Ubuntu 18.04 永久修改DNS

每次在/etc/resolv.conf 修改DNS之后，重启服务器DNS就会重置为127.0.0.53

解决过程

1. 查看/etc/resolv.conf文件

➜  ~ cat  /etc/resolv.conf    
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "systemd-resolve --status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 127.0.0.53
options edns0

2. 发现问题

从/etc/resolv.conf的注释中发现systemd-resolved为本地应用程序提供了DNS解析服务。通过 systemd-resolved 在本地回环网口 127.0.0.53 上提供的本地DNS服务器。 应用程序可以直接向 127.0.0.53 发送DNS请求，从而直接使用 systemd-resolved 提供的解析服务。

解决方法

修改/etc/systemd/resolved.conf

1. 打开/etc/systemd/resolved.conf

vim /etc/systemd/resolved.conf

2. 修改DNS

[Resolve]
DNS=8.8.8.8
DNS=8.8.4.4
#FallbackDNS=
#Domains=
#LLMNR=no
#MulticastDNS=no
#DNSSEC=no
#Cache=yes
#DNSStubListener=yes

3. 重启服务

systemctl restart systemd-resolved.service

4. 查看结果

➜  ~ systemd-resolve --status
Global
         DNS Servers: 8.8.8.8
                      114.114.114.114
          DNSSEC NTA: 10.in-addr.arpa
                      16.172.in-addr.arpa
                      168.192.in-addr.arpa
                      17.172.in-addr.arpa
                      18.172.in-addr.arpa
                      19.172.in-addr.arpa
                      20.172.in-addr.arpa
                      21.172.in-addr.arpa
                      22.172.in-addr.arpa
                      23.172.in-addr.arpa
                      24.172.in-addr.arpa
                      25.172.in-addr.arpa
                      26.172.in-addr.arpa
                      27.172.in-addr.arpa
                      28.172.in-addr.arpa
                      29.172.in-addr.arpa
                      30.172.in-addr.arpa
                      31.172.in-addr.arpa
                      corp
                      d.f.ip6.arpa
                      home
                      internal