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DNS Encryption and Its Controversies
sylph01
December 19, 2020
Technology
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DNS Encryption and Its Controversies
DNS暗号化とその論点 @ DNS温泉番外編 in 大阪
sylph01
December 19, 2020
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Transcript
DNS҉߸Խͱͦͷ sylph01 / Ryo Kajiwara @ DNSԹઘ൪֎ฤ in େࡕ, 2020/12/19
୭ʁ ֿݪ ཾ(sylph01) Twitter: @s01 ੜͷϓϩάϥϚ ҉߸ͱ͔Ͱ͖·͢ TLSΑΓ্ͷ DNS·ΔͰΘ͔ΒΜ
એ "DNSDNS Resolution" ͳΔຊΛॻ͍ٕͯ ज़ॻయ6(2019/4)Ͱ൦͠·ͨ͠ DNSʹର͢Δ߈ܸɺDNSϒϩοΩϯάɺ DNSSECɺDNS over TLS/HTTPS͋ͨΓ ͷɺDNSͷηΩϡϦςΟɾϓϥΠόγʔ
ʹؔΘΔτϐοΫΛѻ͍ͬͯ·͢ ࠓѻ͏DNS҉߸Խͷѻ͍ͬͯ·͢ ૿ิ൛Ͱ͋Δ"append mix"ΛBOOTHʹͯ ൦த
None
preface DNSSECͷͰͳ͍ɻ DNSSECॺ໊Ͱ͋ͬͯ҉߸ԽͰͳ͍ɻ DNS queryͷ౪ௌʹΑͬͯݸਓͷᅂɾࢥʹؔ͢ΔใΛऩू͢ Δ͜ͱ͕Մೳɺ͋Δ͍ϒϩοΩϯάΛߦ͏͜ͱ͕Մೳɻͦͷର ࡦͱͯ͠ͷDNS҉߸Խɻ DNS҉߸ԽΠϯλʔωοτ҉߸ԽͷϥετϫϯϚΠϧɻ
࣌ؒతʹද໘ͳͧΔͩ ͚Ͱ͢
Pervasive Monitoring is an Attack RFC 7258 2014/5
DNS Privacy Considerations RFC 7626 2015/8
None
DNS over TLS (DoT) RFC 7858 2016/5
DNS Queries over HTTPS (DoH) RFC 8484 2018/10
DoT vs DoH • DoTport 853Λ͏ɺDoHHTTPSͱಉ༷port 443Λ͏ • DoTport 853ͷϒϩοΩϯάͰՄೳ
• DoHport 443Λར༻͢ΔͷͰ௨ৗͷHTTPSϦΫΤετͱ۠ผ Ͱ͖ͳ͍ • ҰํͰΑ͘ΒΕ͍ͯΔDoHରԠαʔόʔͷIPϒϩοΩ ϯάΛߦ͑Մೳ
Oblivious DNS over HTTPS draft-pauly-dprive-oblivious-doh -00 @ 2020/10, -03 @
2020/12
None
None
DNS over QUIC https:/ /adguard.com/ja/blog/dns- over-quic.html
DNSCrypt, DNSCurve …ଘࡏ͢Δ͚ͲIETFͰඪ४Խ͞Εͯ ͳ͍ͷͰུ
None
: චऀ҉߸ԽਪਐدΓ Ͱ͢
DoT/DoH/ODoH ωοτϫʔΫཧऀʹ ͱͬͯ߹͕ѱ͍
ͦΕ ༷Ͱ͢
DNS҉߸Խsysadminʹ ߹͕ѱ͍ • ॾʑͷࣄ • DNSΛͬͯad-blocking, parental controlΛ͍ͨ͠ • DNSΛͬͯϗϞάϥϑ߈ܸtyposquatting͔ΒӴ͍ͨ͠
• nextdns.io ͱ͍͏αʔϏε͕ࣄ࣮ଘࡏ͢Δ • ͿͬͪΌ͚ ৗ࣌HTTPSԽE2EEsysadminʹ߹͕ѱ͍
DNS҉߸Խsysadminʹ ߹͕ѱ͍ • ͔͠͠DoT/DoH/ODoHωοτϫʔΫཧऀ͕ѱҙΛ͍࣋ͬͯ ΔέʔεΛఆͯ͠σβΠϯ͞Ε͍ͯΔ • ϓϩόΠμ͕σʔλΛऩू͍ͯ͠Δέʔε • ϓϩόΠμͱ݁ୗͯ͠ػ͕ؔσʔλΛऩू͢Δέʔε •
"Pervasive Monitoring is an Attack"
stub-recursive, recursive- authoritative͚ؒͩ҉߸Խ͢Δ͜ͱ Ͱ͖Δ͔ʁ • pervasive monitoringͷରࡦʹͳΔɺrecursive͕ѱҙͷ͋Δέʔ εҙຯͳ͍ • IPΞυϨεূ໌ॻͷऔಘͷϋʔυϧ͕ߴ͘ଓઌೝূ͕ࠔ
• ଓઌೝূΛͤͣ҉߸Խ͚ͩ͢Δ͜ͱΛ͢Εpervasive monitoringͷରࡦՄೳ
PKIΛͬͨTLSཱ͕ ͢ΔͷׂͱDNSͷ͓ ͔͛Έ͍ͨͳͱ͜Ζ͕ ͋Δ
DNSϒϩοΩϯάͱ ʮΠϯλʔωοτΛڊ େͳΠϯτϥωοτͱ Έͳͯ͠ཧ͍ͨ͠ʯ ͱ͍͏͜ͱʹ૬
DoT/DoHΠϯλʔωοτͷ தԝूݖԽΛଅ͢ • DoT/DoHαʔόʔͲ͏ͬͯબ͞ΕΔͷʁ • ৴༻Ͱ͖ΔDoT/DoHαʔόʔͱʁ • DoT/DoH৴༻ͷΛωοτϫʔΫࣄۀऀ͔ΒDoT/DoHαʔ όʔӡ༻ऀʹԡ͚͍ͯ͠Δ͚ͩͰͳ͍͔ʁ •
DoT/DoHαʔόʔࣄۀऀ͕ѱତͪͨ͠Βʁ
None
·ͱΊ • DNS queryͷ౪ௌ͕ࠔΔͷͰDNS҉߸Խ͕ੜ·ΕͨΑ • DNS over TLS (DoT), DNS
Queries over HTTPS (DoH)ͱ͍͏ͷ͕ओͳ ख๏ͩΑ • ҉߸Խ͞ΕΔͱsysadminʹ߹͕ѱ͍ɺ͚Ͳ༷ͩΑ • ৴༻ͬͯԿͩΖ͏
Questions? send to @s01 on Twitter