<chapter xmlns="http://docbook.org/ns/docbook"
         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="sec-dnscrypt-proxy">

  <title>DNSCrypt client proxy</title>

  <para>
    The DNSCrypt client proxy relays DNS queries to a DNSCrypt enabled
    upstream resolver. The traffic between the client and the upstream
    resolver is encrypted and authenticated, mitigating the risk of MITM
    attacks, DNS poisoning attacks, and third-party snooping (assuming the
    upstream is trustworthy).
  </para>

  <sect1><title>Basic configuration</title>

  <para>
    To enable the client proxy, set
    <programlisting>
      services.dnscrypt-proxy.enable = true;
    </programlisting>
  </para>

  <para>
    Enabling the client proxy does not alter the system nameserver; to
    relay local queries, prepend <literal>127.0.0.1</literal> to
    <option>networking.nameservers</option>.
  </para>

  </sect1>

  <sect1><title>As a forwarder for a caching DNS client</title>

  <para>
    By default, DNSCrypt proxy acts as a transparent proxy for the
    system stub resolver. Because the client does not cache lookups, this
    setup can significantly slow down e.g., web browsing. The recommended
    configuration is to run DNSCrypt proxy as a forwarder for a caching DNS
    client. To achieve this, change the default proxy listening port to
    a non-standard value and point the caching client to it:
    <programlisting>
      services.dnscrypt-proxy.localPort = 43;
    </programlisting>
  </para>

  <sect2><title>dnsmasq</title>
  <para>
    <programlisting>
      {
      services.dnsmasq.enable = true;
      services.dnsmasq.servers = [ "127.0.0.1#43" ];
      }
    </programlisting>
  </para>
  </sect2>

  <sect2><title>unbound</title>
  <para>
    <programlisting>
      {
      networking.nameservers = [ "127.0.0.1" ];
      services.unbound.enable = true;
      services.unbound.forwardAddresses = [ "127.0.0.1@43" ];
      services.unbound.extraConfig = ''
        do-not-query-localhost: no
      '';
      }
    </programlisting>
  </para>
  </sect2>

  </sect1>

</chapter>
