Tuesday, March 5, 2019

Securing DNS with HTTPS

DNS is one of oldest protocol on the internet. It has been around ever since mail,  and has to be 35+ years old if I had to guess.

Over 35+ years ago, the internet was a much safer environment. So now DNS based attacks are still being used & and is a  big problem for some organizations.


With an unreliable protocol  such as UDP for transport,  you opening the door for spoof'd flood attacks to a victim network.









Next, UDP/TCP is support for  DNS over port 53 but no privacy. Anybody can peek at your traffic and analyze your traffic patterns  based on just  DNS query/response between client-server.







DNScrypt and DNSSEC was two attempts to secure DNS but these dropped from popularity. DNScurve was also an alternative. I wrote about this over 5 years ago.



Two current method that's available & that address both issues comes up as ;


DoH or DoT ( DNS Over HTTP or DNS Over   TLS)

Cloudflare / Google  and a few others have support for bothservices and these can  prevent and protect dns-data traffic. 

You can  make a simple  dns query to cloudflare over http for testing.



Both { DoH| DoT }  uses TLS for encryption , the over head would be much higher but at the benefit of security and protection from  spoof attacks. It's nice to know with cloudflare and GooG they only handle HTTPS and not HTTP.


A DNS-2-DoH  server could allow you to integrate these functions  with little impact to internal hosts as far as integration since DoH is  a simple HTTP.GET

example



For cloudflare;  you must set application type of JSON for proper response if not they will deliver a 4XX response. Goog does not enforce that requirement and ignore that header.


FWIW: Google seems to be much simpler for DoH queries





quad9 ( 9.9.9.9 ) has been supporting  DNSoverHTTP





NOTE:     I'm very disappointed  that OpenDNS   now { Umbrella };  does not support DoH or DoT and has no plan to do so !








NSE ( network security expert) and Route/Switching Engineer
kfelix  -----a----t---- socpuppets ---dot---com
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