Network Working Group Y. Ma Internet-Draft Hitachi (China) Research & Intended status: Standards Track Development Corporation Expires: August 21, 2008 H. Deng China Mobile Y. Wu ZTE USA February 18, 2008 IPsec secured GRE tunnel demultiplexing problem statement draft-ma-softwire-ipsec-gre-demultiplexing-ps-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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. This Internet-Draft will expire on August 21, 2008. Copyright Notice Copyright (C) The IETF Trust (2008). Ma, et al. Expires August 21, 2008 [Page 1] Internet-Draft GRE demultiplexing for IPsec February 2008 Abstract This document describes the IPsec secured GRE based VPN demultiplexing problem statement. When two or more IPsec SAs are used to protect GRE encapsulated VPN network between the same pair of edge router, the current GRE based VPN does not support the edge router to demultiplex data for different IPsec SA. GRE key provides one solution to demultiplex the VPNs secured by IPsec. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem statement . . . . . . . . . . . . . . . . . . . . . . 4 2.1. softwire case . . . . . . . . . . . . . . . . . . . . . . 4 2.2. layer 3 VPN case . . . . . . . . . . . . . . . . . . . . . 5 2.3. Remote access compulsory VPN case . . . . . . . . . . . . 5 3. GRE key usage for IPsec secured VPN demultiplexing . . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 9 6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7. Normative References . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . . . 13 Ma, et al. Expires August 21, 2008 [Page 2] Internet-Draft GRE demultiplexing for IPsec February 2008 1. Introduction GRE is used to set up tunnel in many ways including the softwire mesh framework[softwire-mesh] and VPN network[RFC4023][RFC4110]. Also there are needs to protect GRE tunnel using IPsec for data plane of softwire mesh framework[softwire-sec-req] and l3vpn[l3vpn-ipsec]. In [l3vpn-ipsec] it is noted that a number of different MPLS VPNs might need to have traffic carried from a particular ingress PE to a particular egress PE through an IP/IPsec based transport network. It is thus natural to ask whether there should be one SA between the pair of PEs, or n SAs between the pair of PEs, where n is the number of VPNs. Existing IPsec implementation does not allow multiple SAs to be used for multiple VPNs, because the VPN multiplexing is done by MPLS inner label and both MPLS-in-IP and MPLS-in-GRE encapsulation do not provide a mechanism to demultiplex VPN traffic based on IPsec selector. However there exists scenarios where multiple IPsec SAs are needed to protect the GRE tunnel between the same pair of PEs. This documents descirbes several scenarios where multiple IPsec SAs are needed to protect GRE tunnels between the same pair. And currently there is no mechanism for IPsec to demultiplexing GRE encapsulated packets. And solution for IPsec SA to demultiplexing GRE encapsulated packets is proposed. Ma, et al. Expires August 21, 2008 [Page 3] Internet-Draft GRE demultiplexing for IPsec February 2008 2. Problem statement 2.1. softwire case Due to the address space limitation NAT is widely deployed for carrier's network. As shown in Fig. 1, several subnets are connected to the GW through the AR. The GRE tunnel is set up to encapsulate packets between AR and GW. If for example, subnet 1 and subnet 2 has the same private IP address subnet, the GW can not differentiate data from the two subnets by the IP address. In this case GRE key can be used to identify the tunnel from different subnets. If the carrier's network is connected to other networks by IPv6 only network, GRE will be used for data encapsulation. The GRE key used between AR and GW should be kept for the GW to demultiplex the packets. IPsec will be used to encrypt the GRE encapsulated packets. For different GRE tunnel, only one IPv6 IPsec SA will be used. This will cause potential security threats. Since if the IPsec is attacked, all the GRE tunnels will be affected. Also one advantage of GRE is that multicast can be supported by GRE. When multicast is taken into consideration, it is more desirable to provide different security level for different streams. Currently there is no mechanism to separate multicast and unicast traffic encapsulated in different GRE tunnels for IPsec SAs between the same pair of GWs. By providing multiplexing capability for IPsec SA to differentiate packets in different GRE tunnels between the same pair of GWs, such flexibility can be achieved. 10.0.0.x/24 +------+ | AR 1 |-----GRE key=1-------+ +------+ | 10.0.0.x/24 | IPv6 IPsec SA +------+ +------+_________________+------+ | AR 2 |-----GRE key=2-----| GW/ |=== GRE key=1 ===| | +------+ | AFBR | | AFBR | . | |=== GRE key=2 ===| | . | |-----------------| | . +------+ +------+ . | 10.1.0.x/24 | +------+ | | AR n |------GRE------------+ +------+ Ma, et al. Expires August 21, 2008 [Page 4] Internet-Draft GRE demultiplexing for IPsec February 2008 2.2. layer 3 VPN case As shown in Fig. 2, in [l3vpn-ipsec] scenario where there might need to be two (or more) SAs between the same pair of PEs is depicted. One IPsec SA can be used for data encryption and another one can be used for authentication but not encryption. This scenario actually describes a SA bundle case where ESP is applied first followed by AH protection on the same packet. It is different than applying different SAs to different packets based on IPsec selector criteria. VPN security requirements are described in [RFC4111]. Clearly, different VPN contexts have different security requirements, hence may require different security protections. Using one security association for all VPNs creates a greater risk if that security association is compromised. There is a clear need to apply different IPsec SAs to different VPN contexts. However, current IPsec implementation does not provide a mechanism that would allow demultiplexing VPN traffics into different SAs based on VPN contexts. Specifically, IPsec traffic selector is limited in VPN case. It is solely based on protocol type field, which is GRE for GRE based VPN and MPLS for MPLS based VPN. +--------+ +-------+ | VPN 1 |-------------+ | VPN 1 | +--------+ | +-------+ +--------+ +----+ IPsec tunnel +----+ | | VPN 2 |----------| PE |-------------------| PE |----------+ +--------+ | |=====GRE tunnel====| |----------+ . | |-------------------| | | . | | +----+ +-------+ . | | | VPN 2 | . | | IPsec tunnel +----+ +-------+ . | |-------------------| PE | +--------+ | |=====GRE tunnel====| | +-------+ | VPN n |----------| |-------------------| |--------| VPN n | +--------+ +----+ +----+ +-------+ 2.3. Remote access compulsory VPN case In remote access scenario, as shown in Fig. 3, different users access their home VPN gateways through an access network. The AR in access network establishes a compulsory tunnel to the user!_s home VPN gateway. The compulsory tunnel is traditionally L2TP [RFC2661], secured by IPsec [RFC3193]. However, all L2TP traffic, including user data and control signaling are protected by the same IPsec SA. Ma, et al. Expires August 21, 2008 [Page 5] Internet-Draft GRE demultiplexing for IPsec February 2008 If GRE tunnel can be used as compulsory tunnel mechanism, and different user traffics are multiplexed by GRE key. There could be a way to provide different security protection based on GRE key field. A GRE compulsory tunnel would also reduce the overhead of PPP/L2TP, both payload and signaling perspective, and provides a direct point- to-point tunnel for address configuration, such as DHCPv4 [RFC2131] and RS/RA [RFC4861]. A GRE compulsory tunnel could also serve as a generic tunnel for both layer2 and layer 3 traffic, as well as IP multicast. +--------+ | VPN 1 | | User 1 |-------------+ +--------+ | +--------+ +----+ IPsec tunnel +-------+ | VPN 1 | | | | | | User 2 |----------| AR |-------------------| VPN 1 | +--------+ | |=====GRE tunnels===| GW | . | |-------------------| | . | | +-------+ . | | . | | IPsec tunnel +-------+ . | |-------------------| VPN n | +--------+ | |=====GRE tunnels===| GW | | VPN n | | |-------------------| | | User m |----------| | +-------+ +--------+ +----+ Ma, et al. Expires August 21, 2008 [Page 6] Internet-Draft GRE demultiplexing for IPsec February 2008 3. GRE key usage for IPsec secured VPN demultiplexing If the packets of the VPNs need to be demulplexed by the IPsec, one way is to use GRE key to provide the demulplexing capability. The GRE tunnels are identified by GRE key. GRE key is then used by IPsec SA as the traffic selector. Although in [RFC4023] the usage of GRE key is not encouraged, it does not exclude the use of GRE key. However current IKE/IPsec implementation does not support GRE key as the traffic selector. Extensions for IKE/IPsec is needed to support GRE key. Ma, et al. Expires August 21, 2008 [Page 7] Internet-Draft GRE demultiplexing for IPsec February 2008 4. Security Considerations When multiple VPNs share an SA, the compromise of a key has a greater impact, and an attack on the security of one VPN may become an attack on the security of all the VPNs sharing the SA. So the idea of using multiple IPsec SAs improves the security for IPsec secured VPN. Ma, et al. Expires August 21, 2008 [Page 8] Internet-Draft GRE demultiplexing for IPsec February 2008 5. IANA Consideration This document defines no encodings, hence there are no IANA considerations. Ma, et al. Expires August 21, 2008 [Page 9] Internet-Draft GRE demultiplexing for IPsec February 2008 6. Conclusion This document describes a demulplexing problem statement where multiple IPsec SAs are used to protect data of different VPNs between the same CE/PE or PE/PE pair. GRE key is proposed to be used to demultiplex the data of different IPsec secured VPNs. Ma, et al. Expires August 21, 2008 [Page 10] Internet-Draft GRE demultiplexing for IPsec February 2008 7. Normative References [l3vpn-ipsec] Rosen, E., "Architecture for the Use of PE-PE IPsec Tunnels in BGP/MPLS IP VPNs", draft-ietf-l3vpn-ipsec-2547-05 (work in progress), August 2005. [softwire-mesh] Wu, J., Cui, Y., Li, X., Metz, C., Rosen, E., Barber, S., Mohapatra, P., and J. Scudder, "Softwire Mesh Framework", draft-ietf-softwire-mesh-framework-03 (work in progress), January 2008. [softwire-sec-req] Yamamoto, S., Williams, C., Parent, F., and H. Yokota, "Softwire Security Analysis and Requirements", draft-ietf-softwire-security-requirements-05 (work in progress), December 2007. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC2661] Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn, G., and B. Palter, "Layer Two Tunneling Protocol "L2TP"", RFC 2661, August 1999. [RFC3193] Patel, B., Aboba, B., Dixon, W., Zorn, G., and S. Booth, "Securing L2TP using IPsec", RFC 3193, November 2001. [RFC4023] Worster, T., Rekhter, Y., and E. Rosen, "Encapsulating MPLS in IP or Generic Routing Encapsulation (GRE)", RFC 4023, March 2005. [RFC4111] Fang, L., "Security Framework for Provider-Provisioned Virtual Private Networks (PPVPNs)", RFC 4111, July 2005. [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. Ma, et al. Expires August 21, 2008 [Page 11] Internet-Draft GRE demultiplexing for IPsec February 2008 Authors' Addresses Yuanchen Ma Hitachi (China) Research & Development Corporation 2, Kexueyuan Nanlu Haidian District, Beijing 100053 China Email: ycma610103@gmail.com Hui Deng China Mobile 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: denghui@chinamobile.com Yingzhe Wu ZTE USA 10105 Pacific Heights Blvd, Suite 250 San Diego, CA 92121 USA Email: yingzhe.wu@zteusa.com Ma, et al. Expires August 21, 2008 [Page 12] Internet-Draft GRE demultiplexing for IPsec February 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat 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 on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Ma, et al. Expires August 21, 2008 [Page 13]