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(See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (April 30, 2008) is 5833 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-04) exists of draft-krishnan-mip6-firewall-vendor-03 ** Obsolete normative reference: RFC 3775 (Obsoleted by RFC 6275) Summary: 2 errors (**), 0 flaws (~~), 3 warnings (==), 7 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group S. Krishnan 3 Internet-Draft Ericsson 4 Intended status: Informational N. Steinleitner 5 Expires: November 1, 2008 University of Goettingen 6 Y. Qiu 7 Institute for Infocomm Research 8 G. Bajko 9 Nokia 10 April 30, 2008 12 Guidelines for firewall administrators regarding MIPv6 traffic 13 draft-krishnan-mip6-firewall-admin-04 15 Status of this Memo 17 By submitting this Internet-Draft, each author represents that any 18 applicable patent or other IPR claims of which he or she is aware 19 have been or will be disclosed, and any of which he or she becomes 20 aware will be disclosed, in accordance with Section 6 of BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF), its areas, and its working groups. Note that 24 other groups may also distribute working documents as Internet- 25 Drafts. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 The list of current Internet-Drafts can be accessed at 33 http://www.ietf.org/ietf/1id-abstracts.txt. 35 The list of Internet-Draft Shadow Directories can be accessed at 36 http://www.ietf.org/shadow.html. 38 This Internet-Draft will expire on November 1, 2008. 40 Copyright Notice 42 Copyright (C) The IETF Trust (2008). 44 Abstract 46 This document presents some recommendations for firewall 47 administrators to help them configure their existing firewalls in a 48 way that allows in certain deployment scenarios the Mobile IPv6 49 signaling and data messages to pass through. For other scenarios, 50 the support of additional mechanisms to create pinholes required for 51 MIPv6 will be necessary. This document assumes that the firewalls in 52 question include some kind of stateful packet filtering capability. 54 Table of Contents 56 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 57 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 3 59 4. Home Agent behind a firewall . . . . . . . . . . . . . . . . . 4 60 4.1. Signaling between the MN and the HA . . . . . . . . . . . 4 61 4.2. IKEv2 signaling between MN and HA for establishing SAs . . 5 62 5. Correspondent Node behind a firewall . . . . . . . . . . . . . 5 63 5.1. Route optimization signaling between MN and CN through 64 HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 65 5.2. Route optimization signaling between MN and CN . . . . . . 6 66 5.3. Binding Update from MN to CN . . . . . . . . . . . . . . . 7 67 5.4. Route Optimization data traffic from MN . . . . . . . . . 7 68 6. Mobile Node behind a firewall . . . . . . . . . . . . . . . . 7 69 6.1. Signaling between MN and HA . . . . . . . . . . . . . . . 8 70 6.2. Signaling between MN and CN . . . . . . . . . . . . . . . 8 71 6.3. IKEv2 signaling between MN and HA for establishing SAs . . 9 72 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 73 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 74 9. Security Considerations . . . . . . . . . . . . . . . . . . . 9 75 10. Normative References . . . . . . . . . . . . . . . . . . . . . 10 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 77 Intellectual Property and Copyright Statements . . . . . . . . . . 12 79 1. Requirements notation 81 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 82 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 83 document are to be interpreted as described in [RFC2119]. 85 2. Introduction 87 Network elements such as firewalls are an integral aspect of a 88 majority of IP networks today, given the state of security in the 89 Internet, threats, and vulnerabilities to data networks. MIPv6 90 [RFC3775] defines mobility support for IPv6 nodes. Firewalls will 91 interfere with the smooth operation of the MIPv6 protocol unless 92 specific steps are taken to allow Mobile IPv6 signaling and data 93 messages to pass through the firewall. The problems caused by 94 firewalls to Mobile IPv6 are documented in [RFC4487]. 96 This document presents some recommendations for firewall 97 administrators to help them configure their firewalls in a way that 98 allows the Mobile IPv6 signaling and data messages to pass through. 99 This document assumes that the firewalls in question include some 100 kind of stateful packet filtering capability. The static rules that 101 need to be configured are described in this document. In some 102 scenarios, the support of additional mechanisms to create pinholes 103 required for MIPv6 signalling and data traffic to pass through will 104 be necessary. A possible solution, describing the dynamic 105 capabilities needed for the firewalls to create pinholes based on 106 MIPv6 signalling traffic is described in a companion document 107 [MIP6FWVENDOR]. Other solutions may also be possible. 109 3. Abbreviations 111 This document uses the following abbreviations: 113 o CN: Correspondent Node 115 o CoA: Care of Address 117 o CoTI: Care of Test Init 119 o HA: Home Agent 121 o HoA: Home Address 123 o HoTI: Home Test Init 124 o HoT: Home Test 126 o MN: Mobile Node 128 o RO: Route Optimization 130 o RRT: Return Routability Test 132 4. Home Agent behind a firewall 134 This section presents the recommendations for configuring a firewall 135 that protects a home agent. 137 +----------------+ +---+ 138 | | | A | 139 | | +---+ 140 | +----+ | External 141 | | HA | +----+ MN 142 | +----+ | FW | +---+ 143 | Home Agent +----+ | B | 144 | of A | +---+ 145 | | External 146 | | Node 147 +----------------+ 148 Network protected 149 by a firewall 151 Figure 1: HA behind a firewall 153 For each type of traffic that needs to pass through this firewall, 154 recommendations are presented on how to identify that traffic. The 155 following types of traffic are considered 157 o Signaling between the MN and the HA 159 o IKEv2 signaling between MN and HA for establishing SAs 161 4.1. Signaling between the MN and the HA 163 The signaling between the MN and HA is protected using IPSec ESP. 164 These messages are critical to the MIPv6 protocol and if these 165 messages are discarded, Mobile IPv6 as specified today will cease to 166 work. In order to permit these messages through, the firewall has to 167 detect the messages using the following patterns. 169 Destination Address: Address of HA 170 Next Header: 50 (ESP) 171 Mobility Header Type: 5 (BU) 173 Destination Address: Address of HA 174 Next Header: 50 (ESP) 175 Mobility Header Type: 1 (HoTI) 177 This pattern will allow the BU messages from MNs to HA to pass 178 through. It will also allow the HoTI messages (related to route 179 optimization) between the MN and the HA to pass through. 181 4.2. IKEv2 signaling between MN and HA for establishing SAs 183 The MN and HA exchange IKEv2 signaling in order to establish the 184 security associations. The security associations so established will 185 later be used for securing the mobility signaling messages. Hence 186 these messages need to be permitted to pass through the firewalls. 187 The following pattern will detect these messages. 189 Destination Address: Address of HA 190 Transport Protocol: UDP 191 Destination UDP Port: 500 193 5. Correspondent Node behind a firewall 195 This section presents the recommendations for configuring a firewall 196 if a node behind it should be able to act as Mobile IPv6 CN. 198 +----------------+ +----+ 199 | | | HA | 200 | | +----+ 201 | | Home Agent 202 | +---+ +----+ of B 203 | |CN | | FW | 204 | | C | +----+ 205 | +---+ | +---+ 206 | | | B | 207 | | +---+ 208 +----------------+ External Mobile 209 Network protected Node 210 by a firewall 212 Figure 2: CN behind a firewall 214 For each type of traffic that needs to pass through this firewall, 215 recommendations are presented on how to identify that traffic. The 216 following types of traffic are considered 217 o Route optimization signaling between MN and CN through HA 219 o Route optimization signaling between MN and CN 221 o Binding Update from MN to CN 223 o Route Optimization data traffic from MN 225 5.1. Route optimization signaling between MN and CN through HA 227 Parts of the initial route optimization signaling has to pass through 228 the HA, namely the HoTI and the HoT messages. Without assistance, 229 the HoTI message from the HA to the CN is not able to traverse the 230 firewall. When only a few priviledged nodes (like servers) are 231 allowed to be contacted by outside nodes, then the following pattern 232 will allow the HoTI messages to reach these nodes: 234 Destination Address: CN Address 236 Mobility Header Type: 1 (HoTI) 238 where CN Address describes the address(es) of the priviledged 239 node(s). This pinhole allows the HoTI message from the HA to the CN 240 to traverse the firewall. The HoT message from the CN to the MN 241 through the HA can traverse the firewall without any assistance. 242 Hence no pinhole is required. 244 5.2. Route optimization signaling between MN and CN 246 Route Optimization allows direct communication of data packets 247 between the MN and a CN without tunnelling it back through the HA. 248 To get route optimization work, the MN has to send a CoTI message 249 directly to the CN, which response with a CoT message. However, a 250 stateful firewall would prevent the CoTI message to pass through as 251 there is no established state on the firewall. When only a few 252 priviledged nodes (like servers) are allowed to be contacted by 253 outside nodes, then the following pattern will allow the CoTI 254 messages to reach these nodes: 256 Destination Address: CN Address 258 Mobility Header Type: 2 (CoTI) 260 where CN Address describes the address(es) of the priviledged 261 node(s).The CoT message from the CN to the MN can traverse the 262 firewall without any assistance. Hence no pinhole is required. 264 5.3. Binding Update from MN to CN 266 After successfully performing the return routability procedure, the 267 MN sends the BU to the CN and expects the BA. Since this BU does not 268 match any previous installed pinhole rules, an additional pinhole 269 with the following format is required.When only a few priviledged 270 nodes (like servers) are allowed to be contacted by outside nodes, 271 then the following pattern will allow the BU messages to reach these 272 nodes: 274 Destination Address: CN Address 276 Mobility Header Type: 5 278 where CN Address describes the address(es) of the priviledged 279 node(s).This allows the BU to traverse the firewall and the BA can 280 pass the firewall without any assistance. Therefore, the Binding 281 Update sequence can be performed successfully. 283 5.4. Route Optimization data traffic from MN 285 Also the Route Optimization data traffic from MN directly to the CN 286 can not traverse the firewall without assistance. A dynamically 287 created pinhole such as the one specified in [MIP6FWVENDOR] will 288 allow this traffic to pass. 290 6. Mobile Node behind a firewall 292 This section presents the recommendations for configuring a firewall 293 that protects the network a mobile node visiting. 295 +----------------+ +----+ 296 | | | HA | 297 | | +----+ 298 | | Home Agent 299 | +---+ +----+ of A +---+ 300 | | A | | FW | | B | 301 | +---+ +----+ +---+ 302 |Internal | External 303 | MN | Node 304 | | 305 +----------------+ 306 Network protected 307 by a firewall 309 Figure 3: MN behind a firewall 311 For each type of traffic that needs to pass through this firewall, 312 recommendations are presented on how to identify that traffic. The 313 following types of traffic are considered 315 o Signaling between MN and HA 317 o Route Optimization Signaling between MN and CN 319 o IKEv2 signaling between MN and HA for establishing SAs 321 6.1. Signaling between MN and HA 323 As described in Section 4.1, the signaling between the MN and HA is 324 protected using IPSec ESP. Currently, a lot of firewalls are 325 configured to block the incoming ESP packets. Moreover, from the 326 view of the firewall, both source and destination addresses of these 327 messages from/to mobile node are variable. Fortunately, for a 328 stateful firewall, if the initial traffic is allowed through the 329 firewall, then the return traffic is also allowed. A mobile node is 330 always the initiator for the BU. Since MN's CoA is not able to be 331 known in advance, the firewall can use following patterns to permit 332 these messages through. 334 Source Address: Visited subnet prefix 336 Destination Address: Address of HA 337 Next Header: 50 (ESP) 338 Mobility Header Type: 1 (HoTI) 340 Source Address: Visited subnet prefix 342 Destination Address: Address of HA 343 Next Header: 50 (ESP) 344 Mobility Header Type: 5 (BU) 346 This pattern will allow the initial packets (e.g. BU from MNs to HA, 347 HoTI, etc.) to pass through the firewall. Then the return packets 348 (BA from HA to MN, HoT) is also able to pass through accordingly. 350 6.2. Signaling between MN and CN 352 Route Optimization allows direct communication of data packets 353 between the MN and a CN without tunneling it back through the HA. It 354 includes 3 pairs of messages: HoTI/HoT, CoTI/CoT and BU/BA. The 355 first pair can pass through the firewall using the pattern described 356 in section 5.1. Here we discuss CoTI/CoT and BU/BA messages. 357 Following pattern permits these messages through the firewall. 359 Source Address: Visited subnet prefix 360 Mobility Header Type: 2 (CoTI) 362 Source Address: Visited subnet prefix 363 Mobility Header Type: 5 (BU) 365 This pattern allows the initial messages (CoTI and BU) from the MN to 366 the CN pass through the firewall. The return messages (CoT and BA) 367 from the CN to the MN can also passes through the firewall 368 accordingly. 370 6.3. IKEv2 signaling between MN and HA for establishing SAs 372 The MN and HA exchange IKEv2 signaling in order to establish the 373 security associations. The security associations so established will 374 later be used for securing the mobility signaling messages. Due to 375 variable source/destination IP addresses and MN always as initiator, 376 the following pattern will let the negotiation pass. 378 Source Address: Visited subnet prefix 379 Transport Protocol: UDP 380 Destination UDP Port: 500 382 7. Acknowledgements 384 The authors would like to thank the following members of the MIPv6 385 firewall design team for contributing to this document: Hannes 386 Tschofenig, Hesham Soliman, Yaron Sheffer, and Vijay Devarapalli. 387 The authors would also like to thank William Ivancic, Ryuji Wakikawa, 388 Jari Arkko and Henrik Levkowetz for their thorough reviews of the 389 document and for providing comments to improve the quality of the 390 document. 392 8. IANA Considerations 394 This document does not require any IANA action. 396 9. Security Considerations 398 This document specifies recommendations for firewall administrators 399 to allow Mobile IPv6 traffic to pass through unhindered. Since some 400 of this traffic is encrypted it is not possible for firewalls to 401 discern whether it is safe or not. This document recommends a 402 liberal setting so that all legitimate traffic can pass. This means 403 that some malicious traffic may be permitted by these rules. These 404 rules may allow the initiation of Denial of Service attacks against 405 Mobile IPv6 capable nodes (the MNs, CNs and the HAs). 407 10. Normative References 409 [MIP6FWVENDOR] 410 Krishnan, S., Sheffer, Y., Steinleitner, N., and G. Bajko, 411 "Guidelines for firewall vendors regarding MIPv6 traffic", 412 draft-krishnan-mip6-firewall-vendor-03 (work in progress), 413 February 2008. 415 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 416 Requirement Levels", BCP 14, RFC 2119, March 1997. 418 [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support 419 in IPv6", RFC 3775, June 2004. 421 [RFC4487] Le, F., Faccin, S., Patil, B., and H. Tschofenig, "Mobile 422 IPv6 and Firewalls: Problem Statement", RFC 4487, 423 May 2006. 425 Authors' Addresses 427 Suresh Krishnan 428 Ericsson 429 8400 Decarie Blvd. 430 Town of Mount Royal, QC 431 Canada 433 Phone: +1 514 345 7900 x42871 434 Email: suresh.krishnan@ericsson.com 436 Niklas Steinleitner 437 University of Goettingen 438 Lotzestr. 16-18 439 Goettingen 440 Germany 442 Email: steinleitner@cs.uni-goettingen.de 443 Ying Qiu 444 Institute for Infocomm Research 445 21 Heng Mui Keng Terrace 446 Singapore 448 Phone: +65-6874-6742 449 Email: qiuying@i2r.a-star.edu.sg 451 Gabor Bajko 452 Nokia 454 Email: gabor.bajko@nokia.com 456 Full Copyright Statement 458 Copyright (C) The IETF Trust (2008). 460 This document is subject to the rights, licenses and restrictions 461 contained in BCP 78, and except as set forth therein, the authors 462 retain all their rights. 464 This document and the information contained herein are provided on an 465 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 466 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 467 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 468 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 469 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 470 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 472 Intellectual Property 474 The IETF takes no position regarding the validity or scope of any 475 Intellectual Property Rights or other rights that might be claimed to 476 pertain to the implementation or use of the technology described in 477 this document or the extent to which any license under such rights 478 might or might not be available; nor does it represent that it has 479 made any independent effort to identify any such rights. 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