XEP-0279: Server IP Check

WARNING: This Standards-Track document is Experimental. Publication as an XMPP Extension Protocol does not imply approval of this proposal by the XMPP Standards Foundation. Implementation of the protocol described herein is encouraged in exploratory implementations, but production systems are advised to carefully consider whether it is appropriate to deploy implementations of this protocol before it advances to a status of Draft.

Table of Contents

1. Introduction

There are times when a client might want or need to discover what its external Internet Protocol (IP) address is, e.g. when gathering transport candidates for SOCKS5 Bytestreams [1] or Jingle ICE-UDP Transport Method [2]. One way to do so is for the client to ask the XMPP server to which it has connected. This simple specification defines such a method. The information provided by the server cannot necessarily be relied upon because there might be intermediate entities between the client and the server, but if the IP address returned by the server is different from the client's notion of its IP address then at the very least the client has received a hint that it might be behind a network address translator (NAT) and therefore cannot usefully provide its private IP address as a candidate for use in multimedia negotiations.

2. Protocol

First the client sends an IQ-get request to its server.

Example 1. Client requests its IP address from the server

<iq from='romeo@montague.lit/orchard'
    id='ik2s7159'
    type='get'>
  <ip xmlns='urn:xmpp:sic:0'/>
</iq>
  

The server then returns an IQ-result containing an <ip/> element whose XML character data specifies the client's IP address according to the server.

Example 2. Server returns IP address

<iq id='ik2s7159'
    to='romeo@montague.lit/orchard'
    type='result'>
  <ip xmlns='urn:xmpp:sic:0'>192.168.4.1</ip>
</iq>
  

The IP address could be IPv4 or IPv6.

Example 3. Server returns IPv6 address

<iq id='ik2s7159'
    to='romeo@montague.lit/orchard'
    type='result'>
  <ip xmlns='urn:xmpp:sic:0'>2001:db8::9:1</ip>
</iq>
  

3. Determining Support

If an entity supports this protocol, it MUST report that by including a service discovery feature of "urn:xmpp:sic:0" in response to disco#info requests (see Protocol Namespaces regarding issuance of one or more permanent namespaces).

Example 4. Service discovery information request

<iq from='romeo@montague.lit/orchard'
    id='ux71f395'
    to='montague.lit'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
  

Example 5. Service discovery information response

<iq from='montague.lit'
    id='ux71f395'
    to='romeo@montague.lit/orchard'
    type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <feature var='urn:xmpp:sic:0'/>
  </query>
</iq>
  

4. Security Considerations

RFC 3920 [3] specifies that client IP addresses shall not be made public. If a client requests its own IP address, that policy is not violated. However, a server MUST NOT return the IP address of another client (e.g., if a connected client sends a SIC request to the bare JID of another user); instead, it MUST return a <forbidden/> error.

5. IANA Considerations

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) [4].

6. XMPP Registrar Considerations

7. XML Schema

<?xml version='1.0' encoding='UTF-8'?>

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='urn:xmpp:sic:0'
    xmlns='urn:xmpp:sic:0'
    elementFormDefault='qualified'>

  <xs:element name='ip' type='xs:string'/>

</xs:schema>
  

Appendices

Appendix A: Document Information

Series: XEP
Number: 0279
Publisher: XMPP Standards Foundation
Status: Experimental
Type: Standards Track
Version: 0.1
Last Updated: 2010-03-05
Approving Body: XMPP Council
Dependencies: XMPP Core
Supersedes: None
Superseded By: None
Short Name: sic
Source Control: HTML  RSS

Appendix B: Author Information

Appendix C: Legal Notices

Appendix D: Relation to XMPP

The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 3920) and XMPP IM (RFC 3921) specifications contributed by the XMPP Standards Foundation to the Internet Standards Process, which is managed by the Internet Engineering Task Force in accordance with RFC 2026. Any protocol defined in this document has been developed outside the Internet Standards Process and is to be understood as an extension to XMPP rather than as an evolution, development, or modification of XMPP itself.

Appendix E: Discussion Venue

The primary venue for discussion of XMPP Extension Protocols is the <standards@xmpp.org> discussion list.

Discussion on other xmpp.org discussion lists might also be appropriate; see <http://xmpp.org/about/discuss.shtml> for a complete list.

Errata can be sent to <editor@xmpp.org>.

Appendix F: Requirements Conformance

The following requirements keywords as used in this document are to be interpreted as described in RFC 2119: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT"; "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY", "OPTIONAL".

Appendix G: Notes

Appendix H: Revision History

Note: Older versions of this specification might be available at http://xmpp.org/extensions/attic/

END