Ubuntu 18.04.4的安装步骤

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这几天折腾NUC主机，在安装Ubuntu 18.04.4 LTS（长期支持的稳定版本）的过程中遇到不少坑，立此存照吧。

Step 0：安装前的准备工作

已安装内存和硬盘的NUC主机之外，还需要：

  • 独立显示器：感谢LP赞助的DELL S2319SP

  • USB键盘 + USB鼠标：开机BIOS设置硬件启动顺序时键盘操作不方便

  • 有线网络接口：备用先不接

  • Ubuntu启动U盘：制作方法参见如何制作Ubuntu的USB启动盘，Server版本912M，Desktop版本2.13G

Step 1: 安装Ubuntu Server

  1. 插入Ubuntu安装U盘，开机启动后进入安装界面，各种参数选默认

  2. 完成安装后拔出U盘，重新启动并登录进入新安装的Ubuntu Server
    开机启动过程中，可能需要在BIOS设置启动顺序（USB—STAT—LAN），进入方法是加电过程中持续按F2
    强烈建议安装Openssh Server，以后可以拔掉键盘和鼠标，直接远程登录管理主机
    安装过程中需要设置一个默认用户，root尚未激活
    由于安装过程中未接网线，完成后所有网络接口都不可用

step 2: 激活root用户

  1. 以默认用户身份设置root口令，并切换到root

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    sj@nuc5i3:~$ sudo passwd root
    [sudo] password for sj:
    Enter new UNIX password:
    Retype new UNIX password:
    passwd: password updated successfully

    sj@nuc5i3:~$ su -
    Password:

    root@nuc5i3:~#

  2. 如果需要允许root用户远程登录，修改配置文件/etc/ssh/sshd_config，将PermitRootLogin改为yes

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    #PermitRootLogin prohibit-password

Step 3: 设置有线网络接入

  1. 插入有线网络，没啥动静？ 别着急，还没配置网络参数呢！

  2. 编辑网卡配置文件/etc/netplan/50-cloud-init.yaml，至少需要设置IP地址和默认网关

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    # This file is generated from information provided by the datasource.  Changes
    # to it will not persist across an instance reboot.  To disable cloud-init's
    # network configuration capabilities, write a file
    # /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
    # network: {config: disabled}
    network:
        version: 2

        ethernets:
            enp0s25:
                dhcp4: no
                addresses: [192.168.0.130/24]
                gateway4: 192.168.0.1

  3. 使用netpaln generate刷新网络配置，netplan apply启动有线网卡
    最后用ifconfig检查网络状态，确认有线网卡enp0s25启动成功

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    root@nuc5i3:/etc/netplan# netplan generate
    root@nuc5i3:/etc/netplan# netplan apply

    root@nuc5i3:/etc/netplan# ifconfig
    enp0s25: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.0.130  netmask 255.255.255.0  broadcast 192.168.0.255
            inet6 fe80::baae:edff:fe73:87fb  prefixlen 64  scopeid 0x20<link>
            ether b8:ae:ed:73:87:fb  txqueuelen 1000  (Ethernet)
            RX packets 23068  bytes 14045959 (14.0 MB)
            RX errors 0  dropped 23  overruns 0  frame 0
            TX packets 12173  bytes 1273580 (1.2 MB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
            device interrupt 20  memory 0xf7100000-f7120000  

    lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
            inet 127.0.0.1  netmask 255.0.0.0
            inet6 ::1  prefixlen 128  scopeid 0x10<host>
            loop  txqueuelen 1000  (Local Loopback)
            RX packets 144  bytes 13680 (13.6 KB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 144  bytes 13680 (13.6 KB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Step 4: 设置DNS服务

  1. 在基本安装完成后，默认DNS指向的是127.0.0.53:53，无法解析公网域名！！！
    解决办法：停止并禁用系统默认的DNS服务systemd-resolved，并删除/etc/resolv.conf软连接

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    root@nuc5i3:~# ping t.cn
    ping: t.cn: Temporary failure in name resolution

    root@nuc5i3:~# netstat -tunpl
    Active Internet connections (only servers)
    Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
    tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      1001/systemd-resolv
    tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      2012/sshd
    tcp6       0      0 :::22                   :::*                    LISTEN      2012/sshd
    udp        0      0 127.0.0.53:53           0.0.0.0:*                           1001/systemd-resolv

    root@nuc5i3:~# systemctl stop systemd-resolved
    root@nuc5i3:~# systemctl disable systemd-resolved
    root@nuc5i3:~# systemctl status systemd-resolved
    ● systemd-resolved.service - Network Name Resolution
    Loaded: loaded (/lib/systemd/system/systemd-resolved.service; disabled; vendor preset: enabled)
    Active: inactive (dead)
        Docs: man:systemd-resolved.service(8)
            https://www.freedesktop.org/wiki/Software/systemd/resolved
            https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers
            https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients

    root@nuc5i3:/# ls -l /etc/resolv.conf
    lrwxrwxrwx 1 root root 39 Feb  3 18:22 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

    root@nuc5i3:/# rm /etc/resolv.conf

  2. 重新创建文件/etc/resolv.conf，并写入自定义的nameserver

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    root@nuc5i3:~# cat /etc/resolv.conf
    nameserver 192.168.0.1
    nameserver 8.8.8.8

  3. 简单用dig测试一下，DNS现在正常工作了。

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    root@nuc5i3:~# dig t.cn

    ; <<>> DiG 9.11.3-1ubuntu1.11-Ubuntu <<>> t.cn
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22813
    ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

    ;; OPT PSEUDOSECTION:
    ; EDNS: version: 0, flags:; udp: 512
    ;; QUESTION SECTION:
    ;t.cn.    IN  A

    ;; ANSWER SECTION:
    t.cn.    59  IN  A  116.211.169.137

    ;; Query time: 197 msec
    ;; SERVER: 8.8.8.8#53(8.8.8.8)
    ;; WHEN: Sat Jun 20 13:05:06 UTC 2020
    ;; MSG SIZE  rcvd: 49

Step 5: 设置Wifi网络接入（可选）

  1. 在确认已连接公网、且DNS正常工作的前提下，在线安装network-manager（其中包括了无线网卡驱动程序等必需的软件包）

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    # apt update
    # apt install network-manager

    注意：如果有线网卡没有配置nameserver，而且缺少上一步强行设置nameserver的情况下，由于不能正确解析公网域名，apt无法工作！！！

  2. 再次编辑/etc/netplan/50-cloud-init.yaml，至少需要配置Access-points的SSID和接入密码等。
    注意：必须显示定义渲染方式为NetworkManager，这也是上一步需要apt安装的原因。

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    # This file is generated from information provided by the datasource.  Changes
    # to it will not persist across an instance reboot.  To disable cloud-init's
    # network configuration capabilities, write a file
    # /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
    # network: {config: disabled}
    network:
        version: 2
        renderer: NetworkManager

        ethernets:
            enp0s25:
                dhcp4: no
                addresses: [192.168.0.130/24]
                gateway4: 192.168.0.1

        wifis:
            wlp2s0:
                access-points:
                    "NETGEAR59":
                        password: "xxxxxxxx"
                dhcp4: no
                addresses: [192.168.0.131/24]
                gateway4: 192.168.0.1

  3. 再次netplan generate检查并刷新网络配置，netplan apply启动无线网卡。
    检查网络状态，ifconfig确认无线网卡wlp2s0启动成功
    注意：netplan有中间配置文件的刷新机制，generate + apply是一个良好的操作习惯。

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    root@nuc5i3:/etc/netplan# netplan generate
    root@nuc5i3:/etc/netplan# netplan apply
    root@nuc5i3:/etc# ifconfig
    ......
    wlp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.0.131  netmask 255.255.255.0  broadcast 192.168.0.255
            inet6 fe80::3613:e8ff:fe25:20d8  prefixlen 64  scopeid 0x20<link>
            ether 34:13:e8:25:20:d8  txqueuelen 1000  (Ethernet)
            RX packets 501  bytes 94281 (94.2 KB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 44  bytes 4436 (4.4 KB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

附录： 如何查看网卡的逻辑设备名

不同型号的硬件设备，由于其驱动程序的差异，在Ubuntu安装完成后会有不同的设备名。

使用lshw命令，可以查询全部硬件设备信息，并找到其逻辑设备名。

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# lshw
nuc5i3
    description: Desktop Computer
    width: 64 bits
    capabilities: smbios-2.8 dmi-2.8 smp vsyscall32
    configuration: boot=normal chassis=desktop uuid=00EC2C62-7872-E311-B04F-B8AEED7387FB
......
        *-network
             description: Ethernet interface
             product: Ethernet Connection (3) I218-V
             vendor: Intel Corporation
             physical id: 19
             bus info: pci@0000:00:19.0
             logical name: enp0s25
             version: 03
             serial: b8:ae:ed:73:87:fb
             size: 100Mbit/s
             capacity: 1Gbit/s
             width: 32 bits
             clock: 33MHz
......
        *-network
            description: Wireless interface
            product: Wireless 7265
            vendor: Intel Corporation
            physical id: 0
            bus info: pci@0000:02:00.0
            logical name: wlp2s0
            version: 59
            serial: 34:13:e8:25:20:d8
            width: 64 bits
            clock: 33MHz
......

还有一个办法，就是命令ip a查看网卡的简要信息。

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root@nuc5i3:~# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enp0s25: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether b8:ae:ed:73:87:fb brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.130/24 brd 192.168.0.255 scope global enp0s25
       valid_lft forever preferred_lft forever
    inet6 fe80::baae:edff:fe73:87fb/64 scope link
       valid_lft forever preferred_lft forever
3: wlp2s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 34:13:e8:25:20:d8 brd ff:ff:ff:ff:ff:ff