Dnscrypt-proxy (简体中文)
dnscrypt-proxy 可以加密和认证用户和 DNS 解析服务器之间的数据传输，支持 DNS over HTTPS 和 DNSCrypt，可以避免中间人攻击和窃听。dnscrypt-proxy 兼容 DNSSEC。
安装
安装 软件包 dnscrypt-proxy。
配置
启动
服务有两种启动方式，但是只能二选一：
- 启用
.service
listen_addresses (即在配置文件中写好 listen_addresses = ['127.0.0.1:53', '[::1]:53'])- 启用
.socket
listen_addresses (即 listen_addresses = [ ])，systemd 会自己配置好 socket选择解析服务器
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] [1]. The lists will be downloaded, verified, and automatically updated. [2]. 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.
禁用其他占用53端口的服务
查看占用 53 端口的服务：
$ ss -lp 'sport = :domain'
如果输出除了表头还有其他内容，你就需要禁用占用53端口的那些服务，比如 systemd-resolved.service 和其他网络管理器包含的类似服务。把它们全部干掉，直到上面的命令的输出只剩这个样子：
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
修改 resolv.conf
修改 resolv.conf，把现有的nameserver全部清掉，添一行指向 localhost 的地址（一般是 127.0.0.1）的nameserver；并增添一行 options [3]。示例如下：
nameserver ::1 nameserver 127.0.0.1 options edns0 single-request-reopen
其他程序可能会修改 resolv.conf，详见：resolv.conf#Overwriting of /etc/resolv.conf。
启动 systemd 服务
根据上面你选择的配置来 start/enable dnscrypt-proxy.service 或者 dnscrypt-proxy.socket
技巧
本地 DNS 缓存配置
cache = true in your dnscrypt configuration fileIt 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.
修改端口
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']
本地 DNS 缓存配置举例
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
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. 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.
沙盒隔离
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.
启用 EDNS0
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
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.
测试 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"