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ab2670b Jan 7, 2017
@jedisct1 @GaneJ
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Using the DNSCrypt client on Windows

dnscrypt-proxy is DNSCrypt client that works on many platforms, including Windows.

It doesn't provide any user interface, and has to be set up using the command-line.

Independent projects such as Simple DNSCrypt provide a user interface on top of dnscrypt-proxy, so that the core client code can always be up-to-date, and the same as other platforms.

However, using dnscrypt-proxy directly is fairly simple and opens a lot of options.

Quickstart

The following instructions are provided as offline documentation, but better/more up to date information is available online: dnscrypt-proxy guide.

1) Download and extract the latest Windows package for dnscrypt.

2) Extract the dnscrypt-proxy-win32 or dnscrypt-proxy-win64 folder anywhere, but this has to be a permanent location.

3) The dnscrypt-resolver.csv file includes a list of public DNS resolvers supporting the DNSCrypt protocol. The most recent version can be previewed online: public DNS resolvers supporting DNSCrypt and downloaded: dnscrypt-resolvers.csv.

Choose one that fits your needs. Its identifier ("resolver name") is in the first column (for example: dnscrypt.org-fr).

4) Edit the configuration file dnscrypt-proxy.conf.

5) Open an elevated command prompt (see below), enter the dnscrypt-proxy folder and type:

.\dnscrypt-proxy.exe dnscrypt-proxy.conf --test=0

This command just tests if everything is properly installed on your end, and if the resolver is properly working. If everything looks fine, the command should display the server key fingerprint and exit right away.

If an error is displayed, retry with a different server.

5) So far, so good? Now, enable the service for real:

.\dnscrypt-proxy.exe --install-with-config-file=dnscrypt-proxy.conf

6) Open the network preferences ("Network connections", then select your network adapter and hit "Properties"). Then in the "Internet Protocol Version 4 (TCP/IPv4)" settings use 127.0.0.1 instead of the default DNS resolver address.

Congratulations, you're now using DNSCrypt!

IPv6

Do you have IPv6 connectivity? No problem!

In the preferences pane for a given network connection, Windows has IPv6-specific settings under "Internet Protocol Version 6 (TCP/IPv6)".

The DNS server addresses have to be IPv6 addresses, so enter the IPv6 representation of 127.0.0.1:

::FFFF:127.0.0.1

Done. You can now enjoy the DNSCrypt proxy both for IPv4 and IPv6 connections.

How to open an elevated command prompt

On Windows 8.1 and Windows 10, press the Windows key + the X key and select "Windows Command Prompt (Admin)" or "Windows PowerShell (Admin)".

If you get the message:

[ERROR] Unable to bind (UDP) [Address already in use [WSAEADDRINUSE ]]

chances are that you tried to start the proxy from a limited (non-elevated) command prompt.

Temporarily disabling DNSCrypt

dnscrypt-proxy receives DNS queries from your applications on 127.0.0.1 (by default), wraps them into DNSCrypt queries, forwards them to the real DNS resolver, securely receives and verifies the responses, and forwards the legitimate ones to your client applications.

If you changed the DNS settings for a given network interface to 127.0.0.1, you can revert these settings to what they used to be (or to any non-DNSCrypt resolver) anytime in order to stop using DNSCrypt. Changing the address back to 127.0.0.1 makes the network interface use the DNSCrypt proxy again.

The Windows service

On Windows, dnscrypt-proxy can run as a Windows service, and this is how it was set up in the quickstart section above.

In addition to the command-line switches available on other platforms, the Windows builds of the proxy add the following switches:

  • --install: install the proxy as a service.
  • --install-with-config-file=<config file>: install the proxy as a service, using the provided configuration file (dnscrypt-proxy.conf). Double check that the configuration file is valid prior to installing the service.
  • --uninstall: uninstall the service (but not the software - the service can be restarted later)
  • --service-name=<name>: set the service name (by default: dnscrypt-proxy). Multiple services with a different configuration can run simultaneously if they use distinct service names. --service-name must be combined with --install, --install-with-config-file or --uninstall.

Example: how to try a different DNSCrypt resolver:

Step 1 - Uninstall the previous service:

.\dnscrypt-proxy --uninstall

Step 2 - Reinstall/restart the service, with the new settings:

.\dnscrypt-proxy -R <new name> --install

Sharing the proxy with the local network

By default, only the Windows machine running the proxy can use it.

However, it can be convenient to make it accessible from any device on the local network. For example, smartphones and tablets can use the Windows machine as a DNS resolver (which will actually be the DNSCrypt proxy) instead of running DNSCrypt themselves.

In order to do so, just add the following option to the command-line: --local-address=0.0.0.0.

That is:

.\dnscrypt-proxy -R <name> --install --local-address=0.0.0.0

And use the IP address of the Windows machine in the DNS settings of any devices of the local network.

Removing the software from the system

If this DNSCrypt client doesn't fit your needs, we are very sorry for this, and we'd love to hear about how we could make it better.

So, go to the "Support" section of the DNSCrypt site and tell us your story.

Removing dnscrypt-proxy from your system is straightforward.

Before doing so, make sure that the DNS settings of your network interfaces have been restored to what they were before (which, most of the time, is just "DHCP").

Then, uninstall the service:

.\dnscrypt-proxy --uninstall

And delete the directory.

Advanced configuration

Many additional features (logging, filtering...) can be enabled by loading a configuration file. This requires at least dnscrypt-proxy version 1.8.0.

1) Make sure that the service is not running:

.\dnscrypt-proxy --uninstall

2) Edit the dnscrypt-proxy.conf configuration file according to your needs.

3) Check that that configuration actually works as expected, by starting the proxy without installing the service:

.\dnscrypt-proxy dnscrypt-proxy.conf

Check that errors are not printed, and that DNS queries sent to the configured IP addresses receive responses. Hit Control+C in order to stop the server and get back to the interactive command prompt.

4) If that setup looks fine, install the Windows service so that it loads that configuration file automatically:

.\dnscrypt-proxy --install-with-config-file=dnscrypt-proxy.conf

Plugins

Plugins should be listed as paths to the .DLL files, optionally followed by a coma and plugin-specific arguments:

.\dnscrypt-proxy -R <name> --plugin=libdcplugin_example_ldns_aaaa_blocking.dll
.\dnscrypt-proxy -R <name> --plugin=libdcplugin_example_ldns_blocking.dll,--domains=C:\blacklisted-domains.txt

The service should be restarted after the registry has been updated.

Windows registry keys

Startup options can specified as subkeys from a registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\dnscrypt-proxy\Parameters

By default, the service is named dnscrypt-proxy, but this can be changed with the --service-name command-line switch when installing the service.

The following registry values are recognized:

Registry Value Type
ConfigFile REG_SZ
ResolversList REG_SZ
ResolverName REG_SZ
LocalAddress REG_SZ
ProviderKey REG_SZ
ProviderName REG_SZ
ResolverAddress REG_SZ
EDNSPayloadSize REG_DWORD
MaxActiveRequests REG_DWORD
TCPOnly REG_DWORD
EphemeralKeys REG_DWORD
IgnoreTimestamps REG_DWORD
ClientKeyFile REG_SZ
LogFile REG_SZ
LogLevel REG_DWORD
Plugins REG_MULTI_SZ

Detail of registry values:

ResolversList     : Full path to the `dnscrypt-resolvers.csv` file.
                    Equivalent to the `resolvers-list` parameter.
ResolverName      : Resolver name in the `dnscrypt-resolvers.csv` file.
                    This is the first column (`Name`) in that CSV file.
                    Equivalent to the `resolver-name` parameter.
LocalAddress      : IP address where `dnscrypt-proxy` listen for DNS request.
                    Equivalent to the `local-address` parameter.
ProviderKey       : DNS server key.
                    `Provider public key` column in the `dnscrypt-resolvers.csv` file.
                    Equivalent to the `provider-key` parameter.
ProviderName      : DNS server name.
                    `Provider name` column in the `dnscrypt-resolvers.csv` file.
                    Equivalent to the `provider-name` parameter.
ResolverAddress   : DNS server IP.
                    `Resolver address` column in the `dnscrypt-resolvers.csv` file.
                    Equivalent to the `resolver-address` parameter.
EDNSPayloadSize   : EDNS size.
                    Must be between `1` and `65507` (IPv4) or `65535` (IPv6-only).
                    Equivalent to the `edns-payload-size` parameter.
MaxActiveRequests : Maximum number of client DNS requests to process concurrently.
                    Must be equal or greater than `1`.
                    Equivalent to the `max-active-requests` parameter.
TCPOnly           : Send DNS queries to upstream servers using only TCP if set to `1`.
                    Must be `1` or `0`.
                    Equivalent to the `tcp-only` parameter.
EphemeralKeys     : Create a new key pair for every query.
                    Must be `1` or `0`.
                    Equivalent to the `ephemeral-keys` parameter.
IgnoreTimestamps  : Must be `1` or `0`.
                    Equivalent to the `ignore-timestamps` parameter. Do not enable blindly.
ClientKeyFile     : Use a static key pair. This is the path to a file storing the secret key.
                    Equivalent to the `client-key` parameter.
LogFile           : Log file for `dnscrypt-proxy`.
                    Equivalent to the `logfile` parameter.
LogLevel          : Maximum log level.
                    Equivalent to the `loglevel` parameter.
Plugins           : Set of plugins to be loaded by `dnscrypt-proxy`.
                    Equivalent to one or more `plugin` command-line arguments.

Plugins Example (INF):

HKLM,"SYSTEM\CurrentControlSet\services\dnscrypt-proxy\Parameters",0x10000,"C:\Program Files\DNSCrypt\libdcplugin_example_ldns_blocking.dll,--domains=C:\Program Files\DNSCrypt\Names.txt,--ips=C:\Program Files\DNSCrypt\IPs.txt,--logfile=C:\DNSCrypt-Block.log"

For example, in order to listen to a local address different from the default 127.0.0.1, the key to put the custom IP address in is HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\dnscrypt-proxy\Parameters\LocalAddress.

Unless ConfigFile is set, two entries are mandatory:

  • ResolversList: has to be set to the full path to the dnscrypt-resolvers.csv file.
  • ResolverName: has to be set to the resolver name to be used. See the dnscrypt-resolvers.csv file for a list of compatible public resolvers.

These entries are automatically created/updated when installing the service.