6man Working Group Yu hua bing Internet-Draft Ruijie Networks, China Intended status: Standards Track Expiration: September 10, 2011 March 10, 2011 DisablePrivacy Flag of Prefix-information Option in the Router Advertisement draft-yhb-6man-ra-privacy-flag-02 Abstract The temporary addresses described by RFC4941 makes it more difficult for eavesdroppers and other information collectors to track the hosts,and it is necessary to the home networks,but in the enterprise networks, it is not necessary, and some network administrators want to disable the temporary addresses. This document tries to provide a solution to these network administrators,and they can specify whether the prefixes can be used to generate the temporary addresses. 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 http://datatracker.ietf.org/drafts/current/. 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." Copyright Notice Copyright (c) 2011 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 (http://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. Yu hua bing Expires September 2011 [Page 1] Internet-Draft DP Flag of Prefix-information Option March 2011 Table of Contents 1. Introduction ....................................................2 2. Protocol Specification ..........................................3 2.1. Modified Prefix-information Option .........................3 2.2. Router Specification .......................................3 2.3. Host Specification .........................................4 3. Security Consideration ..........................................4 4. Acknowledgements ................................................4 5. Change log ......................................................4 6. References ......................................................5 6.1. Normative References .......................................5 1. Introduction The temporary addresses described by RFC4941 makes it more difficult for eavesdroppers and other information collectors to track the hosts,and it is necessary to the home networks,but in the enterprise networks,it is not necessary, and some network administrators want to disable the temporary addresses. In some sites, the network administrators want to deploy stateless address autoconfiguration, and just permit the hardware-derived addresses to communicate with the Internet.They will do as follows: (1)Bind the MAC address and the hardware-derived address for each host on the access switches.Because the temporary addresses are variable, it is impossible to bind the MAC address and the temporary address. (2)Disable the temporary addresses on each host.Why?Because the temporary addresses may be preferred as the source of the outbound IPv6 traffic.Now it is difficult to disable the temporary addresses on all the hosts in the site,because: (2.1)The network administrator has to notify every one to disable the temporary adrresses.In the enterprise with thousands of employees, it is very difficult to ensure that every one will see the notice. (2.2)Many people are not familier with the host operation system, they don't know how to disable the temporary addresses. This document tries to provide a solution to these network administrators,and they can specify whether the prefixes can be used to generate the temporary addresses. The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this document, are to be interpreted as described in [RFC2119]. Yu hua bing Expires September 2011 [Page 2] Internet-Draft DP Flag of Prefix-information Option March 2011 2. Protocol Specification 2.1. Modified Prefix-information Option In order to implement the solution, a "DisablePrivacy" indication bit is added to the Reserved1 section of the prefix-information option in the router advertisement.Figure 1 shows the format of the modified prefix-information option,and "DP" stands for "DisablePrivacy". (The "R" bit was specified by [RFC3775], and "Rsvd1" stands for "Reserved1".) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Prefix Length |L|A|R|D| Rsvd1 | | | | | | | |P| | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Valid Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Preferred Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + Prefix + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Modified Prefix-information Option Format 2.2. Router Specification A router MUST allow the following autoconfiguration-related variable to be configured by system management for each interface: (1)DefEnablePrivacyOnIf This variable specifies the default value for each prefix on the interface.The default value of this variable is true. (2)PrefixEnablePrivacy The network administrator can explicitly specify whether the specific prefix can be used to generate the temporary addresses. If the variable DefEnablePrivacyOnIf is false and the variable PrefixEnablePrivacy for the prefix is not specified explicitly, or if the variable PrefixEnablePrivacy for the prefix is false,when the router sends the router advertisement,set the DisablePrivacy flag of the prefix-information option. Yu hua bing Expires September 2011 [Page 3] Internet-Draft DP Flag of Prefix-information Option March 2011 2.3. Host Specification A host MUST allow the following autoconfiguration-related variable to be configured by system management: EnablePrivacyAddr It means whether the host can generate the temporary addresses. When a host receives a valid router advertisement, for each Prefix -information option in the router advertisement,if the Managed flag is not set,the Autonomous flag is set,and the variable EnablePrivacyAddr is true,do as follows: (1)If the host doesn't recognize the DisablePrivacy flag,it SHOULD ignore this flag. (2)If the DisablePrivacy flag is not set,the host can use the prefix to generate a temporary address. (3)If the DisablePrivacy flag is set,and the prefix is same with the prefix of a temporary address configured by stateless autoconfiguration already in the list of addresses associated with the interface,do as follows: (3.1)If the temporary address is in preferred state,the host SHOULD change the state of the temporary address to deprecated. (3.2)If the temporary address is in tentative or duplicate state,the host SHOULD delete the temporary address at once. 3. Security Consideration It is possible that an attacker use the "DisablePrivacy" flag to force a host to deprecate it's active temporary addresses, but the threat is not so serious, so don't worry about it too much. If the privacy address is deprecated,the host can use the other IPv6 addresses, for example,the public address. 4. Acknowledgements The author would like to thank James Woodyatt,Ran Atkinson and other members for reviewing this document and suggesting changes. 5. Change log draft-yhb-6man-ra-privacy-flag-02: modify introduction, and add security consideration, 2011-03-08 draft-yhb-6man-ra-privacy-flag-01: The flag's name changed from Privacy to DisablePrivacy, 2011-03-05 draft-yhb-6man-ra-privacy-flag-00: original version, 2011-02-22 Yu hua bing Expires September 2011 [Page 4] Internet-Draft DP Flag of Prefix-information Option March 2011 6. References 6.1. Normative References [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, September 2007. [RFC4941] T. Narten,R. Draves and S. Krishnan, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 4941, September 2007. Authors' Addresses Yu hua bing Ruijie Networks Fuzhou Fujian China Email: yhb@ruijie.com.cn or yhb810501@gmail.com Yu hua bing Expires September 2011 [Page 5]