DNS Privacy Project

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LDNS (drill) 1.6.17

  • Source: ldns 1.6.17 source code available from this link to NLNet Labs: ldns-1.6.7
  • Patch: Grab and apply the patch to ldns-1.6.17 from out git repository. Also see the notes here.
  • Query: To query this with drill use: (the IP address is used here simply to stop the server name resolution falling back to TCP because your local resolver doesn't support DNS-over-TLS).

    • drill -t             @<serverIP>  <query name>    (to see TCP query)

    • drill -l -p1021 @<serverIP>  <query name>    (to see TLS query)

    • drill -C           @<serverIP>  <query name   (to see STARTTLS query)

    • drill -C -D      @<serverIP>  <query name>    (to do a DNSSEC lookup using STARTTLS)

Digit v1.4

  • Source: Grab the digit client DNS-over-TLS tool from the ISI website:
    http://www.isi.edu/ant/software/tdns/index.html
  • Query: Build digit with openssl:

    • create a file called queries containing a query name

    •  ./digit -f queries -r <serverIP> -V -t tcp     (to see TCP query)

    •  ./digit -f queries -r <serverIP> -V -t ssl      (to see DNS-over-TLS query) 

getdns v0.2

  • Source:  https://github.com/getdnsapi/getdns
  • Query: Use API directly (see below), or use with the wrapper script getdns_query (run 'make test' then getdns_query is found in the test directory):
    • getdns_query @<serverIP> -s -A -O  (Pipelined TCP queries)
    • getdns_query @<serverIP> -s -A -L  (Pipelined TLS queries)
    • getdns_query @<serverIP> -s -A -E  (Pipelined TLS queries with fallback to TCP)

getdns API

In the 0.2 release of getdns there is an experiment implementation of DNS-over-TLS. It is enabled by using one of the following options as the getdns_transport_t value in the getdns_context_set_dns_transport() method:

  • GETDNS_TRANSPORT_TLS_ONLY_KEEP_CONNECTIONS_OPEN
  • GETDNS_TRANSPORT_TLS_FIRST_AND_FALL_BACK_TO_TCP_KEEP_CONNECTIONS_OPEN

Notes:

  • This implementation is hard-coded to attempt to connect to the upstream server on port 1021 for TLS. 
  • These two transport values are not yet fully supported for recursive mode or for stub mode queries that use any of the DNSSEC extensions. See the table below for details.
  • No authentication is done in this implementation with regard to the certificate presented by the upstream server.
 RecursiveStub*Stub +dnssec extension**
TLS_ONLY
  • Not supported. 
  • Will error GETDNS_BAD_CONTEXT
Fully supported.
  • Supported but will not keep 
    connections open.
TLS_FIRST_AND_
FALL_BACK_TO_TCP
  • Will fallback to TCP without trying TLS 
  • Will not keep connections open
Fully supported.
  • Will fallback to TCP without trying TLS. 
  • Will not keep connections open.

* Uses TLS v1.2 only
**  Uses TLS 1.2 but will fallback to v1.1, v1

Future releases

  • STARTTLS will be available as an option in the next release.
  • Note that the transport options available in the API are under review. It is likely that the API will change to allow the user to specify a list of transports that should be used in order. This will better support flexible fallback mechanisms for TLS/STARTTLS/TCP. Additional transport options will also be added related to TCP/TLS connection management.

How to Decode TLS packets in Wireshark

If you want to decode the DNS packets in Wireshark (use 1.12.1 or later) to get support TLSv1.2

  • Obtain the server key file

  • Configure the key in wireshark in Edit->Preferences

    • open the protocol list in the right hand menu and select SSL from the list
    • Click on the RSA keys list 'Edit' box and then click on 'New' in the dialog that appears
      • Enter remote servers IP address and the port for TLS (1021), and 'http' or 'spdy' for the protocal (DNS is not yet available here).
      • Use the Key File selector to choose the key file you downloaded
    • Save this by hitting OK, OK and Apply.
    • Back in the main window use the Analyze->Decode as... option to choose to decode as SSL
    • Click on one of the packets labelled 'Application data' and you should see an additional tab appear in the Packet bytes view window of wireshark labelled "Decrypted SSL data".

 

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