configurable if the
            connection is persistent or periodic.
          
          
            The reconnection strategy should apply to both 
            persistent and periodic connections.  How it
            applies to periodic connections becomes clear when
            considering that a periodic "connection" is
            a logical connection to a single server.  That is,
            the periods of unconnectedness are intentional as 
            opposed to due to external reasons.  A periodic
            "connection" should always reconnect to 
            the same server until it is no longer able to, at 
            which time the reconnection strategy guides how to
            connect to another server.
          
          
            If a persistent connection is desired, it is the 
            responsibility of the connection initiator to actively
            test the "aliveness" of the connection.  The connection
            initiator must immediately work to reestablish a 
            persistent connection as soon as the connection is
            lost.  How often the connection should be tested is
            driven by NETCONF client requirements, and therefore
            keep-alive settings should be configurable on a 
            per-client basis.
          
          
            If a periodic connection is desired, it is necessary for 
            the NETCONF server to know how often it should connect.  This
            frequency determines the maximum amount of time a NETCONF
            client may have to wait to send data to a server.  A server may
            connect to a client before this interval expires if desired
            (e.g., to send data to a client).
          
        
      

      
        A denial of service (DoS) attack MAY occur if the NETCONF server limits the
        maximum number of NETCONF sessions it will accept (i.e.  the 'max-sessions' field
        in the ietf-netconf-server module is not zero) and either the "hello-timeout"
        or "idle-timeout" fields in ietf-netconf-server module have been set to indicate
        the NETCONF server should wait forever (i.e. set to zero). 


      

      
        
          This document registers two URIs in the IETF XML 
          registry .  Following the format in 
          , the following registrations are
          requested:
          
            
                
            
          
        
        
          This document registers two YANG modules in the
          YANG Module Names registry .
          Following the format in , the
          the following registrations are requested:
          
            
                
            
          
        
      


      
        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,
        Mehmet Ersue, David Lamparter, Alan Luchuk, Ladislav Lhotka,
        Radek Krejci, Tom Petch, Phil Shafer, Sean Turner, and
        Bert Wijnen.
       
         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.



    
      
        &rfc2119;
        &rfc6020;
        &rfc6241;
        &rfc6242;
        &rfc6991;
        &rfc7407;
        &rfc7589;

        
          
            System Keychain Model
            
              Juniper Networks
            
            
          
          
        

        
          
            SSH Client and Server Models
            
              Juniper Networks
            
            
           
           
        

        
          
            TLS Client and Server Models
            
              Juniper Networks
            
            
           
           
        

      

      

        &rfc3688;
        &rfc4252;
        &rfc4253;
        &rfc4254;
        &rfc5246;


        
          
            
              NETCONF Call Home and RESTCONF Call Home
            
            
              Juniper Networks
            
            
          
          
        
      

      
        
          
            
              This draft was split out from draft-ietf-netconf-server-model-09.
              Added in previously missing ietf-netconf-client module.
              Added in new features 'listen' and 'call-home' so future transports
                 can be augmented in.
            
          
        
      

      
        Please see: https://github.com/netconf-wg/netconf-client-server/issues.