更新的时候发现没有网
root@ubuntu22:~# sudo apt update
Ign:1 http://archive.ubuntu.com/ubuntu jammy InRelease
Ign:2 http://archive.ubuntu.com/ubuntu jammy-updates InRelease
Ign:3 http://archive.ubuntu.com/ubuntu jammy-backports InRelease
Ign:4 http://archive.ubuntu.com/ubuntu jammy-security InRelease
Ign:1 http://archive.ubuntu.com/ubuntu jammy InRelease
Ign:2 http://archive.ubuntu.com/ubuntu jammy-updates InRelease
Ign:3 http://archive.ubuntu.com/ubuntu jammy-backports InRelease
Ign:4 http://archive.ubuntu.com/ubuntu jammy-security InRelease
Ign:1 http://archive.ubuntu.com/ubuntu jammy InRelease
Ign:2 http://archive.ubuntu.com/ubuntu jammy-updates InRelease
Ign:3 http://archive.ubuntu.com/ubuntu jammy-backports InRelease
Ign:4 http://archive.ubuntu.com/ubuntu jammy-security InRelease
Err:1 http://archive.ubuntu.com/ubuntu jammy InRelease
Temporary failure resolving 'archive.ubuntu.com'
Err:2 http://archive.ubuntu.com/ubuntu jammy-updates InRelease
Temporary failure resolving 'archive.ubuntu.com'
Err:3 http://archive.ubuntu.com/ubuntu jammy-backports InRelease
Temporary failure resolving 'archive.ubuntu.com'
Err:4 http://archive.ubuntu.com/ubuntu jammy-security InRelease
Temporary failure resolving 'archive.ubuntu.com'
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/jammy/InRelease Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/jammy-updates/InRelease Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/jammy-backports/InRelease Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/jammy-security/InRelease Temporary failure resolving 'archive.ubuntu.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.只能先临时改下DNS
cat /etc/resolv.confroot@ubuntu22:~# cat /etc/resolv.conf
# This is /run/systemd/resolve/stub-resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# 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 "resolvectl status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs should typically 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 trust-ad
search localdomain备份一下
cp /etc/resolv.conf /etc/resolv.conf"$(date +'%Y-%m-%d_%H-%M-%S')"编辑DNS
vim /etc/resolv.conf加入如下两行
nameserver 8.8.4.4
nameserver 8.8.8.8完整示例
# This is /run/systemd/resolve/stub-resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# 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 "resolvectl status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs should typically 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 trust-ad
search localdomain
nameserver 8.8.4.4
nameserver 8.8.8.8此时再更新就正常了
root@ubuntu22:~# sudo apt update
Hit:1 http://archive.ubuntu.com/ubuntu jammy InRelease
Get:2 http://archive.ubuntu.com/ubuntu jammy-updates InRelease [114 kB]
Get:3 http://archive.ubuntu.com/ubuntu jammy-backports InRelease [99.8 kB]
Get:4 http://archive.ubuntu.com/ubuntu jammy-security InRelease [110 kB]
Get:5 http://archive.ubuntu.com/ubuntu jammy/main amd64 c-n-f Metadata [30.3 kB]
Get:6 http://archive.ubuntu.com/ubuntu jammy/restricted amd64 c-n-f Metadata [488 B]
Get:7 http://archive.ubuntu.com/ubuntu jammy/universe amd64 c-n-f Metadata [286 kB]
Get:8 http://archive.ubuntu.com/ubuntu jammy/multiverse amd64 c-n-f Metadata [8,372 B]
Get:9 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages [698 kB]
Get:10 http://archive.ubuntu.com/ubuntu jammy-updates/main Translation-en [159 kB]
Get:11 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 c-n-f Metadata [10.8 kB]
Get:12 http://archive.ubuntu.com/ubuntu jammy-updates/restricted amd64 Packages [417 kB]
Get:13 http://archive.ubuntu.com/ubuntu jammy-updates/restricted Translation-en [63.9 kB]
Get:14 http://archive.ubuntu.com/ubuntu jammy-updates/restricted amd64 c-n-f Metadata [580 B]
Get:15 http://archive.ubuntu.com/ubuntu jammy-updates/universe amd64 Packages [747 kB]
Get:16 http://archive.ubuntu.com/ubuntu jammy-updates/universe Translation-en [123 kB]
Get:17 http://archive.ubuntu.com/ubuntu jammy-updates/universe amd64 c-n-f Metadata [4,404 B]
Get:18 http://archive.ubuntu.com/ubuntu jammy-updates/multiverse amd64 Packages [7,220 B]
Get:19 http://archive.ubuntu.com/ubuntu jammy-updates/multiverse Translation-en [2,360 B]
Get:20 http://archive.ubuntu.com/ubuntu jammy-updates/multiverse amd64 c-n-f Metadata [420 B]
Get:21 http://archive.ubuntu.com/ubuntu jammy-backports/main amd64 Packages [3,008 B]
Get:22 http://archive.ubuntu.com/ubuntu jammy-backports/main Translation-en [1,432 B]
Get:23 http://archive.ubuntu.com/ubuntu jammy-backports/main amd64 c-n-f Metadata [272 B]
Get:24 http://archive.ubuntu.com/ubuntu jammy-backports/restricted amd64 c-n-f Metadata [116 B]
Get:25 http://archive.ubuntu.com/ubuntu jammy-backports/universe amd64 Packages [6,744 B]
Get:26 http://archive.ubuntu.com/ubuntu jammy-backports/universe Translation-en [9,360 B]
Get:27 http://archive.ubuntu.com/ubuntu jammy-backports/universe amd64 c-n-f Metadata [352 B]
Get:28 http://archive.ubuntu.com/ubuntu jammy-backports/multiverse amd64 c-n-f Metadata [116 B]
Get:29 http://archive.ubuntu.com/ubuntu jammy-security/main amd64 Packages [462 kB]
Get:30 http://archive.ubuntu.com/ubuntu jammy-security/main Translation-en [102 kB]
Get:31 http://archive.ubuntu.com/ubuntu jammy-security/main amd64 c-n-f Metadata [3,924 B]
Get:32 http://archive.ubuntu.com/ubuntu jammy-security/restricted amd64 Packages [376 kB]
Get:33 http://archive.ubuntu.com/ubuntu jammy-security/restricted Translation-en [57.6 kB]
Get:34 http://archive.ubuntu.com/ubuntu jammy-security/restricted amd64 c-n-f Metadata [524 B]
Get:35 http://archive.ubuntu.com/ubuntu jammy-security/universe amd64 Packages [606 kB]
Get:36 http://archive.ubuntu.com/ubuntu jammy-security/universe Translation-en [77.1 kB]
Get:37 http://archive.ubuntu.com/ubuntu jammy-security/universe amd64 c-n-f Metadata [2,408 B]
Get:38 http://archive.ubuntu.com/ubuntu jammy-security/multiverse amd64 c-n-f Metadata [228 B]
Fetched 4,594 kB in 7s (633 kB/s)
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
96 packages can be upgraded. Run 'apt list --upgradable' to see them.
root@ubuntu22:~# 但是这样配置DNS在重启了服务器之后DNS还会被还原，因此需要更改DNS使其永久生效
因为我是国内机子，因此需要先更换成国内的源，这里以清华源为例：
https://mirrors.tuna.tsinghua.edu.cn/help/ubuntu/
备份一下
cp /etc/apt/sources.list /etc/apt/sources.list"$(date +'%Y-%m-%d_%H-%M-%S')"删除旧的“源”文件并重新创建
rm -rf /etc/apt/sources.list
vim /etc/apt/sources.list将下面的“源”配置粘贴到/etc/apt/sources.list
# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-updates main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-backports main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-security main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-security main restricted universe multiverse
# 预发布软件源，不建议启用
# deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-proposed main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-proposed main restricted universe multiverse安装resolvconf并允许resolvconf开机自启
sudo apt update
sudo apt install resolvconf
sudo systemctl status resolvconf.service
sudo systemctl start resolvconf.service
sudo systemctl enable resolvconf.service
sudo systemctl status resolvconf.service
接下来设定永久生效的DNS
vim /etc/resolvconf/resolv.conf.d/head加入如下两行
nameserver 8.8.4.4
nameserver 8.8.8.8
重启resolvconf
sudo systemctl restart resolvconf.service
sudo systemctl restart systemd-resolved.service重启之后可以看到resolv.conf已经被自动更新了，之后重启服务器之后该DNS也会自动生效
root@ubuntu22:/etc/ssh# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.
nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 127.0.0.53
search localdomain
options edns0 trust-ad
ubuntu-22.04-live-server-amd64.iso