Evaggelos Balaskas - System Engineer

Using DNS over HTTPS aka DoH is fairly easy with the latest version of firefox. To use libredns is just a few settings in your browser, see here. In libredns’ site, there are also instructions for DNS over TLS aka DoT.

In this blog post, I am going to present how to use dnscrypt-proxy as a local dns proxy resolver using DoH the LibreDNS noAds (tracking) endpoint. With this setup, your entire operating system can use this endpoint for everything.

Disclaimer: This blog post is about dnscrypt-proxy version 2.

dnscrypt-proxy

dnscrypt-proxy 2 - A flexible DNS proxy, with support for modern encrypted DNS protocols such as DNSCrypt v2, DNS-over-HTTPS and Anonymized DNSCrypt.

Installation

sudo pacman -S dnscrypt-proxy

Verify Package

$ pacman -Qi dnscrypt-proxy

Name            : dnscrypt-proxy
Version         : 2.0.39-3
Description     : DNS proxy, supporting encrypted DNS protocols such as DNSCrypt v2 and DNS-over-HTTPS
Architecture    : x86_64
URL             : https://dnscrypt.info
Licenses        : custom:ISC
Groups          : None
Provides        : None
Depends On      : glibc
Optional Deps   : python-urllib3: for generate-domains-blacklist [installed]
Required By     : None
Optional For    : None
Conflicts With  : None
Replaces        : None
Installed Size  : 12.13 MiB
Packager        : David Runge <dvzrv@archlinux.org>
Build Date      : Sat 07 Mar 2020 08:10:14 PM EET
Install Date    : Fri 20 Mar 2020 10:46:56 PM EET
Install Reason  : Explicitly installed
Install Script  : Yes
Validated By    : Signature

Disable systemd-resolved

if necessary

$ ps -e fuwww | grep re[s]olv
systemd+     525  0.0  0.1  30944 21804 ?        Ss   10:00   0:01 /usr/lib/systemd/systemd-resolved

$ sudo systemctl stop systemd-resolved.service

$ sudo systemctl disable systemd-resolved.service
Removed /etc/systemd/system/multi-user.target.wants/systemd-resolved.service.
Removed /etc/systemd/system/dbus-org.freedesktop.resolve1.service.

Configuration

It is time to configure dnscrypt-proxy to use libredns

sudo vim /etc/dnscrypt-proxy/dnscrypt-proxy.toml

In the top of the file, there is a server_names section

  server_names = ['libredns-noads']

Resolv Conf

We can now change our resolv.conf to use our local IP address.

echo -e "nameserver 127.0.0.1noptions edns0 single-request-reopen" | sudo tee /etc/resolv.conf

$ cat /etc/resolv.conf

nameserver 127.0.0.1
options edns0 single-request-reopen

Systemd

start & enable dnscrypt service

sudo systemctl start dnscrypt-proxy.service

sudo systemctl enable dnscrypt-proxy.service

$ sudo ss -lntup '( sport = :domain )'

Netid  State   Recv-Q  Send-Q  Local Address:Port  Peer Address:Port  Process
udp    UNCONN  0       0       127.0.0.1:53       0.0.0.0:*          users:(("dnscrypt-proxy",pid=55795,fd=6))
tcp    LISTEN  0       4096    127.0.0.1:53       0.0.0.0:*          users:(("dnscrypt-proxy",pid=55795,fd=7))

Verify

$ dnscrypt-proxy -config /etc/dnscrypt-proxy/dnscrypt-proxy.toml -list
libredns-noads

$ dnscrypt-proxy -config /etc/dnscrypt-proxy/dnscrypt-proxy.toml -resolve balaskas.gr
Resolving [balaskas.gr]

Domain exists:  yes, 2 name servers found
Canonical name: balaskas.gr.
IP addresses:   158.255.214.14, 2a03:f80:49:158:255:214:14:80
TXT records:    v=spf1 ip4:158.255.214.14/31 ip6:2a03:f80:49:158:255:214:14:0/112 -all
Resolver IP:    116.202.176.26 (libredns.gr.)

Dig

asking our local dns (proxy)

dig @localhost balaskas.gr

; <<>> DiG 9.16.1 <<>> @localhost balaskas.gr
; (2 servers found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2449
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;balaskas.gr.                   IN      A

;; ANSWER SECTION:
balaskas.gr.            7167    IN      A       158.255.214.14

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Sat Mar 21 19:48:53 EET 2020
;; MSG SIZE  rcvd: 56

That’s it !

Yoursystem is now using LibreDNS DoH noads endpoint.

Manual Steps

If your operating system does not yet support dnscrypt-proxy-2 then:

Latest version

You can always download the latest version from github:

To view the files

curl -sLo - $(curl -sL https://api.github.com/repos/DNSCrypt/dnscrypt-proxy/releases/latest | jq -r '.assets[].browser_download_url | select( contains("linux_x86_64"))') | tar tzf -

linux-x86_64/
linux-x86_64/dnscrypt-proxy
linux-x86_64/LICENSE
linux-x86_64/example-cloaking-rules.txt
linux-x86_64/example-dnscrypt-proxy.toml
linux-x86_64/example-blacklist.txt
linux-x86_64/example-whitelist.txt
linux-x86_64/localhost.pem
linux-x86_64/example-ip-blacklist.txt
linux-x86_64/example-forwarding-rules.txt

To extrace the files

$ curl -sLo - $(curl -sL https://api.github.com/repos/DNSCrypt/dnscrypt-proxy/releases/latest | jq -r '.assets[].browser_download_url | select( contains("linux_x86_64"))') | tar xzf -

$ ls -l linux-x86_64/
total 9932
-rwxr-xr-x 1 ebal ebal 10117120 Μαρ  21 13:56 dnscrypt-proxy
-rw-r--r-- 1 ebal ebal      897 Μαρ  21 13:50 example-blacklist.txt
-rw-r--r-- 1 ebal ebal     1277 Μαρ  21 13:50 example-cloaking-rules.txt
-rw-r--r-- 1 ebal ebal    20965 Μαρ  21 13:50 example-dnscrypt-proxy.toml
-rw-r--r-- 1 ebal ebal      970 Μαρ  21 13:50 example-forwarding-rules.txt
-rw-r--r-- 1 ebal ebal      439 Μαρ  21 13:50 example-ip-blacklist.txt
-rw-r--r-- 1 ebal ebal      743 Μαρ  21 13:50 example-whitelist.txt
-rw-r--r-- 1 ebal ebal      823 Μαρ  21 13:50 LICENSE
-rw-r--r-- 1 ebal ebal     2807 Μαρ  21 13:50 localhost.pem

$ cd linux-x86_64/

Prepare the configuration

$ cp example-dnscrypt-proxy.toml dnscrypt-proxy.toml
$
$ vim dnscrypt-proxy.toml

In the top of the file, there is a server_names section

  server_names = ['libredns-noads']

$ ./dnscrypt-proxy -config dnscrypt-proxy.toml --list
[2020-03-21 19:27:20] [NOTICE] dnscrypt-proxy 2.0.40
[2020-03-21 19:27:20] [NOTICE] Network connectivity detected
[2020-03-21 19:27:22] [NOTICE] Source [public-resolvers] loaded
[2020-03-21 19:27:23] [NOTICE] Source [relays] loaded
libredns-noads

Run as root

$ sudo ./dnscrypt-proxy -config ./dnscrypt-proxy.toml
[sudo] password for ebal: *******

[2020-03-21 20:11:04] [NOTICE] dnscrypt-proxy 2.0.40
[2020-03-21 20:11:04] [NOTICE] Network connectivity detected
[2020-03-21 20:11:04] [NOTICE] Source [public-resolvers] loaded
[2020-03-21 20:11:04] [NOTICE] Source [relays] loaded
[2020-03-21 20:11:04] [NOTICE] Firefox workaround initialized
[2020-03-21 20:11:04] [NOTICE] Now listening to 127.0.0.1:53 [UDP]
[2020-03-21 20:11:04] [NOTICE] Now listening to 127.0.0.1:53 [TCP]
[2020-03-21 20:11:04] [NOTICE] [libredns-noads] OK (DoH) - rtt: 65ms
[2020-03-21 20:11:04] [NOTICE] Server with the lowest initial latency: libredns-noads (rtt: 65ms)
[2020-03-21 20:11:04] [NOTICE] dnscrypt-proxy is ready - live servers: 1

Check DNS

Interesting enough, first time is 250ms , second time is zero!

$ dig libredns.gr

; <<>> DiG 9.11.3-1ubuntu1.11-Ubuntu <<>> libredns.gr
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53609
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;libredns.gr.   IN  A

;; ANSWER SECTION:
libredns.gr.    2399  IN  A 116.202.176.26

;; Query time: 295 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Sat Mar 21 20:12:52 EET 2020
;; MSG SIZE  rcvd: 72

$ dig libredns.gr

; <<>> DiG 9.11.3-1ubuntu1.11-Ubuntu <<>> libredns.gr
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 31159
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;libredns.gr. IN  A

;; ANSWER SECTION:
libredns.gr.  2395  IN  A 116.202.176.26

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Sat Mar 21 20:12:56 EET 2020
;; MSG SIZE  rcvd: 72

That’s it