INTERNET DRAFT C. Huitema Microsoft Expires December 24, 2002 June 24, 2002 Unmanaged Networks Transition Scope Status of this memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. This document is an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract The NGTRANS working group is preparing the transition of the Internet from IPv4 to IPv6 and has devised a number of transition mechanisms. In order to evaluate the suitability of transition mechanisms, we need to define the environment or scope in which these mechanisms have to be used. One specific scope is the "unmanaged networks", which typically correspond to home networks or small office networks. 1 Introduction The NGTRANS working group is preparing the transition of the Internet from IPv4 to IPv6 and has devised a number of transition mechanisms. In order to evaluate the suitability of transition mechanisms, we need to define the environment or scope in which these mechanisms have to be used. One specific scope is the "unmanaged network". An unmanaged network consists of a (possibly large) number of nodes communicating via IP. All nodes are in the same administrative domain and are used typically by less than ten persons. Examples of unmanaged networks are home networks or small office networks. We present here the characteristics of unmanaged networks that are important for evaluating transition: their topology, the management constraints, the applications that must be supported. From these presentations, we define requirements that must be met in order to Huitema [Page 1] INTERNET DRAFT Unmanaged Networks Transition Scope June 24, 2002 support the desirable applications. 2 Topology The typical unmanaged network is composed of a single subnet, connected to the Internet through a single Internet Service Provider (ISP) connection. Several hosts are connected to the subnet: +------+ | Host +--+ +------+ | | +------+ | | Host +--+ +-------------- +------+ | | : +-----+ : +---------+ | | +--+ Gateway +------| ISP | Internet : +---------+ | | : +-----+ +------+ | | | Host +--+ +-------------- +------+ | | +------+ | | Host +--+ +------+ Between the subnet and the ISP access link is a gateway, which may or may not perform NAT and firewall function [RFC3022]. When the gateway performs a NAT function, the hosts are typically provided with "private addresses" [RFC1918]. A key point of this configuration is that the gateway is typically not "managed". In most cases, it is a simple "appliance", which incorporates some static policies. The access link between the unmanaged network and the ISP can be either static, i.e. a permanent connection, or dynamically established, i.e. a dial-up or ISDN connection. 2.1 Degenerated case of the single computer In a degenerate case, an unmanaged network can be constituted of a single host, directly connected to an ISP. 3 Management requirement An important characteristic of unmanaged networks is the absence of specialized personnel such as IT administrators. Configuration of the nodes must only be necessary at install time and must be so easy that most people are able to do it. Possible initial configuration could be: configuring a name of the node instead of the default one Huitema [Page 2] INTERNET DRAFT Unmanaged Networks Transition Scope June 24, 2002 and configuring whether the node should be accessible locally only or globally. After initial setup no further configuration is needed. The gateway(s) used should also be plug-and-play. 4 Applications Users may use or wish to use the unmanaged network services in four types of applications: local, client, servers and peer-to-peers. These applications may or may not run easily on today's network; in particular, when the gateway implement a NAT function, peer-to-peer and server applications tend to be severely impeded [RFC2993]. 4.1 Local applications Local applications are meant to only involve the hosts that are part of the unmanaged network. Typical examples are the sharing of file or printers. Local applications work effectively in IPv4 unmanaged networks, even when the gateway performs NAT or firewall function. In fact, firewall services at the gateway are often deemed desirable, as they isolate the local applications from interference by Internet users. 4.2 Client applications Client applications are those that involve a client on the unmanaged network and a server at a remote location. A typical example is accessing a web server from a client inside the managed network, or reading and sending e-mail with the help of a server outside the managed network. Local applications tend to work correctly in IPv4 unmanaged networks, even when the gateway performs NAT or firewall function: the translation and firewall functions are precisely designed to enable client applications. 4.3 Peer-to-peer applications Peer-to-peer applications are a restricted subset of the server applications, in which the services are only meant to be used by well identified peers outside the unmanaged network. Peer-to-peer applications typically use ad hoc naming systems, often derived from an "instant messaging" service. Many of these systems are proprietary; and example of standard system is the session initiation protocol (SIP) [RFC2543]. In these systems, the peers register their presence to a "rendezvous" service, using a name specific to the service; the case of SIP, they would use a SIP URL, of the form "sip:user@example.com"; a peer to peer session typically starts by an exchange of synchronization messages through the rendezvous service, during which the peers exchange the addresses that will be used for the session. Huitema [Page 3] INTERNET DRAFT Unmanaged Networks Transition Scope June 24, 2002 In many cases, the rendezvous service is provided by well connected servers, for example SIP servers; however, there are example of peer-to-peer systems in which the rendezvous service is effectively a distributed process, performed by the connected peers without the help of a central service. Examples of peer-to-peer applications would be a video-conference over IP, facilitated by a SIP server, a distributed game application, facilitated by a "game lobby", or file exchange systems such as "gnutella" that operate without servers. Peer-to-peer applications require direct communication between peers, and thus often don't work well in unmanaged IPv4 networks. The MIDCOM working group is developing solutions that would enable the real-time opening of "pin-holes" in the NAT or firewall, but the work is at its early stage and the results uncertain. Application developers often have to enlist the help of a "relay server", to effectively restructure the peer-to-peer connection in two back-to- back connections to a server. 4.4 Server applications Server applications involve running a server in the unmanaged network, for use by other parties outside the network. Examples would be running a web server or an e-mail server on one of the hosts inside the unmanaged network. It is difficult to deploy these servers in most unmanaged IPv4 networks as such deployment typically requires some special programming of the NAT or firewall. Deploying servers also require providing the servers with a stable DNS name, and associating a global IPv4 address with that name. 5 Requirement of an IPv6 unmanaged network As we transition to IPv6, we must meet the requirements of the various applications, which we can summarize in the following way: the applications that used to work well with IPv4 should continue working well during the transition; it should be possible to use IPv6 to deploy new applications that are currently hard to deploy in IPv4 networks. The application requirements are expressed in mostly three dimensions: connectivity, naming, and security. Connectivity issues include the provision of IPv6 addresses and their quality: do host need a global scope address, should this address be stable, or more precisely what should be the expected lifetime of the address. Naming issues include the management of names for the hosts: do hosts need a DNS-name, is inverse name resolution a requirement. 5.1 Requirements of local applications Local applications require local connectivity. They must continue Huitema [Page 4] INTERNET DRAFT Unmanaged Networks Transition Scope June 24, 2002 working even if the unmanaged network is isolated from the Internet. Local applications typically use ad hoc naming systems. Many of these systems are proprietary; and example of standard system is the service location protocol (SLP). The security of local applications is enhanced if these applications can be effectively isolated from the global Internet. 5.2 Requirements of client applications Client applications require connectivity. In an IPv6 network, we would expect the client to use a global IPv6 address, which will have to remain stable for the duration of the client-server session. Client applications typically use the domain name system to locate servers. In an IPv6 network, the client must be able to locate a DNS server. Many servers use "reverse DNS look-up" to locate the "friendly name" associated to the IP address of the client. In an IPv4 network, this IP address will typically be allocated by the Internet service provider to the gateway, and the corresponding PTR record will be maintained by the ISP. In most cases, these PTR records are perfunctory, derived in an algorithmic fashion from the IPv4 address; the main information that they contain is the domain name of the ISP. Whether or not an equivalent function should be provided in an IPv6 network is unclear. One of the main security issues with client applications is, maintaining the privacy of the client. Many gateways are designed to effectively hide the internal topology of the unmanaged network, presenting a single IPv4 address for many internal clients. In an IPv6 network, a similar degree of privacy will have to be maintained. 5.3 Requirements of peer-to-peer applications Peer-to-peer applications require connectivity and addressability: each peer must be able to contact the other peers. In an IPv6 network, we would expect the peers to use a global IPv6 address, which will have to remain stable for the duration of the peer-to- peer between client and server. Because they use ad hoc naming services, peer-to-peer applications often do not require support from the DNS. In particular, they do not require that the stations engaged in the peer-to-peer activity publish their address in a globally available service such as the DNS. There are multiple aspects to the security of peer-to-peer applications, many of which relate to the security of the rendezvous Huitema [Page 5] INTERNET DRAFT Unmanaged Networks Transition Scope June 24, 2002 system. If we assume that the peers have been able to safely exchange their IPv6 addresses, the main security requirement is the capability to safely exchange data between the peers, without interference by third parties. Peer-to-peer applications benefit greatly from "network effects", which may create a specific requirement during the transition to IPv6: the developers of these applications will be willing to consider IPv6 if they can be guaranteed that IPv6 packets will be able to quickly reach a majority of the Internet nodes. 5.4 Requirements of server applications Server applications require global connectivity, which in an IPv6 network implies global addresses. Server applications normally rely on the publication of the server's address in the DNS. This, in turns, requires that the server be provisioned with a "global DNS name". The DNS entries for the server will have to be updated, preferably in real time, if the server's address changes. In practice, updating the DNS is slow, which implies that server applications will have a better chance of being deployed if the IPv6 addresses remain stable for a long period. The security of server applications depends mostly on the correctness of the server, and also on the absence of collateral effects: many incidents occur when the opening of a server on the Internet inadvertently enables remote access to some other services on the same host. 6 Security Considerations Security considerations are discussed as part of the applications requirements. They include: - the guarantee that local applications are only used locally, - the protection of the privacy of clients - the requirement that peer-to-peer connections are only used by authorized peers. Given the absence of specialized personnel, these security requirements will have to be met without mandating specific configurations of the gateway or firewall to fit the needs of particular applications. 7 IANA Considerations This memo does not include any request to IANA. 8 Copyright Huitema [Page 6] INTERNET DRAFT Unmanaged Networks Transition Scope June 24, 2002 The following copyright notice is copied from RFC 2026 [Bradner, 1996], Section 10.4, and describes the applicable copyright for this document. Copyright (C) The Internet Society July 12, 2001. All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assignees. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 9 Intellectual Property The following notice is copied from RFC 2026 [Bradner, 1996], Section 10.4, and describes the position of the IETF concerning intellectual property claims made against this document. The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use other technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF Secretariat. Huitema [Page 7] INTERNET DRAFT Unmanaged Networks Transition Scope June 24, 2002 The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. 10 Acknowledgements A number of improvements on the initial draft of this memo were suggested by Ronald van der Pol. 11 References [RFC1918] Y. Rekhter, B. Moskowitz, D. Karrenberg, G. J. de Groot, E. Lear. "Address Allocation for Private Internets", RFC 1918, February 1996. [RFC2993] T. Hain. "Architectural Implications of NAT," RFC 2993, November 2000. [RFC3022] P. Srisuresh, K. Egevang. "Traditional IP Network Address Translator (Traditional NAT)", RFC 3022, January 2001. [RFC2543] M. Handley, H. Schulzrinne, E. Schooler, J. Rosenberg "SIP: Session Initiation Protocol", RFC 2543, March 1999. 12 Authors' Addresses Christian Huitema Microsoft Corporation One Microsoft Way Redmond, WA 98052-6399 Email: huitema@microsoft.com Huitema [Page 8] INTERNET DRAFT Unmanaged Networks Transition Scope June 24, 2002 Table of Contents: 1 Introduction .................................................... 1 2 Topology ........................................................ 2 2.1 Degenerated case of the single computer ....................... 2 3 Management requirement .......................................... 2 4 Applications .................................................... 3 4.1 Local applications ............................................ 3 4.2 Client applications ........................................... 3 4.3 Peer-to-peer applications ..................................... 3 4.4 Server applications ........................................... 4 5 Requirement of an IPv6 unmanaged network ........................ 4 5.1 Requirements of local applications ............................ 4 5.2 Requirements of client applications ........................... 5 5.3 Requirements of peer-to-peer applications ..................... 5 5.4 Requirements of server applications ........................... 6 6 Security Considerations ......................................... 6 7 IANA Considerations ............................................. 6 8 Copyright ....................................................... 6 9 Intellectual Property ........................................... 7 10 Acknowledgements ............................................... 8 11 References ..................................................... 8 12 Authors' Addresses ............................................. 8 Huitema [Page 9]