目錄表

Ubuntu 18/20/22 相關設定整理

Ubuntu 18/20/22 相關設定整理

了解主機現況配置

CPU核心數 / 記憶體大小 / 硬碟空間 / 作業系統版本

lscpu
free -h
lsblk
lsb_release -a

替代方案

cat /proc/cpuinfo | grep processor | wc -l
cat /proc/meminfo | grep MemTotal
df -h /
cat /etc/issue

網路相關

curl https://ip.im
sudo ufw status
ip a
ip r
ip link show
cat /etc/resolv.conf | grep nameserver
tracepath -n 1.1.1.1

網路 IP 設定

參考

Exp. 更改 IP 設定為 192.168.11.204

sudo vi /etc/netplan/00-installer-config.yaml

network:
  ethernets:
    ens18:
      addresses: [192.168.11.204/24]
      gateway4: 192.168.11.1
      nameservers:
        addresses: [8.8.8.8,8.8.4.4]
      dhcp4: no
  version: 2

Exp. 兩張網卡指定 default route 為 eth0

sudo vi /etc/netplan/00-installer-config.yaml

network:
  ethernets:
    eth0:
      dhcp4: true
    eth1:
      addresses: [192.168.7.101/24]
      routes:
        - to: 192.168.7.0/24
          via: 192.168.7.1
          metric: 40
          table: 200
      nameservers:
         addresses: [8.8.8.8,168.95.192.1]
      dhcp4: no
  version: 2

localadmin@iiidevops-1:~$ ip route
default via 172.17.13.177 dev eth0 proto dhcp src 172.17.13.189 metric 100
172.17.13.176/28 dev eth0 proto kernel scope link src 172.17.13.189
172.17.13.177 dev eth0 proto dhcp scope link src 172.17.13.189 metric 100
192.168.7.0/24 dev eth1 proto kernel scope link src 192.168.7.101

可以透過 sudo netplan apply 立即生效或是 sudo reboot 重新開機後生效

設定 ufw 主機防火牆

Exp. 設定開啟 tcp port 22(ssh), 80(http), 443(https) 以及 udp port 161(snmp)

ufw allow proto tcp from any to any port 22,80,443 comment 'Open SSH/Web ports'
ufw allow proto udp from any to any port 161 comment 'Open SNMP ports'

設定後查看目前 ufw 狀態

ufw status

看執行結果

~# ufw status
Status: active

To                         Action      From
--                         ------      ----
22/tcp                     ALLOW       Anywhere
22,80,443/tcp              ALLOW       Anywhere                   # Open SSH/Web ports
161/udp                    ALLOW       Anywhere                   # Open SNMP ports
22/tcp (v6)                ALLOW       Anywhere (v6)
22,80,443/tcp (v6)         ALLOW       Anywhere (v6)              # Open SSH/Web ports
161/udp (v6)               ALLOW       Anywhere (v6)              # Open SNMP ports

修改 iptables 規則, 重開機仍能自動生效

參考 - https://askubuntu.com/questions/1452706/problem-with-my-iptables-configuration-on-reboot/1452833#1452833
需要安裝 iptables-persistent 套件
```
apt install iptables-persistent -y
```

修改 iptables 規則 Exp.

iptables -I FORWARD -i br0 -p all -j ACCEPT

將修改後的規則寫入 /etc/iptables/rules.v4
```
iptables-save -c > /etc/iptables/rules.v4
```

更改 hostname (一)

參考 - https://www.itread01.com/content/1541622152.html

先 /etc/cloud/cloud.cfg 內 preserve_hostname 為 true

sudo vi /etc/cloud/cloud.cfg

:
preserve_hostname: true
:

執行 hostnamectl 設定 hostname Exp. 更改為 pve-devops1
```
sudo hostnamectl set-hostname pve-devops1
```

更改 hostname (二)

Exp. 設定 hostname 為 iServStorM1

sudo su -
vi /etc/hosts

127.0.0.1       localhost
127.0.1.1       iServStorM1
:

vi /etc/hostname

iServStorM1

hostname -F /etc/hostname

參考網址 -
- http://computer.jges.mlc.edu.tw/index.php/ubuntu/112-ubuntu-14-04-%E8%A8%AD%E5%AE%9Ahostname

建立使用者命令

參考 - https://www.cyberciti.biz/faq/create-a-user-account-on-ubuntu-linux/

Exp. 建立 localadmin

sudo useradd -s /bin/bash -d /home/localadmin/ -m -G sudo localadmin
sudo passwd localadmin

如果useradd 建立時沒提供 sudo 權限可以之後透過 usermod 來處理 Exp.
```
sudo usermod -aG sudo localadmin
```

查詢安裝套件檔案路徑

參考網址 - https://www.ubuntu-tw.org/modules/newbb/viewtopic.php?post_id=81494

語法 : dpkg -L 套件名稱 Exp. docker

/# dpkg -L docker
/.
/usr
/usr/share
/usr/share/doc
/usr/share/doc/docker
/usr/share/doc/docker/changelog.Debian.gz
/usr/share/doc/docker/copyright

Server 版安裝圖形操作介面

sudo apt-get install --no-install-recommends ubuntu-desktop

參考網址 -
- http://www.arthurtoday.com/2012/11/ubuntu-server-install-unity-gui.html

清除系統檔案空間

System Journal Logs Ref - https://ubuntuhandbook.org/index.php/2020/12/clear-systemd-journal-logs-ubuntu/

查看目前已使用空間

root@demo-77:/var/log/journal/4ad9885bb19142118fd758b3be95057e# journalctl --disk-usage
Archived and active journals take up 4.0G in the file system.

即時清除保留兩天

root@demo-77:/var/log/journal/4ad9885bb19142118fd758b3be95057e# journalctl --rotate
root@demo-77:/var/log/journal/4ad9885bb19142118fd758b3be95057e# journalctl --vacuum-time=2days
:
root@demo-77:/var/log/journal/4ad9885bb19142118fd758b3be95057e# journalctl --disk-usage
Archived and active journals take up 16.0M in the file system.

設定最多使用空間 Exp. 500M

vi /etc/systemd/journald.conf

:
[Journal]
:
SystemMaxUse=500M
:

systemctl daemon-reload

清理現有的大型 journal 檔案

sudo journalctl --vacuum-size=500M

VMWare 內出現的 multipathd 異常訊息

參考 - https://askubuntu.com/questions/1242731/ubuntu-20-04-multipath-configuration

在 VMWare 內建立 Ubuntu 20.04 的 VM , 在 /var/log/syslog 會看到以下的異常訊息

~# tail -f /var/log/syslog
Aug 31 10:43:07 iiidevops4 multipathd[747]: sda: add missing path
Aug 31 10:43:09 iiidevops4 multipathd[747]: sda: failed to get udev uid: Invalid argument
Aug 31 10:43:11 iiidevops4 multipathd[747]: sda: failed to get sysfs uid: Invalid argument
Aug 31 10:43:12 iiidevops4 multipathd[747]: sda: failed to get sgio uid: No such file or directory
Aug 31 10:43:17 iiidevops4 multipathd[747]: sda: add missing path

解決方式 :

vi /etc/multipath.conf

defaults {
    user_friendly_names yes
}
blacklist {
    devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st|sda)[0-9]*"
}

systemctl restart multipath-tools

安裝呈現即時網路連線流量工具

參考 - https://askubuntu.com/questions/257263/how-to-display-network-traffic-in-the-terminal
直接安裝 bmon, slurm, tcptrack 其中一套或都安裝
安裝語法
```
sudo apt install bmon slurm tcptrack
```

ubuntu