Network Working Group S. Krishnan Internet-Draft Ericsson Intended status: Informational June 28, 2007 Expires: December 30, 2007 Firewall Recommendations for MIPv6 draft-krishnan-mip6-firewall-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 December 30, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Krishnan Expires December 30, 2007 [Page 1] Internet-Draft MIPv6 Firewall BCP June 2007 Abstract This document presents some recommendations for firewall administrators to help them configure their firewalls in a way that allows Mobile IPv6 signaling and data messags to pass through. This document assumes that the firewalls in question include some kind of stateful packet filtering capability. Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Home Agent behind a firewall . . . . . . . . . . . . . . . . . 5 3.1. Signaling between the MN and the HA . . . . . . . . . . . 5 3.2. Route optimization signaling between MN and CN through HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3. IKEv2 signaling between MN and HA for establishing SAs . . 6 3.4. Data traffic from and to MN passing through the HA . . . . 6 4. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. Normative References . . . . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 Intellectual Property and Copyright Statements . . . . . . . . . . 11 Krishnan Expires December 30, 2007 [Page 2] Internet-Draft MIPv6 Firewall BCP June 2007 1. Requirements notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Krishnan Expires December 30, 2007 [Page 3] Internet-Draft MIPv6 Firewall BCP June 2007 2. Introduction Network elements such as firewalls are an integral aspect of a majority of IP networks today, given the state of security in the Internet, threats, and vulnerabilities to data networks. MIPv6 [RFC3775] defines mobility support for IPv6 nodes. Since firewalls are not aware of MIPv6 protocol details, they will probably interfere with the smooth operation of the protocol. The problems caused by firewalls to Mobile IPv6 are documented in [RFC4487] This document presents some recommendations for firewall administrators to help them configure their firewalls in a way that allows Mobile IPv6 signaling and data messags to pass through. This document assumes that the firewalls in question include some kind of stateful packet filtering capability. Krishnan Expires December 30, 2007 [Page 4] Internet-Draft MIPv6 Firewall BCP June 2007 3. Home Agent behind a firewall This section presents the recommendations for configuring a firewall that is protects a home agent. For each type of traffic that needs to pass through this firewall, recommendations are presented on how to identify that traffic. The following types of traffic are considered o Signaling between the MN and the HA o Route optimization signaling between MN and CN through HA o IKEv2 signaling between MN and HA for establishing SAs o Data traffic from and to MN passing through the HA 3.1. Signaling between the MN and the HA The signaling between the MN and HA is protected using IPSec ESP. These messages are encrypted and hence are not inspectable by firewalls. So the firewall either has to either permit all these messages or discard all of them. But if these messages are discarded, Mobile IPv6 as specified today will cease to work. In order to permit these messages through, the firewall has to detect the messages using the following pattern. Destination Address: Address of HA IP payload protocol number: 50 (ESP) This pattern will allow the BU messages from MNs to HA and BA messages from the HA to the MNs to pass through. It will also allow the HoTI and HoT messages (related to route optimization) between the MN and the HA to pass through. 3.2. Route optimization signaling between MN and CN through HA Route Optimization allows direct communication of data packets between the MN and a CN without tunneling it back through the HA. In order for route optimization to work, part of the initial signaling has to pass through the HA. The following pattern will allow these messages to pass through. Destination Address: HoA of MN Mobility Header Type: 3 This pattern allows the HoT message from the CN to the MN's HoA to pass through the firewall. The HoTI message from the MN to the CN through the HA usually passes through the firewall without any Krishnan Expires December 30, 2007 [Page 5] Internet-Draft MIPv6 Firewall BCP June 2007 problems. Hence no specific pattern is recommended. 3.3. IKEv2 signaling between MN and HA for establishing SAs The MN and HA exchange IKEv2 signaling in order to establish the security associations. The security associations so established will later be used for securing the mobility signaling messages. Hence these messages need to be permitted to pass through the firewalls. The following pattern will detect these messages. Destination Address: Address of HA Transport Protocol: UDP Destination UDP Port: 500 3.4. Data traffic from and to MN passing through the HA If a CN tries to initiate traffic to an MN, a stateful firewall would prevent these connection requests to pass through as there is no established state on the firewall. Since MNs do not usually provide services, this is not usually a problem. But if this is necessary to do, the pattern to look for is Destination Address: MN HoA Allowing this traffic might allow any kind of traffic, including malicious traffic, to pass through unfiltered to the MN. This might cause a Denial of Service at the MN. Krishnan Expires December 30, 2007 [Page 6] Internet-Draft MIPv6 Firewall BCP June 2007 4. Contributors This document is one of the deliverables of the MIPv6 firewall design. The following members of the team were involved in the creation of this document. Hannes Tschofenig Hannes.Tschofenig@gmx.net Gabor Bajko Gabor.Bajko@nokia.com Suresh Krishnan suresh.krishnan@ericsson.com Hesham Soliman solimanhs@gmail.com Yaron Sheffer yaronf@checkpoint.com Qiu Ying qiuying@i2r.a-star.edu.sg Ram Vishnu vishnu@motorola.com Niklas Steinleitner steinleitner@cs.uni-goettingen.de Vijay Devarapalli vijay.devarapalli@AzaireNet.com Krishnan Expires December 30, 2007 [Page 7] Internet-Draft MIPv6 Firewall BCP June 2007 5. Security Considerations This document specifies recommendations for firewall administrators to allow Mobile IPv6 traffic to pass through unhindered. Since some of this traffic is encrypted it is not possible for firewalls to discern whether it is safe or not. This document recommends a liberal setting so that all legitimate traffic can pass. This means that some malicious traffic may be permitted by these rules. These rules may allow the initiation of Denial of Service attacks against Mobile IPv6 capable nodes such as a home agent. Krishnan Expires December 30, 2007 [Page 8] Internet-Draft MIPv6 Firewall BCP June 2007 6. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [RFC4487] Le, F., Faccin, S., Patil, B., and H. Tschofenig, "Mobile IPv6 and Firewalls: Problem Statement", RFC 4487, May 2006. Krishnan Expires December 30, 2007 [Page 9] Internet-Draft MIPv6 Firewall BCP June 2007 Author's Address Suresh Krishnan Ericsson 8400 Decarie Blvd. Town of Mount Royal, QC Canada Phone: +1 514 345 7900 x42871 Email: suresh.krishnan@ericsson.com Krishnan Expires December 30, 2007 [Page 10] Internet-Draft MIPv6 Firewall BCP June 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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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). Krishnan Expires December 30, 2007 [Page 11]