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Its DNS Jim, but not as we know it! Sara Dickinson - PowerPoint PPT Presentation

Sep 07, 2022 •508 likes •1.13k views

Its DNS Jim, but not as we know it! Sara Dickinson sara@sinodun.com UKNOF 41 Its DNS Jim, but not as we know it! Stub to recursive What this talk will cover Overview : Summarise the most recent evolutions in how end-device DNS

  1. It’s DNS Jim, but not as we know it! Sara Dickinson sara@sinodun.com UKNOF 41 It’s DNS Jim, but not as we know it!

  2. Stub to recursive What this talk will cover Overview : Summarise the most recent evolutions in how end-device DNS resolution is being done (~past 5 years) New IETF standards: Encrypted transports for DNS (TLS & HTTPS) • Deployment Status : Clients and resolver services for encrypted DNS • DNS resolution directly from applications: Browsers • DNS resolution to third party providers: Implications for operators • UKNOF 41 It’s DNS Jim, but not as we know it! 2

  3. My Background Co-founder of Sinodun IT - small UK based consultancy • Focussed on DNS, DNSSEC and DNS Privacy • R&D, Open source dev, Standards dev • DNS-over-TLS: involved in standards dev, implementation and • deployment (we contribute to dnsprivacy.org). DNS-over-HTTPS: Not directly involved, no links to browser vendors • UKNOF 41 It’s DNS Jim, but not as we know it! 3

  4. My Background Co-founder of Sinodun IT - small UK based consultancy • Focussed on DNS, DNSSEC and DNS Privacy • R&D, Open source dev, Standards dev • DNS-over-TLS: involved in standards dev, implementation and • deployment (we contribute to dnsprivacy.org). DNS-over-HTTPS: Not directly involved, no links to browser vendors • Goal today is to bring awareness to this audience of fast moving changes: The good, the bad and the ugly…. UKNOF 41 It’s DNS Jim, but not as we know it! 3

  5. 
 The DNS is showing its age • Nov 1987 - RFC1034 and RFC1035 published! 
 No Security or Privacy in the original design! 1987 2018 UKNOF 41 It’s DNS Jim, but not as we know it! 4

  6. DNS-over-TLS (DoT) Snowdon Revelations 2014 2013 2016 1987 2012 2018 UKNOF 41 It’s DNS Jim, but not as we know it! 5

  7. DNS-over-TLS (DoT) RFC7258: Pervasive Monitoring is an attack Snowdon Revelations 2014 2013 2016 1987 2012 2018 UKNOF 41 It’s DNS Jim, but not as we know it! 5

  8. DNS-over-TLS (DoT) RFC7258: Goals: DPRIVE WG Pervasive Monitoring 1) Encrypt Stub-Rec DNS formed is an attack 2) Think about Rec-Auth? Snowdon Revelations 2014 2013 2016 1987 2012 2018 UKNOF 41 It’s DNS Jim, but not as we know it! 5

  9. DNS-over-TLS (DoT) RFC7258: Goals: DPRIVE WG Pervasive Monitoring 1) Encrypt Stub-Rec DNS formed is an attack 2) Think about Rec-Auth? RFC7766: DNS-over-TCP Snowdon Revelations 2014 2013 2016 1987 2012 2018 UKNOF 41 It’s DNS Jim, but not as we know it! 5

  10. DNS-over-TLS (DoT) RFC7258: Goals: DPRIVE WG Pervasive Monitoring 1) Encrypt Stub-Rec DNS formed is an attack 2) Think about Rec-Auth? RFC7858: RFC7766: DNS-over-TLS DNS-over-TCP Snowdon Port 853 Revelations 2014 2013 2016 1987 2012 2018 UKNOF 41 It’s DNS Jim, but not as we know it! 5

  11. DNS-over-TLS (DoT) Status Date Event Implementations : 2015 - 2018 Clients: Android Pie, systemd, Stubby Servers: Unbound, Knot resolver, dnsdist, (BIND) 2015 - now Set of 20 test DoT servers Nov 2017 Quad9 (9.9.9.9) offer DoT Mar 2018 Cloudflare launch 1.1.1.1 with DoT UKNOF 41 It’s DNS Jim, but not as we know it! 6

  12. DNS-over-TLS (DoT) Status Date Event Implementations : System stub resolvers: 2015 - 2018 Need native Windows Clients: Android Pie, systemd, Stubby & macOS/iOS support Servers: Unbound, Knot resolver, dnsdist, (BIND) 2015 - now Set of 20 test DoT servers Nov 2017 Quad9 (9.9.9.9) offer DoT Mar 2018 Cloudflare launch 1.1.1.1 with DoT UKNOF 41 It’s DNS Jim, but not as we know it! 6

  13. DNS-over-TLS (DoT) Status Date Event Implementations : System stub resolvers: 2015 - 2018 Need native Windows Clients: Android Pie, systemd, Stubby & macOS/iOS support Servers: Unbound, Knot resolver, dnsdist, (BIND) 2015 - now Set of 20 test DoT servers Easy to run a DoT server Nov 2017 Quad9 (9.9.9.9) offer DoT Mar 2018 Cloudflare launch 1.1.1.1 with DoT UKNOF 41 It’s DNS Jim, but not as we know it! 6

  14. Encrypted DNS: the good… Defeats passive surveillance • Server authentication if a name is manually configured 
 • (PKIX or DANE - RFC8310) Prevents redirects, can’t intercept DNS queries • Increases ‘trust’ in service (DNSSEC, filtering…) • Data integrity of transport - can’t inject spoofed responses • UKNOF 41 It’s DNS Jim, but not as we know it! 7

  15. Encrypted DNS: the good… Opportunistic DoT : just need IP address Defeats passive surveillance • (Android Pie default) Server authentication if a name is manually configured 
 • (PKIX or DANE - RFC8310) Prevents redirects, can’t intercept DNS queries • Increases ‘trust’ in service (DNSSEC, filtering…) • Data integrity of transport - can’t inject spoofed responses • UKNOF 41 It’s DNS Jim, but not as we know it! 7

  16. Encrypted DNS: the good… Opportunistic DoT : just need IP address Defeats passive surveillance • (Android Pie default) Server authentication if a name is manually configured 
 • (PKIX or DANE - RFC8310) Prevents redirects, can’t intercept DNS queries • Strict DoT : need a name too Increases ‘trust’ in service (DNSSEC, filtering…) • Data integrity of transport - can’t inject spoofed responses • UKNOF 41 It’s DNS Jim, but not as we know it! 7

  17. Encrypted DNS: the bad & ugly… SNI still leaks (but not for long! draft-rescorla-tls-esni) • A dedicated port (853) can be blocked (443 fallback) • Resolver still sees all the traffic (who do you ‘trust’?) • If using a resolver NOT on the local network (not available) • Breaks Split horizon DNS (fallback possible), 
 • leaks internal names. Similar to e.g. using 8.8.8.8 but…. UKNOF 41 It’s DNS Jim, but not as we know it! 8

  18. Encrypted DNS: the bad & ugly… SNI still leaks (but not for long! draft-rescorla-tls-esni) • A dedicated port (853) can be blocked (443 fallback) • Resolver still sees all the traffic (who do you ‘trust’?) • If using a resolver NOT on the local network (not available) • Breaks Split horizon DNS (fallback possible), 
 • leaks internal names. Similar to e.g. using 8.8.8.8 but…. Encrypted traffic bypasses local monitoring & security policies UKNOF 41 It’s DNS Jim, but not as we know it! 8

  19. Encrypted DNS: the bad & ugly… SNI still leaks (but not for long! draft-rescorla-tls-esni) • A dedicated port (853) can be blocked (443 fallback) • Resolver still sees all the traffic (who do you ‘trust’?) • If using a resolver NOT on the local network (not available) • Breaks Split horizon DNS (fallback possible), 
 • leaks internal names. Similar to e.g. using 8.8.8.8 but…. Encrypted traffic bypasses local For DoT, seen as short term or rare… monitoring & security policies UKNOF 41 It’s DNS Jim, but not as we know it! 8

  20. UKNOF 41 It’s DNS Jim, but not as we know it! 9

  21. …..to their own chosen cloud resolver service! UKNOF 41 It’s DNS Jim, but not as we know it! 9

  22. DNS-over-HTTPS (DoH) IETF 98 Jul May Sep Oct 2017 2017 2017 2017 March Aug 2017 2018 1987 UKNOF 41 It’s DNS Jim, but not as we know it! 10

  23. DNS-over-HTTPS (DoH) First DoH draft published 
 (query init) IETF 98 Jul May Sep Oct 2017 2017 2017 2017 March Aug 2017 2018 1987 UKNOF 41 It’s DNS Jim, but not as we know it! 10

  24. DNS-over-HTTPS (DoH) Goals: “This working group will DoH WG 
 standardize encodings for DNS queries and responses formed that are suitable for use in HTTPS. ” First DoH draft published 
 (query init) IETF 98 Jul May Sep Oct 2017 2017 2017 2017 March Aug 2017 2018 1987 UKNOF 41 It’s DNS Jim, but not as we know it! 10

  25. DNS-over-HTTPS (DoH) Goals: “This working group will DoH WG 
 standardize encodings for DNS queries and responses formed that are suitable for use in HTTPS. ” First DoH draft published 
 (query init) DoH draft adopted IETF 98 Jul May Sep Oct 2017 2017 2017 2017 March Aug 2017 2018 1987 UKNOF 41 It’s DNS Jim, but not as we know it! 10

  26. DNS-over-HTTPS (DoH) Goals: “This working group will DoH WG 
 standardize encodings for DNS queries and responses formed that are suitable for use in HTTPS. ” First DoH draft published 
 (query init) DoH draft Submitted to adopted IESG IETF 98 Jul May Sep Oct 2017 2017 2017 2017 March Aug 2017 2018 1987 UKNOF 41 It’s DNS Jim, but not as we know it! 10

  27. DNS-over-HTTPS (DoH) Goals: “This working group will DoH WG 
 standardize encodings for DNS queries and responses formed that are suitable for use in HTTPS. ” First DoH draft published 
 (query init) DoH draft Submitted to adopted IESG Approved IETF 98 Jul May Sep Oct 2017 2017 2017 2017 March Aug 2017 2018 1987 UKNOF 41 It’s DNS Jim, but not as we know it! 10

  28. DNS-over-HTTPS (DoH) Goals: “This working group will DoH WG 
 standardize encodings for DNS queries and responses formed that are suitable for use in HTTPS. ” First DoH draft published 
 (query init) DoH draft Submitted to adopted IESG Approved IETF 98 Jul May Sep Oct FAST! 2017 2017 2017 2017 March Aug 2017 2018 1987 UKNOF 41 It’s DNS Jim, but not as we know it! 10

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