YANG Groupings for TCP Clients and TCP Servers
draft-ietf-netconf-tcp-client-server-07
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| Authors | Kent Watsen , Michael Scharf | ||
| Last updated | 2020-07-08 | ||
| Replaces | draft-kwatsen-netconf-tcp-client-server | ||
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draft-ietf-netconf-tcp-client-server-07
NETCONF Working Group K. Watsen
Internet-Draft Watsen Networks
Intended status: Standards Track M. Scharf
Expires: 9 January 2021 Hochschule Esslingen
8 July 2020
YANG Groupings for TCP Clients and TCP Servers
draft-ietf-netconf-tcp-client-server-07
Abstract
This document defines three YANG 1.1 [RFC7950] modules to support the
configuration of TCP clients and TCP servers, either as standalone or
in conjunction with a stack protocol layer specific configurations.
Editorial Note (To be removed by RFC Editor)
This draft contains 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.
Artwork in this document contains shorthand references to drafts in
progress. Please apply the following replacements:
* "DDDD" --> the assigned RFC value for this draft
Artwork in this document contains placeholder values for the date of
publication of this draft. Please apply the following replacement:
* "2020-07-08" --> the publication date of this draft
The following Appendix section is to be removed prior to publication:
* Appendix A. Change Log
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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 https://datatracker.ietf.org/drafts/current/.
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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 9 January 2021.
Copyright Notice
Copyright (c) 2020 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 (https://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
1.1. Relation to other RFCs . . . . . . . . . . . . . . . . . 3
1.2. Specification Language . . . . . . . . . . . . . . . . . 5
1.3. Adherence to the NMDA . . . . . . . . . . . . . . . . . . 5
2. The "ietf-tcp-common" Module . . . . . . . . . . . . . . . . 5
2.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 5
2.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 7
2.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 8
3. The "ietf-tcp-client" Module . . . . . . . . . . . . . . . . 11
3.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 11
3.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 13
3.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 13
4. The "ietf-tcp-server" Module . . . . . . . . . . . . . . . . 20
4.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 20
4.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 21
4.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 21
5. Security Considerations . . . . . . . . . . . . . . . . . . . 24
5.1. The "ietf-tcp-common" YANG Module . . . . . . . . . . . . 24
5.2. The "ietf-tcp-client" YANG Module . . . . . . . . . . . . 25
5.3. The "ietf-tcp-server" YANG Module . . . . . . . . . . . . 26
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
6.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 26
6.2. The YANG Module Names Registry . . . . . . . . . . . . . 27
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.1. Normative References . . . . . . . . . . . . . . . . . . 27
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7.2. Informative References . . . . . . . . . . . . . . . . . 28
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 29
A.1. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 29
A.2. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 30
A.3. 02 to 03 . . . . . . . . . . . . . . . . . . . . . . . . 30
A.4. 03 to 04 . . . . . . . . . . . . . . . . . . . . . . . . 30
A.5. 04 to 05 . . . . . . . . . . . . . . . . . . . . . . . . 30
A.6. 05 to 06 . . . . . . . . . . . . . . . . . . . . . . . . 30
A.7. 06 to 07 . . . . . . . . . . . . . . . . . . . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30
1. Introduction
This document defines three YANG 1.1 [RFC7950] modules to support the
configuration of TCP clients and TCP servers, either as standalone or
in conjunction with a stack protocol layer specific configurations.
1.1. Relation to other RFCs
This document presents one or more YANG modules [RFC7950] that are
part of a collection of RFCs that work together to define
configuration modules for clients and servers of both the NETCONF
[RFC6241] and RESTCONF [RFC8040] protocols.
The modules have been defined in a modular fashion to enable their
use by other efforts, some of which are known to be in progress at
the time of this writing, with many more expected to be defined in
time.
The relationship between the various RFCs in the collection is
presented in the below diagram. The labels in the diagram represent
the primary purpose provided by each RFC. Links the each RFC are
provided below the diagram.
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crypto-types
^ ^
/ \
/ \
truststore keystore
^ ^ ^ ^
| +---------+ | |
| | | |
| +------------+ |
tcp-client-server | / | |
^ ^ ssh-client-server | |
| | ^ tls-client-server
| | | ^ ^ http-client-server
| | | | | ^
| | | +-----+ +---------+ |
| | | | | |
| +-----------|--------|--------------+ | |
| | | | | |
+-----------+ | | | | |
| | | | | |
| | | | | |
netconf-client-server restconf-client-server
+=======================+===========================================+
| Label in Diagram | Originating RFC |
+=======================+===========================================+
| crypto-types | [I-D.ietf-netconf-crypto-types] |
+-----------------------+-------------------------------------------+
| truststore | [I-D.ietf-netconf-trust-anchors] |
+-----------------------+-------------------------------------------+
| keystore | [I-D.ietf-netconf-keystore] |
+-----------------------+-------------------------------------------+
| tcp-client-server | [I-D.ietf-netconf-tcp-client-server] |
+-----------------------+-------------------------------------------+
| ssh-client-server | [I-D.ietf-netconf-ssh-client-server] |
+-----------------------+-------------------------------------------+
| tls-client-server | [I-D.ietf-netconf-tls-client-server] |
+-----------------------+-------------------------------------------+
| http-client-server | [I-D.ietf-netconf-http-client-server] |
+-----------------------+-------------------------------------------+
| netconf-client-server | [I-D.ietf-netconf-netconf-client-server] |
+-----------------------+-------------------------------------------+
|restconf-client-server | [I-D.ietf-netconf-restconf-client-server] |
+-----------------------+-------------------------------------------+
Table 1: Label to RFC Mapping
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1.2. Specification Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.3. Adherence to the NMDA
This document in compliant with the Network Management Datastore
Architecture (NMDA) [RFC8342]. It does not define any protocol
accessible nodes that are "config false".
2. The "ietf-tcp-common" Module
2.1. Data Model Overview
2.1.1. Model Scope
This document defines a common "grouping" statement for basic TCP
connection parameters that matter to applications. In some TCP
stacks, such parameters can also directly be set by an application
using system calls, such as the socket API. The base YANG model in
this document focuses on modeling TCP keep-alives. This base model
can be extended as needed.
2.1.2. Features
The following diagram lists all the "feature" statements defined in
the "ietf-tcp-common" module:
Features:
+-- keepalives-supported
2.1.3. Groupings
The following diagram lists all the "grouping" statements defined in
the "ietf-keystore" module:
Groupings:
+-- tcp-common-grouping
+-- tcp-connection-grouping
Each of these groupings are presented in the following subsections.
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2.1.3.1. The "tcp-common-grouping" Grouping
The following tree diagram [RFC8340] illustrates the "tcp-common-
grouping" grouping:
grouping tcp-common-grouping
+-- keepalives! {keepalives-supported}?
+-- idle-time uint16
+-- max-probes uint16
+-- probe-interval uint16
Comments:
* The "keepalives" node is a "presence" node so that the decendent
nodes' "mandatory true" doesn't imply that keepalives must be
configured.
* The "idle-time", "max-probes", and "probe-interval" nodes have the
common meanings. Please see the YANG module in Section 2.3 for
details.
2.1.3.2. The "tcp-connection-grouping" Grouping
The following tree diagram [RFC8340] illustrates the "tcp-connection-
grouping" grouping:
grouping tcp-connection-grouping
+---u tcp-common-grouping
Comments:
* This grouping uses the "tcp-common-grouping" grouping discussed in
Section 2.1.3.1.
2.1.4. Protocol-accessible Nodes
The "ietf-tcp-common" module does not contain any protocol-accessible
nodes.
2.1.5. Guidelines for Configuring TCP Keep-Alives
Network stacks may include "keep-alives" in their TCP
implementations, although this practice is not universally accepted.
If keep-alives are included, [RFC1122] [RFC793bis] mandates that the
application MUST be able to turn them on or off for each TCP
connection, and that they MUST default to off.
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Keep-alive mechanisms exist in many protocols. Depending on the
protocol stack, TCP keep-alives may only be one out of several
alternatives. Which mechanism(s) to use depends on the use case and
application requirements. If keep-alives are needed by an
application, it is RECOMMENDED that the aliveness check happens only
at the protocol layers that are meaningful to the application.
A TCP keep-alive mechanism SHOULD only be invoked in server
applications that might otherwise hang indefinitely and consume
resources unnecessarily if a client crashes or aborts a connection
during a network failure [RFC1122]. TCP keep-alives may consume
significant resources both in the network and in endpoints (e.g.,
battery power). In addition, frequent keep-alives risk network
congestion. The higher the frequency of keep-alives, the higher the
overhead.
Given the cost of keep-alives, parameters have to be configured
carefully:
* The default idle interval (leaf "idle-time") MUST default to no
less than two hours, i.e., 7200 seconds [RFC1122]. A lower value
MAY be configured, but keep-alive messages SHOULD NOT be
transmitted more frequently than once every 15 seconds. Longer
intervals SHOULD be used when possible.
* The maximum number of sequential keep-alive probes that can fail
(leaf "max-probes") trades off responsiveness and robustness
against packet loss. ACK segments that contain no data are not
reliably transmitted by TCP. Consequently, if a keep-alive
mechanism is implemented it MUST NOT interpret failure to respond
to any specific probe as a dead connection [RFC1122]. Typically a
single-digit number should suffice.
* TCP implementations may include a parameter for the number of
seconds between TCP keep-alive probes (leaf "probe-interval"). In
order to avoid congestion, the time interval between probes MUST
NOT be smaller than one second. Significantly longer intervals
SHOULD be used. It is important to note that keep-alive probes
(or replies) can get dropped due to network congestion. Sending
further probe messages into a congested path after a short
interval, without backing off timers, could cause harm and result
in a congestion collapse. Therefore it is essential to pick a
large, conservative value for this interval.
2.2. Example Usage
This section presents an example showing the "tcp-common-grouping"
populated with some data.
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<tcp-common xmlns="urn:ietf:params:xml:ns:yang:ietf-tcp-common">
<keepalives>
<idle-time>15</idle-time>
<max-probes>3</max-probes>
<probe-interval>30</probe-interval>
</keepalives>
</tcp-common>
2.3. YANG Module
The ietf-tcp-common YANG module references [RFC6991].
<CODE BEGINS> file "ietf-tcp-common@2020-07-08.yang"
module ietf-tcp-common {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-tcp-common";
prefix tcpcmn;
organization
"IETF NETCONF (Network Configuration) Working Group and the
IETF TCP Maintenance and Minor Extensions (TCPM) Working Group";
contact
"WG Web: <http://datatracker.ietf.org/wg/netconf/>
<http://datatracker.ietf.org/wg/tcpm/>
WG List: <mailto:netconf@ietf.org>
<mailto:tcpm@ietf.org>
Authors: Kent Watsen <mailto:kent+ietf@watsen.net>
Michael Scharf
<mailto:michael.scharf@hs-esslingen.de>";
description
"This module defines reusable groupings for TCP commons that
can be used as a basis for specific TCP common instances.
Copyright (c) 2020 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
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC DDDD
(https://www.rfc-editor.org/info/rfcDDDD); see the RFC
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itself for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
are to be interpreted as described in BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.";
revision 2020-07-08 {
description
"Initial version";
reference
"RFC DDDD: YANG Groupings for TCP Clients and TCP Servers";
}
// Features
feature keepalives-supported {
description
"Indicates that keepalives are supported.";
}
// Groupings
grouping tcp-common-grouping {
description
"A reusable grouping for configuring TCP parameters common
to TCP connections as well as the operating system as a
whole.";
container keepalives {
if-feature "keepalives-supported";
presence
"Indicates that keepalives are enabled. Present so that
the decendant nodes' 'mandatory true' doesn't imply that
this node must be configured.";
description
"Configures the keep-alive policy, to proactively test the
aliveness of the TCP peer. An unresponsive TCP peer is
dropped after approximately (idle-time + max-probes
* probe-interval) seconds.";
leaf idle-time {
type uint16 {
range "1..max";
}
units "seconds";
mandatory true;
description
"Sets the amount of time after which if no data has been
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received from the TCP peer, a TCP-level probe message
will be sent to test the aliveness of the TCP peer.
Two hours (7200 seconds) is safe value, per RFC 1122.";
reference
"RFC 1122:
Requirements for Internet Hosts -- Communication Layers";
}
leaf max-probes {
type uint16 {
range "1..max";
}
mandatory true;
description
"Sets the maximum number of sequential keep-alive probes
that can fail to obtain a response from the TCP peer
before assuming the TCP peer is no longer alive.";
}
leaf probe-interval {
type uint16 {
range "1..max";
}
units "seconds";
mandatory true;
description
"Sets the time interval between failed probes. The interval
SHOULD be significantly longer than one second in order to
avoid harm on a congested link.";
}
} // container keepalives
} // grouping tcp-common-grouping
grouping tcp-connection-grouping {
description
"A reusable grouping for configuring TCP parameters common
to TCP connections.";
uses tcp-common-grouping;
}
}
<CODE ENDS>
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3. The "ietf-tcp-client" Module
3.1. Data Model Overview
3.1.1. Features
The following diagram lists all the "feature" statements defined in
the "ietf-tcp-client" module:
Features:
+-- local-binding-supported
+-- tcp-client-keepalives
+-- proxy-connect
+-- socks5-gss-api
+-- socks5-username-password
3.1.2. Groupings
The following diagram lists all the "grouping" statements defined in
the "ietf-tcp-client" module:
Groupings:
+-- tcp-client-grouping
Each of these groupings are presented in the following subsections.
3.1.2.1. The "tcp-client-grouping" Grouping
The following tree diagram [RFC8340] illustrates the "tcp-client-
grouping" grouping:
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grouping tcp-client-grouping
+-- remote-address inet:host
+-- remote-port? inet:port-number
+-- local-address? inet:ip-address
| {local-binding-supported}?
+-- local-port? inet:port-number
| {local-binding-supported}?
+-- proxy-server! {proxy-connect}?
| +-- (proxy-type)
| +--:(socks4)
| | +-- socks4-parameters
| | +-- remote-address inet:ip-address
| | +-- remote-port? inet:port-number
| +--:(socks4a)
| | +-- socks4a-parameters
| | +-- remote-address inet:host
| | +-- remote-port? inet:port-number
| +--:(socks5)
| +-- socks5-parameters
| +-- remote-address inet:host
| +-- remote-port? inet:port-number
| +-- authentication-parameters!
| +-- (auth-type)
| +--:(gss-api) {socks5-gss-api}?
| | +-- gss-api
| +--:(username-password)
| {socks5-username-password}?
| +-- username-password
| +-- username? string
| +-- password? string
+---u tcpcmn:tcp-connection-grouping
Comments:
* The "remote-address" node, which is mandatory, may be configured
as an IPv4 address, an IPv6 address, a hostname.
* The "remote-port" node is not mandatory, but its default value is
the invalid value '0', thus forcing the consuming data model to
refine it in order to provide it an appropriate default value.
* The "local-address" node, which is enabled by the "local-binding-
supported" feature (Section 2.1.2), may be configured as an IPv4
address, an IPv6 address, or a wildcard value.
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* The "local-port" node, which is enabled by the "local-binding-
supported" feature (Section 2.1.2), is not mandatory. Its default
value is '0', indicating that the operating system can pick an
arbitrary port number.
* The "proxy-server" node is enabled by a "feature" statement and,
for servers that enable it, is a "presence" container so that the
decendent "mandatory true" choice node doesn't imply that the
proxt-server node must be configured.
* This grouping uses the "tcp-connection-grouping" grouping
discussed in Section 2.1.3.2.
3.1.3. Protocol-accessible Nodes
The "ietf-tcp-client" module does not contain any protocol-accessible
nodes.
3.2. Example Usage
This section presents an example showing the "tcp-client-grouping"
populated with some data.
<tcp-client xmlns="urn:ietf:params:xml:ns:yang:ietf-tcp-client">
<remote-address>www.example.com</remote-address>
<remote-port>443</remote-port>
<local-address>0.0.0.0</local-address>
<local-port>0</local-port>
<keepalives>
<idle-time>15</idle-time>
<max-probes>3</max-probes>
<probe-interval>30</probe-interval>
</keepalives>
</tcp-client>
3.3. YANG Module
The ietf-tcp-client YANG module references [RFC6991].
<CODE BEGINS> file "ietf-tcp-client@2020-07-08.yang"
module ietf-tcp-client {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-tcp-client";
prefix tcpc;
import ietf-inet-types {
prefix inet;
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reference
"RFC 6991: Common YANG Data Types";
}
import ietf-netconf-acm {
prefix nacm;
reference
"RFC 8341: Network Configuration Access Control Model";
}
import ietf-tcp-common {
prefix tcpcmn;
reference
"RFC DDDD: YANG Groupings for TCP Clients and TCP Servers";
}
organization
"IETF NETCONF (Network Configuration) Working Group and the
IETF TCP Maintenance and Minor Extensions (TCPM) Working Group";
contact
"WG Web: <http://datatracker.ietf.org/wg/netconf/>
<http://datatracker.ietf.org/wg/tcpm/>
WG List: <mailto:netconf@ietf.org>
<mailto:tcpm@ietf.org>
Authors: Kent Watsen <mailto:kent+ietf@watsen.net>
Michael Scharf
<mailto:michael.scharf@hs-esslingen.de>";
description
"This module defines reusable groupings for TCP clients that
can be used as a basis for specific TCP client instances.
Copyright (c) 2020 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
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC DDDD
(https://www.rfc-editor.org/info/rfcDDDD); see the RFC
itself for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
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'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
are to be interpreted as described in BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.";
revision 2020-07-08 {
description
"Initial version";
reference
"RFC DDDD: YANG Groupings for TCP Clients and TCP Servers";
}
// Features
feature local-binding-supported {
description
"Indicates that the server supports configuring local
bindings (i.e., the local address and local port) for
TCP clients.";
}
feature tcp-client-keepalives {
description
"Per socket TCP keepalive parameters are configurable for
TCP clients on the server implementing this feature.";
}
feature proxy-connect {
description
"Proxy connection configuration is configurable for
TCP clients on the server implementing this feature.";
}
feature socks5-gss-api {
description
"Indicates that the server supports authenticating
using GSSAPI when initiating TCP connections via
and SOCKS Version 5 proxy server.";
reference
"RFC 1928: SOCKS Protocol Version 5";
}
feature socks5-username-password {
description
"Indicates that the server supports authenticating
using username/password when initiating TCP
connections via and SOCKS Version 5 proxy
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server.";
reference
"RFC 1928: SOCKS Protocol Version 5";
}
// Groupings
grouping tcp-client-grouping {
description
"A reusable grouping for configuring a TCP client.
Note that this grouping uses fairly typical descendent
node names such that a stack of 'uses' statements will
have name conflicts. It is intended that the consuming
data model will resolve the issue (e.g., by wrapping
the 'uses' statement in a container called
'tcp-client-parameters'). This model purposely does
not do this itself so as to provide maximum flexibility
to consuming models.";
leaf remote-address {
type inet:host;
mandatory true;
description
"The IP address or hostname of the remote peer to
establish a connection with. If a domain name is
configured, then the DNS resolution should happen on
each connection attempt. If the DNS resolution
results in multiple IP addresses, the IP addresses
are tried according to local preference order until
a connection has been established or until all IP
addresses have failed.";
}
leaf remote-port {
type inet:port-number;
default "0";
description
"The IP port number for the remote peer to establish a
connection with. An invalid default value (0) is used
(instead of 'mandatory true') so that as application
level data model may 'refine' it with an application
specific default port number value.";
}
leaf local-address {
if-feature "local-binding-supported";
type inet:ip-address;
description
"The local IP address/interface (VRF?) to bind to for when
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connecting to the remote peer. INADDR_ANY ('0.0.0.0') or
INADDR6_ANY ('0:0:0:0:0:0:0:0' a.k.a. '::') MAY be used to
explicitly indicate the implicit default, that the server
can bind to any IPv4 or IPv6 addresses, respectively.";
}
leaf local-port {
if-feature "local-binding-supported";
type inet:port-number;
default "0";
description
"The local IP port number to bind to for when connecting
to the remote peer. The port number '0', which is the
default value, indicates that any available local port
number may be used.";
}
container proxy-server {
if-feature "proxy-connect";
presence
"Indicates that a proxy connection is configured.
Present so that the 'proxy-type' node's 'mandatory
true' doesn't imply that the proxy connection
must be configured.";
choice proxy-type {
mandatory true;
description
"Selects a proxy connection protocol.";
case socks4 {
container socks4-parameters {
leaf remote-address {
type inet:ip-address;
mandatory true;
description
"The IP address of the proxy server.";
}
leaf remote-port {
type inet:port-number;
default "1080";
description
"The IP port number for the proxy server.";
}
description
"Parameters for connecting to a TCP-based proxy
server using the SOCKS4 protocol.";
reference
"SOCKS, Proceedings: 1992 Usenix Security Symposium.";
}
}
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case socks4a {
container socks4a-parameters {
leaf remote-address {
type inet:host;
mandatory true;
description
"The IP address or hostname of the proxy server.";
}
leaf remote-port {
type inet:port-number;
default "1080";
description
"The IP port number for the proxy server.";
}
description
"Parameters for connecting to a TCP-based proxy
server using the SOCKS4a protocol.";
reference
"SOCKS Proceedings:
1992 Usenix Security Symposium.
OpenSSH message:
SOCKS 4A: A Simple Extension to SOCKS 4 Protocol
https://www.openssh.com/txt/socks4a.protocol";
}
}
case socks5 {
container socks5-parameters {
leaf remote-address {
type inet:host;
mandatory true;
description
"The IP address or hostname of the proxy server.";
}
leaf remote-port {
type inet:port-number;
default "1080";
description
"The IP port number for the proxy server.";
}
container authentication-parameters {
presence
"Indicates that an authentication mechanism
has been configured. Present so that the
'auth-type' node's 'mandatory true' doesn't
imply that an authentication mechanism
must be configured.";
description
"A container for SOCKS Version 5 authentication
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mechanisms.
A complete list of methods is defined at:
https://www.iana.org/assignments/socks-methods
/socks-methods.xhtml.";
reference
"RFC 1928: SOCKS Protocol Version 5";
choice auth-type {
mandatory true;
description
"A choice amongst supported SOCKS Version 5
authentication mechanisms.";
case gss-api {
if-feature socks5-gss-api;
container gss-api {
description
"Contains GSS-API configuration. Defines
as an empty container to enable specific
GSS-API configuration to be augmented in
by future modules.";
reference
"RFC 1928: SOCKS Protocol Version 5
RFC 2743: Generic Security Service
Application Program Interface
Version 2, Update 1";
}
}
case username-password {
if-feature socks5-username-password;
container username-password {
leaf username {
type string;
description
"The 'username' value to use.";
}
leaf password {
nacm:default-deny-all;
type string;
description
"The 'password' value to use.";
}
description
"Contains Username/Password configuration.";
reference
"RFC 1929: Username/Password Authentication
for SOCKS V5";
}
}
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}
}
description
"Parameters for connecting to a TCP-based proxy server
using the SOCKS5 protocol.";
reference
"RFC 1928: SOCKS Protocol Version 5";
}
}
}
description
"Proxy server settings.";
}
uses tcpcmn:tcp-connection-grouping {
augment "keepalives" {
if-feature "tcp-client-keepalives";
description
"Add an if-feature statement so that implementations
can choose to support TCP client keepalives.";
}
}
}
}
<CODE ENDS>
4. The "ietf-tcp-server" Module
4.1. Data Model Overview
4.1.1. Features
The following diagram lists all the "feature" statements defined in
the "ietf-tcp-server" module:
Features:
+-- tcp-server-keepalives
4.1.2. Groupings
The following diagram lists all the "grouping" statements defined in
the "ietf-tcp-server" module:
Groupings:
+-- tcp-server-grouping
Each of these groupings are presented in the following subsections.
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4.1.2.1. The "tcp-server-grouping" Grouping
The following tree diagram [RFC8340] illustrates the "tcp-server-
grouping" grouping:
grouping tcp-server-grouping
+-- local-address inet:ip-address
+-- local-port? inet:port-number
+---u tcpcmn:tcp-connection-grouping
Comments:
* The "local-address" node, which is mandatory, may be configured as
an IPv4 address, an IPv6 address, or a wildcard value.
* The "local-port" node is not mandatory, but its default value is
the invalid value '0', thus forcing the consuming data model to
refine it in order to provide it an appropriate default value.
* This grouping uses the "tcp-connection-grouping" grouping
discussed in Section 2.1.3.2.
4.1.3. Protocol-accessible Nodes
The "ietf-tcp-server" module does not contain any protocol-accessible
nodes.
4.2. Example Usage
This section presents an example showing the "tcp-server-grouping"
populated with some data.
<tcp-server xmlns="urn:ietf:params:xml:ns:yang:ietf-tcp-server">
<local-address>10.20.30.40</local-address>
<local-port>7777</local-port>
<keepalives>
<idle-time>15</idle-time>
<max-probes>3</max-probes>
<probe-interval>30</probe-interval>
</keepalives>
</tcp-server>
4.3. YANG Module
The ietf-tcp-server YANG module references [RFC6991].
<CODE BEGINS> file "ietf-tcp-server@2020-07-08.yang"
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module ietf-tcp-server {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-tcp-server";
prefix tcps;
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-tcp-common {
prefix tcpcmn;
reference
"RFC DDDD: YANG Groupings for TCP Clients and TCP Servers";
}
organization
"IETF NETCONF (Network Configuration) Working Group and the
IETF TCP Maintenance and Minor Extensions (TCPM) Working Group";
contact
"WG Web: <http://datatracker.ietf.org/wg/netconf/>
<http://datatracker.ietf.org/wg/tcpm/>
WG List: <mailto:netconf@ietf.org>
<mailto:tcpm@ietf.org>
Authors: Kent Watsen <mailto:kent+ietf@watsen.net>
Michael Scharf
<mailto:michael.scharf@hs-esslingen.de>";
description
"This module defines reusable groupings for TCP servers that
can be used as a basis for specific TCP server instances.
Copyright (c) 2020 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
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC DDDD
(https://www.rfc-editor.org/info/rfcDDDD); see the RFC
itself for full legal notices.
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The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
are to be interpreted as described in BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.";
revision 2020-07-08 {
description
"Initial version";
reference
"RFC DDDD: YANG Groupings for TCP Clients and TCP Servers";
}
// Features
feature tcp-server-keepalives {
description
"Per socket TCP keepalive parameters are configurable for
TCP servers on the server implementing this feature.";
}
// Groupings
grouping tcp-server-grouping {
description
"A reusable grouping for configuring a TCP server.
Note that this grouping uses fairly typical descendent
node names such that a stack of 'uses' statements will
have name conflicts. It is intended that the consuming
data model will resolve the issue (e.g., by wrapping
the 'uses' statement in a container called
'tcp-server-parameters'). This model purposely does
not do this itself so as to provide maximum flexibility
to consuming models.";
leaf local-address {
type inet:ip-address;
mandatory true;
description
"The local IP address to listen on for incoming
TCP client connections. INADDR_ANY (0.0.0.0) or
INADDR6_ANY (0:0:0:0:0:0:0:0 a.k.a. ::) MUST be
used when the server is to listen on all IPv4 or
IPv6 addresses, respectively.";
}
leaf local-port {
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type inet:port-number;
default "0";
description
"The local port number to listen on for incoming TCP
client connections. An invalid default value (0)
is used (instead of 'mandatory true') so that an
application level data model may 'refine' it with
an application specific default port number value.";
}
uses tcpcmn:tcp-connection-grouping {
augment "keepalives" {
if-feature "tcp-server-keepalives";
description
"Add an if-feature statement so that implementations
can choose to support TCP server keepalives.";
}
}
}
}
<CODE ENDS>
5. Security Considerations
5.1. The "ietf-tcp-common" YANG Module
The "ietf-tcp-common" YANG module defines "grouping" statements that
are designed to be accessed via YANG based management protocols, such
as NETCONF [RFC6241] and RESTCONF [RFC8040]. Both of these protocols
have mandatory-to-implement secure transport layers (e.g., SSH, TLS)
with mutual authentication.
The NETCONF access control model (NACM) [RFC8341] provides the means
to restrict access for particular users to a pre-configured subset of
all available protocol operations and content.
Since the module in this document only define groupings, these
considerations are primarily for the designers of other modules that
use these groupings.
None of the readable data nodes defined in this YANG module are
considered sensitive or vulnerable in network environments. The NACM
"default-deny-all" extension has not been set for any data nodes
defined in this module.
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None of the writable data nodes defined in this YANG module are
considered sensitive or vulnerable in network environments. The NACM
"default-deny-write" extension has not been set for any data nodes
defined in this module.
This module does not define any RPCs, actions, or notifications, and
thus the security consideration for such is not provided here.
5.2. The "ietf-tcp-client" YANG Module
The "ietf-tcp-client" YANG module defines "grouping" statements that
are designed to be accessed via YANG based management protocols, such
as NETCONF [RFC6241] and RESTCONF [RFC8040]. Both of these protocols
have mandatory-to-implement secure transport layers (e.g., SSH, TLS)
with mutual authentication.
The NETCONF access control model (NACM) [RFC8341] provides the means
to restrict access for particular users to a pre-configured subset of
all available protocol operations and content.
Since the module in this document only define groupings, these
considerations are primarily for the designers of other modules that
use these groupings.
One readable data node defined in this YANG module may be considered
sensitive or vulnerable in some network environments. This node is
as follows:
* The "proxy-server/socks5-parameters/authentication-parameters/
username-password/password" node:
The cleartext "password" node defined in the "tcp-client-
grouping" grouping is additionally sensitive to read operations
such that, in normal use cases, it should never be returned to
a client. For this reason, the NACM extension "default-deny-
all" has been applied to it.
None of the writable data nodes defined in this YANG module are
considered sensitive or vulnerable in network environments. The NACM
"default-deny-write" extension has not been set for any data nodes
defined in this module.
This module does not define any RPCs, actions, or notifications, and
thus the security consideration for such is not provided here.
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5.3. The "ietf-tcp-server" YANG Module
The "ietf-tcp-server" YANG module defines "grouping" statements that
are designed to be accessed via YANG based management protocols, such
as NETCONF [RFC6241] and RESTCONF [RFC8040]. Both of these protocols
have mandatory-to-implement secure transport layers (e.g., SSH, TLS)
with mutual authentication.
The NETCONF access control model (NACM) [RFC8341] provides the means
to restrict access for particular users to a pre-configured subset of
all available protocol operations and content.
Since the module in this document only define groupings, these
considerations are primarily for the designers of other modules that
use these groupings.
None of the readable data nodes defined in this YANG module are
considered sensitive or vulnerable in network environments. The NACM
"default-deny-all" extension has not been set for any data nodes
defined in this module.
None of the writable data nodes defined in this YANG module are
considered sensitive or vulnerable in network environments. The NACM
"default-deny-write" extension has not been set for any data nodes
defined in this module.
This module does not define any RPCs, actions, or notifications, and
thus the security consideration for such is not provided here.
6. IANA Considerations
6.1. The IETF XML Registry
This document registers two URIs in the "ns" subregistry of the IETF
XML Registry [RFC3688]. Following the format in [RFC3688], the
following registrations are requested:
URI: urn:ietf:params:xml:ns:yang:ietf-tcp-client
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-tcp-server
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
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6.2. The YANG Module Names Registry
This document registers two YANG modules in the YANG Module Names
registry [RFC6020]. Following the format in [RFC6020], the following
registrations are requested:
name: ietf-tcp-common
namespace: urn:ietf:params:xml:ns:yang:ietf-tcp-common
prefix: tcpcmn
reference: RFC DDDD
name: ietf-tcp-client
namespace: urn:ietf:params:xml:ns:yang:ietf-tcp-client
prefix: tcpc
reference: RFC DDDD
name: ietf-tcp-server
namespace: urn:ietf:params:xml:ns:yang:ietf-tcp-server
prefix: tcps
reference: RFC DDDD
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
7.2. Informative References
[I-D.ietf-netconf-crypto-types]
Watsen, K., "Common YANG Data Types for Cryptography",
Work in Progress, Internet-Draft, draft-ietf-netconf-
crypto-types-15, 20 May 2020,
<https://tools.ietf.org/html/draft-ietf-netconf-crypto-
types-15>.
[I-D.ietf-netconf-http-client-server]
Watsen, K., "YANG Groupings for HTTP Clients and HTTP
Servers", Work in Progress, Internet-Draft, draft-ietf-
netconf-http-client-server-03, 20 May 2020,
<https://tools.ietf.org/html/draft-ietf-netconf-http-
client-server-03>.
[I-D.ietf-netconf-keystore]
Watsen, K., "A YANG Data Model for a Keystore", Work in
Progress, Internet-Draft, draft-ietf-netconf-keystore-17,
20 May 2020, <https://tools.ietf.org/html/draft-ietf-
netconf-keystore-17>.
[I-D.ietf-netconf-netconf-client-server]
Watsen, K., "NETCONF Client and Server Models", Work in
Progress, Internet-Draft, draft-ietf-netconf-netconf-
client-server-19, 20 May 2020,
<https://tools.ietf.org/html/draft-ietf-netconf-netconf-
client-server-19>.
[I-D.ietf-netconf-restconf-client-server]
Watsen, K., "RESTCONF Client and Server Models", Work in
Progress, Internet-Draft, draft-ietf-netconf-restconf-
client-server-19, 20 May 2020,
<https://tools.ietf.org/html/draft-ietf-netconf-restconf-
client-server-19>.
[I-D.ietf-netconf-ssh-client-server]
Watsen, K. and G. Wu, "YANG Groupings for SSH Clients and
SSH Servers", Work in Progress, Internet-Draft, draft-
ietf-netconf-ssh-client-server-19, 20 May 2020,
<https://tools.ietf.org/html/draft-ietf-netconf-ssh-
client-server-19>.
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[I-D.ietf-netconf-tcp-client-server]
Watsen, K. and M. Scharf, "YANG Groupings for TCP Clients
and TCP Servers", Work in Progress, Internet-Draft, draft-
ietf-netconf-tcp-client-server-06, 16 June 2020,
<https://tools.ietf.org/html/draft-ietf-netconf-tcp-
client-server-06>.
[I-D.ietf-netconf-tls-client-server]
Watsen, K. and G. Wu, "YANG Groupings for TLS Clients and
TLS Servers", Work in Progress, Internet-Draft, draft-
ietf-netconf-tls-client-server-19, 20 May 2020,
<https://tools.ietf.org/html/draft-ietf-netconf-tls-
client-server-19>.
[I-D.ietf-netconf-trust-anchors]
Watsen, K., "A YANG Data Model for a Truststore", Work in
Progress, Internet-Draft, draft-ietf-netconf-trust-
anchors-10, 20 May 2020, <https://tools.ietf.org/html/
draft-ietf-netconf-trust-anchors-10>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore Architecture
(NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
<https://www.rfc-editor.org/info/rfc8342>.
Appendix A. Change Log
This section is to be removed before publishing as an RFC.
A.1. 00 to 01
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* Added 'local-binding-supported' feature to TCP-client model.
* Added 'keepalives-supported' feature to TCP-common model.
* Added 'external-endpoint-values' container and 'external-
endpoints' feature to TCP-server model.
A.2. 01 to 02
* Removed the 'external-endpoint-values' container and 'external-
endpoints' feature from the TCP-server model.
A.3. 02 to 03
* Moved the common model section to be before the client and server
specific sections.
* Added sections "Model Scope" and "Usage Guidelines for Configuring
TCP Keep-Alives" to the common model section.
A.4. 03 to 04
* Fixed a few typos.
A.5. 04 to 05
* Removed commented out "grouping tcp-system-grouping" statement
kept for reviewers.
* Added a "Note to Reviewers" note to first page.
A.6. 05 to 06
* Added support for TCP proxies.
A.7. 06 to 07
* Expanded "Data Model Overview section(s) [remove "wall" of tree
diagrams].
* Updated the Security Considerations section.
Authors' Addresses
Kent Watsen
Watsen Networks
Email: kent+ietf@watsen.net
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Michael Scharf
Hochschule Esslingen - University of Applied Sciences
Email: michael.scharf@hs-esslingen.de
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