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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group S. Bortzmeyer 3 Internet-Draft AFNIC 4 Intended status: Informational October 26, 2014 5 Expires: April 29, 2015 7 DNS privacy considerations 8 draft-ietf-dprive-problem-statement-00 10 Abstract 12 This document describes the privacy issues associated with the use of 13 the DNS by Internet users. It is intended to be mostly an analysis 14 of the present situation, in the spirit of section 8 of [RFC6973] and 15 it does not prescribe solutions. 17 Discussions of the document should take place on the DPRIVE working 18 group mailing list [dprive]. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on April 29, 2015. 37 Copyright Notice 39 Copyright (c) 2014 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 56 2.1. The alleged public nature of DNS data . . . . . . . . . . 4 57 2.2. Data in the DNS request . . . . . . . . . . . . . . . . . 4 58 2.3. Cache snooping . . . . . . . . . . . . . . . . . . . . . 6 59 2.4. On the wire . . . . . . . . . . . . . . . . . . . . . . . 6 60 2.5. In the servers . . . . . . . . . . . . . . . . . . . . . 7 61 2.5.1. In the resolvers . . . . . . . . . . . . . . . . . . 7 62 2.5.2. In the authoritative name servers . . . . . . . . . . 8 63 2.5.3. Rogue servers . . . . . . . . . . . . . . . . . . . . 9 64 3. Actual "attacks" . . . . . . . . . . . . . . . . . . . . . . 9 65 4. Legalities . . . . . . . . . . . . . . . . . . . . . . . . . 9 66 5. Security considerations . . . . . . . . . . . . . . . . . . . 9 67 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 68 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 69 7.1. Normative References . . . . . . . . . . . . . . . . . . 10 70 7.2. Informative References . . . . . . . . . . . . . . . . . 10 71 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13 73 1. Introduction 75 The Domain Name System is specified in [RFC1034] and [RFC1035]. It 76 is one of the most important infrastructure components of the 77 Internet and one of the most often ignored or misunderstood. Almost 78 every activity on the Internet starts with a DNS query (and often 79 several). Its use has many privacy implications and we try to give 80 here a comprehensive and accurate list. 82 Let us begin with a simplified reminder of how the DNS works. A 83 client, the stub resolver, issues a DNS query to a server, the 84 resolver (also called caching resolver or full resolver or recursive 85 name server). Let's use the query "What are the AAAA records for 86 www.example.com?" as an example. AAAA is the qtype (Query type), and 87 www.example.com is the qname (Query Name). The resolver will first 88 query the root nameservers. In most cases, the root nameservers will 89 send a referral. In this example, the referral will be to .com 90 nameservers. The .com nameserver, in turn, will refer to the 91 example.com nameservers. The example.com nameserver will then return 92 the answer. The root name servers, the name servers of .com and 93 those of example.com are called authoritative name servers. It is 94 important, when analyzing the privacy issues, to remember that the 95 question asked to all these name servers is always the original 96 question, not a derived question. Unlike what many "DNS for dummies" 97 articles say, the question sent to the root name servers is "What are 98 the AAAA records for www.example.com?", not "What are the name 99 servers of .com?". By repeating the full question, instead of just 100 the relevant part of the question to the next in line, the DNS 101 provides more information than necessary to the nameserver. 103 Because the DNS uses caching heavily, not all questions are sent to 104 the authoritative name servers. If the stub resolver, a few seconds 105 later, asks to the resolver "What are the SRV records of _xmpp- 106 server._tcp.example.com?", the resolver will remember that it knows 107 the name servers of example.com and will just query them, bypassing 108 the root and .com. Because there is typically no caching in the stub 109 resolver, the resolver, unlike the authoritative servers, sees 110 everything. 112 Today, almost all DNS queries are sent over UDP. This has practical 113 consequences, when considering the encryption of this traffic: some 114 encryption solutions are only designed for TCP, not UDP. 116 It should be noted that DNS resolvers sometimes forward requests to 117 bigger machines, with a larger and more shared cache, the forwarders. 118 From the point of view of privacy, forwarders are like resolvers, 119 except that the caching in the resolver before them decreases the 120 amount of data they can see. 122 Another important point to keep in mind when analyzing the privacy 123 issues of DNS is the mix of many sort of DNS requests received by a 124 server. Let's assume the eavesdropper want to know which Web page is 125 visited by a user. For a typical Web page displayed by the user, 126 there are three sorts of DNS requests: 128 Primary request: this is the domain name that the user typed or 129 selected from a bookmark or choosed by clicking on an hyperklink. 130 Presumably, this is what is of interest for the eavesdropper. 132 Secondary requests: these are the requests performed by the user 133 agent (here, the Web browser) without any direct involvement or 134 knowledge of the user. For the Web, they are triggered by 135 included content, CSS sheets, JavaScript code, embedded images, 136 etc. In some cases, there can be dozens of domain names in a 137 single page. 139 Tertiary requests: these are the requests performed by the DNS 140 system itself. For instance, if the answer to a query is a 141 referral to a set of name servers, and the glue is not returned, 142 the resolver will have to do tertiary requests to turn name 143 servers' named into IP addresses. 145 For privacy-related terms, we will use here the terminology of 146 [RFC6973]. 148 2. Risks 150 This draft focuses mostly on the study of privacy risks for the end- 151 user (the one performing DNS requests). Privacy risks for the holder 152 of a zone (the risk that someone gets the data) are discussed in 153 [RFC5936]. Non-privacy risks (such as cache poisoning) are out of 154 scope. 156 2.1. The alleged public nature of DNS data 158 It has long been claimed that "the data in the DNS is public". While 159 this sentence makes sense for an Internet wide lookup system, there 160 are multiple facets to data and meta data that deserve a more 161 detailed look. First, access control lists and private name spaces 162 nonwithstanding, the DNS operates under the assumption that public 163 facing authoritative name servers will respond to "usual" DNS queries 164 for any zone they are authoritative for without further 165 authentication or authorization of the client (resolver). Due to the 166 lack of search capabilities, only a given qname will reveal the 167 resource records associated with that name (or that name's non 168 existence). In other words: one needs to know what to ask for, in 169 order to receive a response. The zone transfer qtype [RFC5936] is 170 often blocked or restricted to authenticated/authorized access to 171 enforce this difference (and maybe for other, more dubious reasons). 173 Another differentiation to be considered is between the DNS data 174 itself, and a particular transaction (i.e., a DNS name lookup). DNS 175 data and the results of a DNS query are public, within the boundaries 176 described above, and may not have any confidentiality requirements. 177 However, the same is not true of a single transaction or sequence of 178 transactions; that data is not/should not be public. A typical 179 example from outside the DNS world is: the Web site of Alcoholics 180 Anonymous is public; the fact that you visit it should not be. 182 2.2. Data in the DNS request 184 The DNS request includes many fields but two of them seem 185 particularly relevant for the privacy issues, the qname and the 186 source IP address. "source IP address" is used in a loose sense of 187 "source IP address + may be source port", because the port is also in 188 the request and can be used to sort out several users sharing an IP 189 address (CGN for instance). 191 The qname is the full name sent by the original user. It gives 192 information about what the user does ("What are the MX records of 193 example.net?" means he probably wants to send email to someone at 194 example.net, which may be a domain used by only a few persons and 195 therefore very revealing). Some qnames are more sensitive than 196 others. For instance, querying the A record of google-analytics.com 197 reveals very little (everybody visits Web sites which use Google 198 Analytics) but querying the A record of www.verybad.example where 199 verybad.example is the domain of an illegal or very offensive 200 organization may create more problems for the user. Another example 201 is when the qname embeds the software one uses. For instance, 202 _ldap._tcp.Default-First-Site-Name._sites.gc._msdcs.example.org. Or 203 some BitTorrent clients that query a SRV record for _bittorrent- 204 tracker._tcp.domain.example. 206 Another important thing about the privacy of the qname is the future 207 usages. Today, the lack of privacy is an obstacle to putting 208 potentially sensitive or personally identifiable data in the DNS. At 209 the moment your DNS traffic might reveal that you are doing email but 210 not who with. If your MUA starts looking up PGP keys in the DNS 211 [I-D.wouters-dane-openpgp] then privacy becomes a lot more important. 212 And email is just an example; there will be other really interesting 213 uses for a more privacy-friendly DNS. 215 For the communication between the stub resolver and the resolver, the 216 source IP address is the address of the user's machine. Therefore, 217 all the issues and warnings about collection of IP addresses apply 218 here. For the communication between the resolver and the 219 authoritative name servers, the source IP address has a different 220 meaning; it does not have the same status as the source address in a 221 HTTP connection. It is now the IP address of the resolver which, in 222 a way "hides" the real user. However, it does not always work. 223 Sometimes [I-D.vandergaast-edns-client-subnet] is used (see its 224 privacy analysis in [denis-edns-client-subnet]). Sometimes the end 225 user has a personal resolver on her machine. In that case, the IP 226 address is as sensitive as it is for HTTP. 228 A note about IP addresses: there is currently no IETF document which 229 describes in detail the privacy issues of IP addressing. In the mean 230 time, the discussion here is intended to include both IPv4 and IPv6 231 source addresses. For a number of reasons their assignment and 232 utilization characteristics are different, which may have 233 implications for details of information leakage associated with the 234 collection of source addresses. (For example, a specific IPv6 source 235 address seen on the public Internet is less likely than an IPv4 236 address to originate behind a CGN or other NAT.) However, for both 237 IPv4 and IPv6 addresses, it's important to note that source addresses 238 are propagated with queries and comprise metadata about the host, 239 user, or application that originated them. 241 2.3. Cache snooping 243 The content of resolvers can reveal data about the clients using it. 244 This information can sometimes be examined by sending DNS queries 245 with RD=0 to inspect cache content, particularly looking at the DNS 246 TTLs. Since this also is a reconnaissance technique for subsequent 247 cache poisoning attacks, some counter measures have already been 248 developed and deployed. 250 2.4. On the wire 252 DNS traffic can be seen by an eavesdropper like any other traffic. 253 It is typically not encrypted. (DNSSEC, specified in [RFC4033] 254 explicitely excludes confidentiality from its goals.) So, if an 255 initiator starts a HTTPS communication with a recipient, while the 256 HTTP traffic will be encrypted, the DNS exchange prior to it will not 257 be. When the other protocols will become more or more privacy-aware 258 and secured against surveillance, the DNS risks to become "the 259 weakest link" in privacy. 261 What also makes the DNS traffic different is that it may take a 262 different path than the communication between the initiator and the 263 recipient. For instance, an eavesdropper may be unable to tap the 264 wire between the initiator and the recipient but may have access to 265 the wire going to the resolver, or to the authoritative name servers. 267 The best place, from an eavesdropper's point of view, is clearly 268 between the stub resolvers and the resolvers, because he is not 269 limited by DNS caching. 271 The attack surface between the stub resolver and the rest of the 272 world can vary widely depending upon how the end user's computer is 273 configured. By order of increasing attack surface: 275 The resolver can be on the end user's computer. In (currently) a 276 small number of cases, individuals may choose to operate their own 277 DNS resolver on their local machine. In this case the attack surface 278 for the stub resolver to caching resolver connection is limited to 279 that single machine. 281 The resolver can be in the IAP (Internet Access Provider) premises. 282 For most residential users and potentially other networks the typical 283 case is for the end user's computer to be configured (typically 284 automatically through DHCP) with the addresses of the DNS resolver at 285 the IAP. The attack surface for on-the-wire attacks is therefore 286 from the end user system across the local network and across the IAP 287 network to the IAP's resolvers. 289 The resolver may also be at the local network edge. For many/most 290 enterprise networks and for some residential users the caching 291 resolver may exist on a server at the edge of the local network. In 292 this case the attack surface is the local network. Note that in 293 large enterprise networks the DNS resolver may not be located at the 294 edge of the local network but rather at the edge of the overall 295 enterprise network. In this case the enterprise network could be 296 thought of as similar to the IAP network referenced above. 298 The resolver can be a public DNS service. Some end users may be 299 configured to use public DNS resolvers such as those operated by 300 Google Public DNS or OpenDNS. The end user may have configured their 301 machine to use these DNS resolvers themselves - or their IAP may 302 choose to use the public DNS resolvers rather than operating their 303 own resolvers. In this case the attack surface is the entire public 304 Internet between the end user's connection and the public DNS 305 service. 307 2.5. In the servers 309 Using the terminology of [RFC6973], the DNS servers (resolvers and 310 authoritative servers) are enablers: they facilitate communication 311 between an initiator and a recipient without being directly in the 312 communications path. As a result, they are often forgotten in risk 313 analysis. But, to quote again [RFC6973], "Although [...] enablers 314 may not generally be considered as attackers, they may all pose 315 privacy threats (depending on the context) because they are able to 316 observe, collect, process, and transfer privacy-relevant data." In 317 [RFC6973] parlance, enablers become observers when they start 318 collecting data. 320 Many programs exist to collect and analyze DNS data at the servers. 321 From the "query log" of some programs like BIND, to tcpdump and more 322 sophisticated programs like PacketQ [packetq] and DNSmezzo 323 [dnsmezzo]. The organization managing the DNS server can use this 324 data itself or it can be part of a surveillance program like PRISM 325 [prism] and pass data to an outside attacker. 327 Sometimes, these data are kept for a long time and/or distributed to 328 third parties, for research purposes [ditl], for security analysis, 329 or for surveillance tasks. Also, there are observation points in the 330 network which gather DNS data and then make it accessible to third- 331 parties for research or security purposes ("passive DNS 332 [passive-dns]"). 334 2.5.1. In the resolvers 335 Resolvers see all the traffic since there is typically no caching 336 before them. They are, therefore, well situated to observe the 337 traffic. To summarize: your resolver knows a lot about you. The 338 resolver of a large IAP, or a large public resolver can collect data 339 from many users. You may get an idea of the data collected by 340 reading the privacy policy of a big public resolver [1]. 342 2.5.2. In the authoritative name servers 344 Unlike resolvers, authoritative name servers are limited by caching; 345 they see only a part of the requests. For aggregated statistics 346 ("What is the percentage of LOC queries?"), this is sufficient; but 347 it may prevent an observer from seeing everything. Still, the 348 authoritative name servers see a part of the traffic, and this subset 349 may be sufficient to violate some privacy expectations. 351 Also, the end user has typically some legal/contractual link with the 352 resolver (he has chosen the IAP, or he has chosen to use a given 353 public resolver), while he is often not even aware of the role of the 354 authoritative name servers and their observation abilities. 356 It is an interesting question whether the privacy issues are bigger 357 in the root or in a large TLD. The root sees the traffic for all the 358 TLDs (and the huge amount of traffic for non-existing TLD), but a 359 large TLD has less caching before it. 361 As noted before, using a local resolver or a resolver close to the 362 machine decreases the attack surface for an on-the-wire eavesdropper. 363 But it may decrease privacy against an observer located on an 364 authoritative name server. This authoritative name server will see 365 the IP address of the end client, instead of the address of a big 366 resolver shared by many users. A possible solution is to have a 367 local resolver and to forward the cache misses to a big resolver. 369 This "protection", when using a large resolver with many clients, is 370 no longer present if [I-D.vandergaast-edns-client-subnet] is used 371 because, in this case, the authoritative name server sees the 372 original IP address (or prefix, depending on the setup). 374 As of today, all the instances of one root name server, L-root, 375 receive together around 20,000 queries per second. While most of it 376 is junk (errors on the TLD name), it gives an idea of the amount of 377 big data which pours into name servers. 379 Many domains, including TLD, are partially hosted by third-party 380 servers, sometimes in a different country. The contracts between the 381 domain manager and these servers may or may not take privacy into 382 account. Whatever the contract, the third-party hoster may be honest 383 or not but, in any case, it will have to follow its local laws. It 384 may be surprising for an end-user that requests to a given ccTLD may 385 go to servers managed by organisations outside of the country. 387 2.5.3. Rogue servers 389 A rogue DHCP server can direct you to a rogue resolver. Most of the 390 times, it seems to be done to divert traffic, by providing lies for 391 some domain names. But it could be used just to capture the traffic 392 and gather information about you. Same thing for malwares like 393 DNSchanger[dnschanger] which changes the resolver in the machine's 394 configuration. 396 3. Actual "attacks" 398 A very quick examination of DNS traffic may lead to the false 399 conclusion that extracting the needle from the haystack is difficult. 400 "Interesting" primary DNS requests are mixed with useless (for the 401 eavesdropper) second and tertiary requests (see the terminology in 402 Section 1). But, in this time of "big data" processing, powerful 403 techniques now exist to get from the raw data to what you're actually 404 interested in. 406 Many research papers about malware detection use DNS traffic to 407 detect "abnormal" behaviour that can be traced back to the activity 408 of malware on infected machines. Yes, this research was done for the 409 good but, technically, it is a privacy attack and it demonstrates the 410 power of the observation of DNS traffic. See [dns-footprint], 411 [dagon-malware] and [darkreading-dns]. 413 Passive DNS systems [passive-dns] allow reconstruction of the data of 414 sometimes an entire zone. It is used for many reasons, some good, 415 some bad. It is an example of privacy issue even when no source IP 416 address is kept. 418 4. Legalities 420 To our knowledge, there are no specific privacy laws for DNS data. 421 Interpreting general privacy laws like [data-protection-directive] 422 (European Union) in the context of DNS traffic data is not an easy 423 task and it seems there is no court precedent here. 425 5. Security considerations 427 This document is entirely about security, more precisely privacy. A 428 document on requirments for DNS privacy is [I-D.hallambaker-dnse]. 429 Possible solutions to the issues described here are discussed in 430 [I-D.ietf-dnsop-qname-minimisation] (qname minimization), in 432 [I-D.bortzmeyer-dnsop-privacy-sol] (local caching resolvers, 433 gratuitous queries), [I-D.hzhwm-start-tls-for-dns] (encryption of 434 traffic), in [I-D.wijngaards-dnsop-confidentialdns] (encryption also) 435 or in many other documents (there are many proposals to encrypt the 436 DNS). Attempts have been made to encrypt the resource record data 437 [I-D.timms-encrypt-naptr]. 439 6. Acknowledgments 441 Thanks to Nathalie Boulvard and to the CENTR members for the original 442 work which leaded to this draft. Thanks to Ondrej Sury for the 443 interesting discussions. Thanks to Mohsen Souissi for proofreading 444 and to Warren Kumari for proofreading and many readability 445 improvements. Thanks to Dan York, Suzanne Woolf, Tony Finch, Peter 446 Koch and Frank Denis for good written contributions. 448 7. References 450 7.1. Normative References 452 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 453 STD 13, RFC 1034, November 1987. 455 [RFC1035] Mockapetris, P., "Domain names - implementation and 456 specification", STD 13, RFC 1035, November 1987. 458 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 459 Requirement Levels", BCP 14, RFC 2119, March 1997. 461 [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., 462 Morris, J., Hansen, M., and R. Smith, "Privacy 463 Considerations for Internet Protocols", RFC 6973, July 464 2013. 466 7.2. Informative References 468 [RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS 469 Specification", RFC 2181, July 1997. 471 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 472 Rose, "DNS Security Introduction and Requirements", RFC 473 4033, March 2005. 475 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 476 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 478 [RFC5936] Lewis, E. and A. Hoenes, "DNS Zone Transfer Protocol 479 (AXFR)", RFC 5936, June 2010. 481 [I-D.vandergaast-edns-client-subnet] 482 Contavalli, C., Gaast, W., Leach, S., and E. Lewis, 483 "Client Subnet in DNS Requests", draft-vandergaast-edns- 484 client-subnet-02 (work in progress), July 2013. 486 [I-D.bortzmeyer-dnsop-privacy-sol] 487 Bortzmeyer, S., "Possible solutions to DNS privacy 488 issues", draft-bortzmeyer-dnsop-privacy-sol-00 (work in 489 progress), December 2013. 491 [I-D.ietf-dnsop-qname-minimisation] 492 Bortzmeyer, S., "DNS query name minimisation to improve 493 privacy", draft-ietf-dnsop-qname-minimisation-00 (work in 494 progress), October 2014. 496 [I-D.wijngaards-dnsop-confidentialdns] 497 Wijngaards, W. and G. Wiley, "Confidential DNS", draft- 498 wijngaards-dnsop-confidentialdns-01 (work in progress), 499 March 2014. 501 [I-D.timms-encrypt-naptr] 502 Timms, B., Reid, J., and J. Schlyter, "IANA Registration 503 for Encrypted ENUM", draft-timms-encrypt-naptr-01 (work in 504 progress), July 2008. 506 [I-D.hzhwm-start-tls-for-dns] 507 Zi, Z., Zhu, L., Heidemann, J., Mankin, A., and D. 508 Wessels, "Starting TLS over DNS", draft-hzhwm-start-tls- 509 for-dns-00 (work in progress), February 2014. 511 [I-D.hallambaker-dnse] 512 Hallam-Baker, P., "DNS Privacy and Censorship: Use Cases 513 and Requirements.", draft-hallambaker-dnse-01 (work in 514 progress), May 2014. 516 [I-D.wouters-dane-openpgp] 517 Wouters, P., "Using DANE to Associate OpenPGP public keys 518 with email addresses", draft-wouters-dane-openpgp-02 (work 519 in progress), February 2014. 521 [dprive] IETF, ., "The DPRIVE working group", March 2014, 522 . 524 [dnsop] IETF, ., "The DNSOP working group", October 2013, 525 . 527 [denis-edns-client-subnet] 528 Denis, F., "Security and privacy issues of edns-client- 529 subnet", August 2013, . 532 [dagon-malware] 533 Dagon, D., "Corrupted DNS Resolution Paths: The Rise of a 534 Malicious Resolution Authority", 2007, . 538 [dns-footprint] 539 Stoner, E., "DNS footprint of malware", October 2010, 540 . 543 [darkreading-dns] 544 Lemos, R., "Got Malware? Three Signs Revealed In DNS 545 Traffic", May 2013, . 548 [dnschanger] 549 Wikipedia, ., "DNSchanger", November 2011, 550 . 552 [dnscrypt] 553 Denis, F., "DNSCrypt", , . 555 [dnscurve] 556 Bernstein, D., "DNScurve", , . 558 [packetq] Dot SE, ., "PacketQ, a simple tool to make SQL-queries 559 against PCAP-files", 2011, . 562 [dnsmezzo] 563 Bortzmeyer, S., "DNSmezzo", 2009, 564 . 566 [prism] NSA, ., "PRISM", 2007, . 569 [crime] Rizzo, J. and T. Dong, "The CRIME attack against TLS", 570 2012, 571 . 573 [ditl] CAIDA, ., "A Day in the Life of the Internet (DITL)", 574 2002, . 576 [data-protection-directive] 577 Europe, ., "European directive 95/46/EC on the protection 578 of individuals with regard to the processing of personal 579 data and on the free movement of such data", November 580 1995, . 583 [passive-dns] 584 Weimer, F., "Passive DNS Replication", April 2005, 585 . 587 [tor-leak] 588 Tor, ., "DNS leaks in Tor", 2013, . 593 Author's Address 595 Stephane Bortzmeyer 596 AFNIC 597 1, rue Stephenson 598 Montigny-le-Bretonneux 78180 599 France 601 Phone: +33 1 39 30 83 46 602 Email: bortzmeyer+ietf@nic.fr 603 URI: http://www.afnic.fr/