DNSCrypt (简体中文) - ArchWiki

# DNSCrypt (简体中文)

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翻译状态： 本文是英文页面 DNSCrypt 的翻译，最后翻译时间：2018-06-30，点击这里可以查看翻译后英文页面的改动。

DNSCrypt 可以加密和认证用户和 DNS 解析服务器之间的数据传输。IP 数据本身没有任何变化，DNScrypt 可以避免 DNS 查询欺骗，确保 DNS 相应来自选择的 DNS 服务器。[1]

## 安装

安装 软件包 dnscrypt-proxy。

## Configuration

### Startup

The service can be started in two mutually exclusive ways (i.e. only one of the two may be enabled):

- With the `.service` file.

Note: The `listen_addresses` option must configured (e.g. `listen_addresses = ['127.0.0.1:53', '[::1]:53']`) in the configuration file when using the `.service` file.

- Through the `.socket` activation.

Note: When using socket activation the `listen_addresses` option must be set to empty (i.e. `listen_addresses = [ ]`) in the configuration file, since systemd is taking care of the socket configuration.

### Select resolver

By leaving `server_names` commented out in the configuration file `/etc/dnscrypt-proxy/dnscrypt-proxy.toml`, dnscrypt-proxy will choose the fastest server from the sources already configured under `[sources]` [2]. The lists will be downloaded, verified, and automatically updated. [3]. Thus, configuring a specific set of servers is optional.

To manually set which server is used, edit `/etc/dnscrypt-proxy/dnscrypt-proxy.toml` and uncomment the `server_names` variable, selecting one or more of the servers. For example, to use Cloudflare's servers:

    server_names = ['cloudflare', 'cloudflare-ipv6']

A full list of resolvers is located at the upstream page or Github. If dnscrypt-proxy has run successfully on the system before, `/var/cache/dnscrypt-proxy/public-resolvers.md` will also contain a list. Look at the description for servers note which validate DNSSEC, do not log, and are uncensored. These requirements can be configured globally with the `require_dnssec`, `require_nolog`, `require_nofilter` options.

### Disable any services bound to port 53

Tip: If using #Unbound as your local DNS cache this section can be ignored, as unbound runs on port 53 by default.

To see if any programs are using port 53, run

     $ ss -lp 'sport = :domain'

If the output contains more than the first line of column names, you need to disable whatever service is using port 53. One common culprit is `systemd-resolved.service`, but other network managers may have analogous components. You are ready to proceed once the above command outputs nothing more than the following line:

     Netid               State                 Recv-Q                Send-Q                                 Local Address:Port                                   Peer Address:Port

### Modify resolv.conf

This article or section needs expansion.

Reason: Explain what the options mean. (Discuss in Talk:DNSCrypt (简体中文)#)

Modify the resolv.conf file and replace the current set of resolver addresses with the address for localhost and options [4]:

    nameserver 127.0.0.1
    options edns0 single-request-reopen

Other programs may overwrite this setting; see resolv.conf#Preserve DNS settings[broken link: invalid section] for details.

### Start systemd service

Finally, start/enable the `dnscrypt-proxy.service` unit or `dnscrypt-proxy.socket`, depending on which method you chose above.

## Tips and tricks

### Local DNS cache configuration

Tip: dnscrypt can cache entries without relying on another program. This feature is enabled by default with the line `cache = true` in your dnscrypt configuration file

It is recommended to run DNSCrypt as a forwarder for a local DNS cache if not using dnscrypt's cache feature; otherwise, every single query will make a round-trip to the upstream resolver. Any local DNS caching program should work. In addition to setting up dnscrypt-proxy, you must setup your local DNS cache program.

#### Change port

In order to forward queries from a local DNS cache, dnscrypt-proxy should listen on a port different from the default `53`, since the DNS cache itself needs to listen on `53` and query dnscrypt-proxy on a different port. Port number `53000` is used as an example in this section. In this example, the port number is larger than 1024 so dnscrypt-proxy is not required to be run by root.

There are two methods for changing the default port:

Socket method

Edit `dnscrypt-proxy.socket` with the following contents:

    [Socket]
    ListenStream=
    ListenDatagram=
    ListenStream=127.0.0.1:53000
    ListenDatagram=127.0.0.1:53000

When queries are forwarded from the local DNS cache to `53000`, `dnscrypt-proxy.socket` will start `dnscrypt-proxy.service`.

Service method

Edit the `listen_addresses` option in `/etc/dnscrypt-proxy/dnscrypt-proxy.toml` with the following:

    listen_addresses = ['127.0.0.1:53000', '[::1]:53000']

#### Example local DNS cache configurations

The following configurations should work with dnscrypt-proxy and assume that it is listening on port `53000`.

##### Unbound

Configure Unbound to your liking (in particular, see Unbound#Local DNS server) and add the following lines to the end of the `server` section in `/etc/unbound/unbound.conf`:

      do-not-query-localhost: no
    forward-zone:
      name: "."
      forward-addr: 127.0.0.1@53000

Tip: If you are setting up a server, add `interface: 0.0.0.0@53` and `access-control: your-network/subnet-mask allow` inside the `server:` section so that the other computers can connect to the server. A client must be configured with `nameserver address-of-your-server` in `/etc/resolv.conf`.

Restart `unbound.service` to apply the changes.

##### dnsmasq

Configure dnsmasq as a local DNS cache[broken link: invalid section]. The basic configuration to work with DNSCrypt:

    /etc/dnsmasq.conf

    no-resolv
    server=127.0.0.1#53000
    listen-address=127.0.0.1

If you configured DNSCrypt to use a resolver with enabled DNSSEC validation, make sure to enable it also in dnsmasq:

    /etc/dnsmasq.conf

    proxy-dnssec

Restart `dnsmasq.service` to apply the changes.

##### pdnsd

Install pdnsd. A basic configuration to work with DNSCrypt is:

    /etc/pdnsd.conf

    global {
        perm_cache = 1024;
        cache_dir = "/var/cache/pdnsd";
        run_as = "pdnsd";
        server_ip = 127.0.0.1;
        status_ctl = on;
        query_method = udp_tcp;
        min_ttl = 15m;       # Retain cached entries at least 15 minutes.
        max_ttl = 1w;        # One week.
        timeout = 10;        # Global timeout option (10 seconds).
        neg_domain_pol = on;
        udpbufsize = 1024;   # Upper limit on the size of UDP messages.
    }

    server {
        label = "dnscrypt-proxy";
        ip = 127.0.0.1;
        port = 53000;
        timeout = 4;
        proxy_only = on;
    }

    source {
        owner = localhost;
        file = "/etc/hosts";
    }

Restart `pdnsd.service` to apply the changes.

### Sandboxing

Edit `dnscrypt-proxy.service` to include the following lines:

    [Service]
    CapabilityBoundingSet=CAP_IPC_LOCK CAP_SETGID CAP_SETUID CAP_NET_BIND_SERVICE
    ProtectSystem=strict
    ProtectHome=true
    ProtectKernelTunables=true
    ProtectKernelModules=true
    ProtectControlGroups=true
    PrivateTmp=true
    PrivateDevices=true
    MemoryDenyWriteExecute=true
    NoNewPrivileges=true
    RestrictRealtime=true
    RestrictAddressFamilies=AF_INET AF_INET6
    SystemCallArchitectures=native
    SystemCallFilter=~@clock @cpu-emulation @debug @keyring @ipc @module @mount @obsolete @raw-io

See systemd.exec(5) and Systemd#Sandboxing application environments for more information. Additionally see upstream comments[dead link 2018-01-08].

### Enable EDNS0

This article or section needs expansion.

Reason: Name the advantages/motivation for enabling this. (Discuss in Talk:DNSCrypt (简体中文)#)

Extension Mechanisms for DNS that, among other things, allows a client to specify how large a reply over UDP can be.

Add the following line to your `/etc/resolv.conf`:

    options edns0

This article or section is out of date.

Reason: dnscrypt-proxy2 uses different config file. (Discuss in Talk:DNSCrypt (简体中文)#)

You may also wish to append the following to `/etc/dnscrypt-proxy.conf`:

    EDNSPayloadSize <bytes>

Where <bytes> is a number, the default size being 1252, with values up to 4096 bytes being purportedly safe. A value below or equal to 512 bytes will disable this mechanism, unless a client sends a packet with an OPT section providing a payload size.

#### Test EDNS0

Make use of the DNS Reply Size Test Server, use the drill command line tool to issue a TXT query for the name rs.dns-oarc.net:

    $ drill rs.dns-oarc.net TXT

With EDNS0 supported, the "answer section" of the output should look similar to this:

    rst.x3827.rs.dns-oarc.net.
    rst.x4049.x3827.rs.dns-oarc.net.
    rst.x4055.x4049.x3827.rs.dns-oarc.net.
    "2a00:d880:3:1::a6c1:2e89 DNS reply size limit is at least 4055 bytes"
    "2a00:d880:3:1::a6c1:2e89 sent EDNS buffer size 4096"

### Redundant DNSCrypt providers

This section is being considered for removal.

Reason: Out of date and irrelevant since dnscrypt-proxy2 handles the configuration of multiple sources. (Discuss in Talk:DNSCrypt (简体中文)#)

To use several different dnscrypt providers, you may simply copy the original `dnscrypt-proxy.service` and `dnscrypt-proxy.socket`. Then in your new copy of the service change the command line parameters, either pointing to a new configuration file or naming a different resolver directly. From there change the port in the new copy of the socket. Lastly, update your local DNS cache program to point to new service's port. For example, with unbound the configuration file would look like if using ports `53000` for the original socket and `53001` for the new socket.

    /etc/unbound/unbound.conf

     do-not-query-localhost: no
     forward-zone:
       name: "."
       forward-addr: 127.0.0.1@53000
       forward-addr: 127.0.0.1@53001

#### Create instanced systemd service

An alternative option to copying the systemd service is to used an instanced service.

##### Create systemd file

First, create `/etc/systemd/system/dnscrypt-proxy@.service` containing:

    [Unit]
    Description=DNSCrypt client proxy
    Documentation=man:dnscrypt-proxy(8)
    Requires=dnscrypt-proxy@%i.socket

    [Service]
    Type=notify
    NonBlocking=true
    ExecStart=/usr/bin/dnscrypt-proxy \
        --resolver-name=%i
    Restart=always

This specifies an instanced systemd service that starts a dnscrypt-proxy using the service name specified after the @ symbol of a corresponding .socket file.

##### Add dnscrypt-sockets

To create multiple dnscrypt-proxy sockets, copy `/usr/lib/systemd/system/dnscrypt-proxy.socket` to a new file, `/etc/systemd/system/dnscrypt-proxy@short-name.here.socket`, replacing the socket instance name with one of the short names listed in `dnscrypt-resolvers.csv` and change the port. Use a different port for each instance (53000, 53001, and so forth).

##### Apply new systemd configuration

Now we need to reload the systemd configuration.

    # systemctl daemon-reload

Since we are replacing the default service with a different name, we need to explicitly stop and disable `dnscrypt-proxy.service` and `dnscrypt-proxy.socket`.

Now start/enable the new service(s), e.g., `dnscrypt-proxy@dnscrypt.eu-nl`, etc.

Finally restart `unbound.service`.

## See also

- Wikipedia:DNS over HTTPS

Categories:

- Domain Name System (简体中文)
- Encryption (简体中文)

Hidden categories:

- Pages or sections flagged with Template:Expansion
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