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doh-proxy

A DNS-over-HTTPS Proxy

DNS Over HTTPS Proxy

Build Status PyPI version

A set of python 3 scripts that supports proxying DNS over HTTPS as specified in the IETF Draft draft-ietf-doh-dns-over-https.

DOH provides a way to run encrypted DNS over HTTPS, a protocol which can freely traverse firewalls when other encrypted mechanism may be blocked.

The project comes with a set of 4 tools:

See the CONTRIBUTING file for how to help out.

DOH Proxy was created during IETF Hackathon 100 as a proof-of-concept and is not used at Facebook.

You are welcome to use it, but be aware that support is limited and best-effort.

Installing

To install an already packaged version directly from PyPi:

$ pip3 install doh-proxy

Usage

doh-proxy

doh-proxy is a stand alone server answering DOH request. The proxy does not do DNS recursion itself and rather forward the query to a full-featured DNS recursive server or DNS caching server.

By running doh-proxy, you can get and end-to-end DOH solution with minimal setup.

$ sudo doh-proxy \
    --upstream-resolver=::1 \
    --certfile=./fullchain.pem \
    --keyfile=./privkey.pem

doh-httpproxy

doh-httpproxy is designed to be running behind a reverse proxy. In this setup a reverse proxy such as NGINX would be handling the HTTPS/HTTP2 requests from the DOH clients and will forward them to doh-httpproxy backends.

While this setup requires more upfront setup, it allows running DOH proxy unprivileged and on multiple cores.

$ sudo doh-httpproxy \
    --upstream-resolver=::1 \
    --port 8080 \
    --listen-address ::1

doh-stub

doh-stub is the piece of software that you would run on the clients. By providing a local DNS server, doh-stub will forward the DNS requests it receives to a DOH server using an encrypted link.

You can start a stub resolver with:

$ doh-stub \
    --listen-port 5553 \
    --listen-address ::1 \
    --domain foo.bar \
    --remote-address ::1

and query it.

$ dig @::1 -p 5553 example.com

doh-client

doh-client is just a test cli that can be used to quickly send a request to a DOH server and dump the returned answer.

$ doh-client  \
    --domain dns.dnsoverhttps.net \
    --qname sigfail.verteiltesysteme.net \
    --dnssec
id 37762
opcode QUERY
rcode SERVFAIL
flags QR RD RA
edns 0
eflags DO
payload 4096
;QUESTION
sigfail.verteiltesysteme.net. IN AAAA
;ANSWER
;AUTHORITY
;ADDITIONAL

$ doh-client  \
    --domain dns.dnsoverhttps.net \
    --qname sigok.verteiltesysteme.net \
    --dnssec
id 49772
opcode QUERY
rcode NOERROR
flags QR RD RA AD
edns 0
eflags DO
payload 4096
;QUESTION
sigok.verteiltesysteme.net. IN AAAA
;ANSWER
sigok.verteiltesysteme.net. 60 IN AAAA 2001:638:501:8efc::139
sigok.verteiltesysteme.net. 60 IN RRSIG AAAA 5 3 60 20180130030002 20171031030002 30665 verteiltesysteme.net. O7QgNZFBu3fULvBXwM39apv5nMehh51f mLOVEsC8qZUyxIbxo4eDLQt0JvPoPpFH 5TbWdlm/jxq5x2/Kjw7yUdpohhiNmdoD Op7Y+RyHbf676FoC5Zko9uOAB7Pp8ERz qiT0QPt1ec12bM0XKQigfp+2Hy9wUuSN QmAzXS2s75k=
;AUTHORITY
;ADDITIONAL

Development

Requirements

Building

DOH Proxy uses Python’setuptools to manage dependencies and build.

To install its dependencies:

$ python3 setup.py develop

To build:

$ python3 setup.py build

To run unittests:

$ python3 setup.py test

To run the linter:

$ python3 setup.py flake8

From within the root of the repository, you can test the proxy, stub and client respectively by using the following commands:

$ sudo PYTHONPATH=. ./dohproxy/proxy.py ...

$ PYTHONPATH=. ./dohproxy/httpproxy.py ...

$ PYTHONPATH=. ./dohproxy/stub.py ...

$ PYTHONPATH=. ./dohproxy/client.py ...

Example setups

In those examples, we will assume that we have the following setup:

This document will focus on the doh-proxy tools arguments and where they should be run. The specifics of configuring a DNS recursive resolver, reverse proxy are outside the scope of this document and are already intensively covered o the Internet.

Simple setup

On the server, we run the doh-proxy as root:

$ sudo doh-proxy \
    --certfile /etc/certs/dns.example.com/fullchain.pem \
    --keyfile /etc/certs/dns.example.com/privkey.pem \
    --upstream-resolver ::1

On the client

$ sudo doh-stub \
    --domain dns.example.com \
    --remote-address fdbe:7d77:b04f:a2ca::1 \
     --listen-address ::1

You can test it by running a dig on the client:

$ dig @::1 example.com

To start using it, update /etc/resolv.conf and change nameserver do be:

nameserver ::1

Behind a reverse proxy

In this setup, we will run a reverse proxy server that will take care of handling https request and forward them to a dns-httpproxy that runs on the same host.

Assuming we use nginx as our reverse proxy and 2 instances of doh-httpproxy, one listening on port 8080 and the other one on port 8081.

To run the doh-httpproxy processes:

$ doh-httpproxy --upstream-resolver ::1 --port 8080 --listen-address=::1
$ doh-httpproxy --upstream-resolver ::1 --port 8081 --listen-address=::1

And then the relevant Nginx config would look like:

upstream backend {
        server [::1]:8080;
        server [::1]:8081;
}

server {
        listen 443 ssl http2 default_server;
        listen [::]:443 ssl http2 default_server;

        server_name dns.example.com;

        location / {
              proxy_set_header Host $http_host;
              proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
              proxy_redirect off;
              proxy_buffering off;
              proxy_pass http://backend;
        }

        ssl_prefer_server_ciphers on;
        ssl_ciphers EECDH+CHACHA20:EECDH+AES128:RSA+AES128:EECDH+AES256:RSA+AES256:EECDH+3DES:RSA+3DES:!MD5;

        ssl_certificate /etc/certs/dns.example.com/fullchain.pem;
        ssl_certificate_key /etc/certs/dns.example.com/privkey.pem;
        ssl_dhparam /etc/nginx/ssl/dhparam.pem;
}

The client side is identical to the simple setup

License

DOH Proxy is BSD-licensed.