NAME

fdns - Firejail DNS over HTTPS/TLS proxy

SYNOPSIS

Start the server (root user):

fdns [OPTIONS]

Start the monitor (regular user):

fdns --monitor

DESCRIPTION

FDNS is an encrypted DNS proxy server for small networks and Linux desktops. To speed up the name resolution FDNS caches the responses, and uses a configurable adblocker and privacy filter to cut down the unnecessary traffic.

We preconfigure FDNS with a large list of DoH/DoT service providers. For privacy reasons we use only services from non-logging providers. We prefer servers run out-of-pocket by students, engineers, open-source enthusiasts, privacy-oriented non-profit organizations, etc. Currently there are more than 100 such servers on our list.

We also track a corporate category with several providers: Adguard, CleanBrowsing, Cloudflare, and Quad9. All have a non-logging privacy policy that will work in most parts of the world.

The servers are organized using a simple geographically-aware tagging system. This allows the user to request specialized services such as adblocking, security, family filters, etc.

Once started, FDNS chooses a server at random, as close geographically as possible. We derive the computer location from the timezone setting. There are no IP packets sent out to geolocation services. Three geographical zones are defined so far: Americas, AsiaPacific and Europe. Use --list=all option to print all the servers and the corresponding tags.

OPTIONS

--allow-all-queries

Allow all DNS query types; by default only A queries are allowed. In case --ipv6 is set, AAAA queries are also allowed.

--allow-expired-certs

Allow expired SSL certificates during SSL connection.

--allow-self-signed-certs

Allow self-signed SSL certificates during SSL connection. Use this option for bringing up new servers.

--blocklist=domain

Block domain and return NXDOMAIN.

Note: Blocking domains can also be requested in /etc/fdns/hosts file. This setting is global, and it will block the domains in all fdns instances running on your computer. Use --blocklist when you have multiple fdns proxies running, each instance with a different blocklist.

Example:
$ fdns --blocklist=fonts.googleaps.com

--blocklist-file=filename

Block all domains listed in the file.

--cache-ttl=seconds

Change DNS cache TTL, in seconds. By default we use a fixed cache TTL of 40 minutes.

--certfile=filename

Use an SSL certificate file in PEM format. By default we use the certificates installed by OpenSSL.

Example:
$ sudo fdns --certfile=/etc/ssl/certs/ca-certificates.crt

--daemonize

Detach from the controlling terminal and run as a Unix daemon. The typical way to start FDNS as network proxy is

$ sudo fdns --proxy-addr-any --daemonize

--debug

Print debug messages.

--debug-transport

Print HTTP2 debug messages.

--debug-ssl

Print SSL/TLS debug messages.

--details

SSL connection information, HTTP headers and network traces are printed on the screen during the testing phase of the connection.

Example:
$ fdns --test-server=cloudflare --details
Testing server cloudflare
Tags: anycast, Americas, AsiaPacific, Europe
URL: https://cloudflare-dns.com/dns-query
Bootstrap IP address: 1.1.1.1
Port: 443
TLSv1.3, ALPN h2, SNI no

Network Trace:
-----> rx 60 bytes: IP + TCP + TLS + H2-WINDOW-UPDATE
-----> rx 187 bytes: IP + TCP + TLS + H2-HEADERS + H2-DATA (end stream)

DoH query average: 64.38 ms
Header uncompressed | compressed | ratio: 185 | 28 | 6.61:1
DoH/Do53 bandwidth ratio: 2.50
Keepalive: 40 seconds

Testing completed

--disable-local-doh

Disable DoH services for applications running on the local network. NOTE: Applications can still use an external DoH server if they have a hardcoded IP-Address. If you realy want to block other DoH connection you must use your firewall.

--disable-syslog

Disable system logging.

--forwarder=domain@address

Conditional domain forwarding to a different DNS server.

Example:
$ sudo fdns --forwarder=libre@66.70.228.164

The proxy will forward all .libre domains to OpenNIC server at 66.70.228.164.

--help, -?, -h

Print command-line options and exit.

--ipv6

Allow AAAA requests. Use this option if you have Internet IPv6 connectivity. By default IPv6 queries are disabled.

--keepalive=value

Use this session keepalive value instead of the one in the server file. A query for example.com domain is initiated if there is no DNS query activity in order to keep the HTTP 2 connection open. For most servers we are using values between 25 and 40 seconds. In many cases you can bump the keepalive above 120 seconds.

Example:
$ sudo fdns --keepalive=120 --server=coudflare

--list

List the DoH service providers available in your current zone.

Example:
$ fdns --list
Current zone: Europe
42l - France, Europe
https://42l.fr
aaflalo - Netherlands, Europe, adblocker
https://www.aaflalo.me
appliedprivacy - Austria, Europe
https://appliedprivacy.net
bortzmeyer - France, Europe
https://www.bortzmeyer.org/doh-bortzmeyer-fr-policy.html
cznic - Czechia, Europe
https://www.nic.cz/odvr/
[...]

--list=server-name|tag|all

List the available DoH service providers based on a tag, server name, or all.

--log-timeout=minutes

Amount of time queries are kept in the log for monitoring purposes, default 10 minutes, maximum 1140 (one day). After the timeout expires, the queries are removed from the log.

Example:
$ sudo fdns --log-timeout=60

--monitor

Start the stats monitor. Without specifying an IP address (see below), the monitor is looking for a proxy at 127.1.1.1. If it fails, it looks for a proxy on the regular loopback address 127.0.0.1. If it fails again, it will display a proxy found on any other addresses.

Example:
$ fdns --monitor

--monitor=proxy-address

Start the stats monitor for a specific FDNS instance. Run this command as a regular user in a terminal.

Example:
$ fdns --monitor=127.2.2.2

--nofilter

No DNS request filtering. This disables all domain filters (adblocker, trackersetc.) and the user hosts file installed in /etc/fdns directory.

--proxies

List all running instances of FDNS.

Example:
$ fdns --proxies
pid 4900, address 127.3.3.3
pid 4893, address 127.2.2.2
pid 4883, address 127.1.1.1 (default)

--proxy-addr=address

Configure the IP address the proxy listens on for DNS queries coming from the local clients. The default is 127.1.1.1.

Example:
$ sudo fdns --proxy-addr=127.0.0.1

--proxy-addr-any

Listen on all available system interfaces and 127.0.0.1 for loopback interface.

--qps=number

Queries per second rate limit for resolver processes, default 5. When the limit is reached, incoming packets from the local network are dropped.

--resolvers=number

The number of resolver processes, between 1 and 10, default 3.

--server=server-name|tag|all|url

Connect to a specific server, or to a random one based on the tag and your geographical location. Using "all" will instruct FDNS to chose a server at random from the list, regardless where the server is located. You can also specify a DoH URL for servers not yet supported by FDNS.

Examples:
$ sudo fdns --server=cloudflare
$ sudo fdns --server=security
$ sudo fdns --server=family
$ sudo fdns --server=https://dns.google/dns-query
$ sudo fdns --server=dot://dot1.applied-privacy.net

--test-server

Test all the servers from your geographical zone.

Example:
$ fdns --test-server
Testing server aaflalo-adblocker
SSL connection opened in 309.55 ms
DoH response average 64.92 ms
Testing server adguard
SSL connection opened in 281.80 ms
DoH response average 55.44 ms
Testing server cleanbrowsing
SSL connection opened in 281.73 ms
DoH response average 57.90 ms
Testing server cloudflare
SSL connection opened in 251.37 ms
DoH response average 58.23 ms
Testing server dnscrypt-ca
SSL connection opened in 421.59 ms
DoH response average 83.51 ms

--test-server=server-name|tag|all

Test the servers based on a tag, server name, or all. Specifying a URL allows you to test servers not yet supported by FDNS.

Example:
$ fdns --test-server=digital-society
SSL connection opened in 640.53 ms
DoH response average 155.22 ms

$ fdns --test-server=https://dns.google/dns-query
SSL connection opened in 405.68 ms
DoH response average 78.86 ms

$ fdns --test-server=dot://dot1.applied-privacy.net
SSL/TLS connection: 770.46 ms
DoT query average: 137.26 ms

--test-url=URL

Check if URL is dropped by the adblock/tracker filters.

Example:
$ fdns --test-url=amazon-adsystem.com
URL amazon-adsystem.com dropped by "amazon-adsystem.com" rule

--test-url-list

Check URLs as they are introduced on STDIN.

Example:
$ cat biglist.txt | fdns --test-url-list

--unlist=server

Remove the server from the list for this FDNS instance.

Example:
$ fdns --unlist=quad9 --unlist=quad9-2

FDNS will not attempt to connect to quad9 and quad9-2 in the example above.

--version

Print program version and exit.

--whitelist=domain

Whitelist mode: resolve only the specified domains and drop everything else.

Example:
$ sudo fdns --whitelist=gentoo.org \
--whitelist=assets.gentoo.org \
--whitelist=security.gentoo.org \
--whitelist=wiki.gentoo.org

--whitelist-file=file-name

Similar to --whitelist above, it gets the domains from a file. If running under AppArmor, put the file under /etc/fdns directory. This is the only directory allowed by our AppArmor profile.

Example:
$ cat /etc/fdns/whitelist-gentoo
# whitelist file for gentoo.org
gentoo.org
assets.gentoo.org
security.gentoo.org
wiki.gentoo.org

$ sudo fdns --whitelist-file=/etc/fdns/whitelist-gentoo

Setup FDNS on a workstation

You would need to set FDNS as your DNS server in /etc/resolv.conf:

$ cat /etc/resolv.conf
nameserver 127.1.1.1

You can also use Firejail security sandbox to redirect all the DNS traffic to 127.1.1.1, where FDNS listens by default. Firejail decouples the DNS functionality, allowing each sandbox to have its own DNS setting. Your system DNS configuration is not touched. If things go wrong, you won't lose your Internet connectivity. Here are the steps:

Start FDNS:: $ sudo fdns
Start your applications in Firejail:: $ firejail --dns=127.1.1.1 firefox
$ firejail --dns=127.1.1.1 transmission-qt
Start the monitor:: $ fdns --monitor

Setup FDNS as a network server

Install FDNS and set "nameserver 127.0.0.1" in /etc/resolv.conf. Start FDNS using --proxy-addr-any. The proxy will listen on all system interfaces, and 127.0.0.1 for loopback interface. The default 127.1.1.1 is not used in this case.

$ sudo fdns --proxy-addr-any --daemonize

Or you can run it only on a specific interface. Example assuming 192.168.1.44 is the IP address of eth0:

$ sudo fdns --proxy-addr=192.168.1.44 --daemonize

When using --daemonize, errors and warnings are posted to syslog.

Running multiple FDNS proxies on the same computer

On your computer, start a proxy for the all the kids on your network, and make the proxy available on interface eth0 on your computer at address 192.168.1.44:

$ sudo fdns --proxy-addr=192.168.1.44 --server=family --daemonize

Start a regular proxy for yourself:

$ sudo fdns --server=security --daemonize

Check the proxies status:

$ fdns --proxies
pid 11890, address 192.168.1.44
pid 12062, address 127.1.1.1 (default)

Monitor kids proxy:

$ fdns --monitor=192.168.1.44

Monitor your proxy:

$ fdns --monitor

Use the PID number from "fdns --proxies" to shutdown one proxy or another:

$ sudo kill -9 11890

In about 30 seconds all processes associated with this specific proxy will exit.

FAQ

How do I start FDNS when I power-on the computer?

The command you need to run at startup is

# /usr/bin/fdns --daemonize

Include this command in your system startup scripts. If your system uses Systemd (Debian/.Ubuntu/Arch/RedHat etc.), enable the fdns.service unit provided in /etc/fdns/fdns.service.

$ sudo systemctl enable --now fdns.service

How do I configure Firejail to send all the DNS traffic to FDNS by default?

As root user, add the following two lines in /etc/firejail/globals.local. If the file doesn't exist, create it:

$ cat /etc/firejail/globals.local
dns 127.1.1.1
ignore dns

How do I save a list with all the DNS requests?

Start FDNS this way:

$ sudo fdns | tee dnslist.txt

How do I check FDNS is running in the background?

Use "--proxies" command to list all FDNS proxies running on your computer:

$ fdns --proxies
pid 12062, address 127.1.1.1 (default)

Or run ss and look for sockets open on port 53:

$ sudo ss -nulp
State Recv-Q Send-Q Local Address:Port Peer Address:Port
UNCONN 0 0 127.1.1.1:53 0.0.0.0:* users:(("fdns",pid=4227,fd=11))
UNCONN 0 0 127.1.1.1:53 0.0.0.0:* users:(("fdns",pid=4226,fd=9))
UNCONN 0 0 127.1.1.1:53 0.0.0.0:* users:(("fdns",pid=4225,fd=7))

How do I shut down FDNS?

$ sudo pkill fdns

FILES

/etc/fdns/adblocker - adblocker filter distributed with FDNS
/etc/fdns/coinblocker - cryptomining filter distributed with FDNS
/etc/fdns/fdns.service - systemd service file
/etc/fdns/fp-trackers - first-party tracker filter
/etc/fdns/hosts - user hosts file
/etc/fdns/phishing - phishing filter
/etc/fdns/resolver.seccomp - seccomp filter applied to resolver processes
/etc/fdns/servers - DoH/DoT servers FDNS knows about
/etc/fdns/trackers - tracker filter distributed with FDNS

LICENSE

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

Homepage: https://firejaildns.wordpress.com
Development: https://github.com/netblue30/fdns

fdns(1)