ubuntu修改dns

[TOC]

一、查看当前DNS

resolvectl status

在ubuntu22.04以下的系统中，应该使用systemd-resolve --status

root@111:~# resolvectl
Global
         Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
  resolv.conf mode: stub
Current DNS Server: 192.168.2.1
        DNS Servers 192.168.2.1 fe80::5

Link 2 (enp6s0)
    Current Scopes: DNS
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 192.168.2.1
       DNS Servers: 192.168.2.1 fe80::5

注意到需要修改两个地方的DNS，一个是Global，一个是Link 2 (enp6s0)

二、修改Global DNS

1.打开配置文件

vim /etc/systemd/resolved.conf

2.在 `[Resolve]` 部分添加或修改以下行：

DNS=223.6.6.6 1.1.1.1 119.29.29.29 2400:3200:baba::1 2606:4700:4700::1111 2402:4e00::

3.重启服务

sudo systemctl restart systemd-resolved

4.再次查看当前DNS

resolvectl status

root@111:~# resolvectl
Global
         Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
  resolv.conf mode: stub
Current DNS Server: 223.6.6.6
        DNS Servers 223.6.6.6 1.1.1.1 119.29.29.29 2400:3200:baba::1 2606:4700:4700::1111 2402:4e00::

Link 2 (enp6s0)
    Current Scopes: DNS
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 192.168.2.1
       DNS Servers: 192.168.2.1 fe80::5
root@111:~#

三、修改特定网卡的的DNS(这里以enp6s0为例)

1.进入netplan目录并查看文件

cd /etc/netplan
ls -lah

# root @ ubuntu in /etc/netplan [11:41:20]
$ cd /etc/netplan
ls -lah
总计 32K
drwxr-xr-x   2 root root 4.0K  2月 14 01:59 .
drwxr-xr-x 154 root root  12K  2月 14 02:29 ..
-rw-------   1 root root   49  7月 10  2024 01-network-manager-all.yaml.dpkg-backup
-rw-------   1 root root  287  2月 14 01:59 50-cloud-init.yaml
-rw-------   1 root root  771  2月 14 02:01 90-NM-065414f7-ecf2-42cc-be4e-a2a963949b3a.yaml
-rw-------   1 root root  540  2月 14 01:59 90-NM-6eb17bc8-a642-3fb0-8edf-601ed5a4c021.yaml

# root @ ubuntu in /etc/netplan [11:41:47]

2.根据网卡名找到对应的文件(比如enp6s0)

# root @ ubuntu in /etc/netplan [11:45:38] C:130
$ grep -rn 'enp6s0'
90-NM-6eb17bc8-a642-3fb0-8edf-601ed5a4c021.yaml:7:        name: "enp6s0"

3.vim编辑找到的文件

vim 90-NM-6eb17bc8-a642-3fb0-8edf-601ed5a4c021.yaml

可以看到文件内容

network:
  version: 2
  ethernets:
    NM-6eb17bc8-a642-3fb0-8edf-601ed5a4c021:
      renderer: NetworkManager
      match:
        name: "enp6s0"
      dhcp4: true
      dhcp6: true
      macaddress: "preserve"
      wakeonlan: true
      networkmanager:
        uuid: "6eb17bc8-a642-3fb0-8edf-601ed5a4c021"
        name: "ubu"
        passthrough:
          connection.autoconnect-priority: "-999"
          connection.timestamp: "1720592091"
          ipv6.addr-gen-mode: "default"
          ipv6.ip6-privacy: "-1"
          proxy._: ""

缺少nameservers需要手动添加,nameservers和networkmanager同级

network:
  version: 2
  ethernets:
    NM-6eb17bc8-a642-3fb0-8edf-601ed5a4c021:
      renderer: NetworkManager
      match:
        name: "enp6s0"
      dhcp4: true
      dhcp6: true
      macaddress: "preserve"
      wakeonlan: true
      networkmanager:
        uuid: "6eb17bc8-a642-3fb0-8edf-601ed5a4c021"
        name: "ubu"
        passthrough:
          connection.autoconnect-priority: "-999"
          connection.timestamp: "1720592091"
          ipv6.addr-gen-mode: "default"
          ipv6.ip6-privacy: "-1"
          proxy._: ""
      nameservers:
        addresses:
          - 223.6.6.6
          - 1.1.1.1
          - 119.29.29.29
          - 2400:3200:baba:0:0:0:0:1
          - 2606:4700:4700:0:0:0:0:1111
          - 2402:4e00:0:0:0:0:0:0

4.应用配置

netplan apply

此时ssh连接会断开，等30秒后重新连接ssh查看dns

5.查看修改后的dns

root@111:~# resolvectl
Global
         Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
  resolv.conf mode: stub
Current DNS Server: 223.6.6.6
        DNS Servers 223.6.6.6 1.1.1.1 119.29.29.29 2400:3200:baba::1 2606:4700:4700::1111 2402:4e00::
Link 2 (enp6s0)
    Current Scopes: DNS
         Protocols: +DefaultRoute -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 223.6.6.6
       DNS Servers: 223.6.6.6 1.1.1.1 119.29.29.29 192.168.2.1 2400:3200:baba::1 2606:4700:4700::1111 2402:4e00::
                    fe80::5
root@111:~#

此时系统优先使用的DNS已经是手动设置的了，但有时候还可以看到后面还是有几个DNS(有可能是路由器ip或者光猫ip或者运营商默认dns ip)，这是DHCP自动配置的DNS，完全禁用需要修改其他配置

ubuntu修改dns