XEP-0279: Server IP Check

1. Introduction¶

There are times when a client might want or need to discover what its external Internet Protocol (IP) address and port are, e.g. when gathering transport candidates for protocols such as SOCKS5 Bytestreams (XEP-0065) [1] or Jingle ICE-UDP Transport Method (XEP-0176) [2]. One way to do so is for the client to ask the XMPP server to which it has connected. This 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 and port returned by the server is different from the client's notion of its IP address and port 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.

<iq from='romeo@montague.lit/orchard'
    id='ik2s7159'
    type='get'>
  <address xmlns='urn:xmpp:sic:1'/>
</iq>

The server then returns an IQ-result containing an <address/> element containing an <ip/> element specifying the client's external IP address and, optionally, a <port/> element specifying the client's external port.

<iq id='ik2s7159'
    to='romeo@montague.lit/orchard'
    type='result'>
  <address xmlns='urn:xmpp:sic:1'>
    <ip>192.168.4.1</ip>
    <port>12345</port>
</iq>

Note that the IP address could be IPv4 or IPv6.

<iq id='ik2s7159'
    to='romeo@montague.lit/orchard'
    type='result'>
  <address xmlns='urn:xmpp:sic:1'>
    <ip>2001:db8::9:1</ip>
    <port>12345</port>
  </address>
</iq>

3. Determining Support¶

If an entity supports this protocol, it MUST report that by including a service discovery feature of "urn:xmpp:sic:1" in response to disco#info requests (see Protocol Namespaces regarding issuance of one or more permanent namespaces).

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

<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:1'/>
  </query>
</iq>

4. Security Considerations¶

XMPP Core [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:1'
    xmlns='urn:xmpp:sic:1'
    elementFormDefault='qualified'>

  <xs:element name='address' type='xs:string'/>
  <xs:element name='address'>
    <xs:complexType>
      <xs:sequence minOccurs='0'>
        <xs:element name='ip' maxOccurs='unbounded' type='xs:string'/>
        <xs:element name='port' maxOccurs='unbounded' type='xs:positiveInteger' use='optional'/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

</xs:schema>

8. Acknowledgements¶

Thanks to Joe Hildebrand for his feedback.

Appendices

Appendix A: Document Information¶

Series

XEP

Number

0279

Publisher

XMPP Standards Foundation

Status

Deferred

Type

Standards Track

Version

0.2

Last Updated

2013-04-17

Approving Body

XMPP Council

Dependencies

XMPP Core

Supersedes

None

Superseded By

None

Short Name

sic

Source Control

HTML

This document in other formats: XML  PDF

Appendix B: Author Information¶

Peter Saint-Andre

Email

stpeter@stpeter.im

JabberID

stpeter@jabber.org

URI

https://stpeter.im/

Diana Cionoiu

Email

diana@null.ro

JabberID

l-fy@jabber.null.ro

Thiago Camargo

Email

thiago@xmppjingle.com

JabberID

barata7@gmail.com

Appendix C: Legal Notices¶

Appendix D: Relation to XMPP¶

The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 6120) and XMPP IM (RFC 6121) 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 <https://xmpp.org/community/> 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 https://xmpp.org/extensions/attic/

1. Version 0.2 (2013-04-17)¶

   Modified XML format so server can return port as well as IP address; incremented protocol version from 0 to 1.

   psa
2. Version 0.1 (2010-03-05)¶

   Initial published version.

   psa
3. Version 0.0.2 (2009-03-10)¶

   Removed client inclusion of its IP address; added IPv6 example.

   psa
4. Version 0.0.1 (2009-03-10)¶

   First draft.

   psa

Appendix I: Bib(La)TeX Entry

@report{saint-andre2009sic,
  title = {Server IP Check},
  author = {Saint-Andre, Peter and Cionoiu, Diana and Camargo, Thiago},
  type = {XEP},
  number = {0279},
  version = {0.2},
  institution = {XMPP Standards Foundation},
  url = {https://xmpp.org/extensions/xep-0279.html},
  date = {2009-03-10/2013-04-17},
}

END