Ubuntu 20.04 網絡配置

“ubuntu從17.10開始，已放棄在/etc/network/interfaces里固定IP的配置，即使配置也不會生效，而是改成netplan方式 ，配置寫在/etc/netplan/01-netcfg.yaml或者類似名稱的yaml文件里”

但DNS配置最好檢查一下17.10以前的傳統配置方法

 

 

 

 

 

 

翻譯自https://linuxhint.com/ubuntu_20-04_network_configuration/

Whether you are a Linux administrator or regular user, you must know the basics of network configuration in your Linux system. it might be helpful when troubleshooting the issues with internal and external connectivity. The basic knowledge involves knowing the interface name, the current IP configuration, and the hostname. Also, you should know how to change the default configurations to the customized settings.

In this article, we will explain how to do basic network configuration in the Ubuntu system. We will use the command-line Terminal for executing the commands. To open the command line Terminal in Ubuntu, use the Ctrl+Alt+T keyboard shortcut.

In this article, we will be covering how to:

• View current IP address
• Set static IP address             設置靜態IP
• Set the dynamic IP address  設置動態IP
• View current hostname         查看主機名稱
• Change hostname                 修改主機名稱

Note: We have run the commands and procedure mentioned in this article on the Ubuntu 20.04 system.

View Current IP Address

To view the current IP address of your machine, you can use either of the following commands:

$ ip a

Or

$ ip addr

Running either of the above commands will display the IP address information. Note down the name of the interface from the output of the above command.

Set Static IP Address

In the following procedure, we will see how to set up the static IP in a Ubuntu system.

Ubuntu 20.04 uses netplan as a default network manager. The configuration file for the netplan is stored in the /etc/netplan directory. You can find this configuration file listed in the /etc/netplan directory the following command:

$ ls /etc/netplan

The above command will return the name of the configuration file with the .yaml extension, which in my case was 01-network-manager-all.yaml.

Before making any changes to this file, make sure to create a backup copy of it. Use the cp command to do so:

$ sudo cp /etc/netplan/01-network-manager- all.yaml 01-network-manager-all.yaml.bak

Note: You might have a configuration file with the name other than the 01-network-manager-all.yaml. So make sure you use the right configuration file name in the commands.

You can edit the netplan configuration using any text editor. Here we are using the Nano text editor for this purpose.

$ sudo nano /etc/netplan/01-network-manager- all.yaml

Then add the following lines by replacing the interface name, IP address, gateway, and DNS information that fit your networking needs.

network:
version: 2
renderer: NetworkManager
ethernets:
 ens33:
  dhcp4: no
  addresses:
  - 192.168.72.140/24
  gateway4: 192.168.72.2
  nameservers:
   addresses: [8.8.8.8, 8.8.4.4]

Once done, save and close the file.

Now test the new configuration using the following command:

$ sudo netplan try

If it validates the configuration, you will receive the configuration accepted message; otherwise, it rolls back to the previous configuration.
Next, run the following command to apply the new configurations.

$ sudo netplan apply

After this, confirm the IP address of your machine using the following command:

$ ip a

It should reflect the changes you have made.

Set the Dynamic IP Address

In the following procedure, we will see how to configure the interface to receive a dynamic IP address from DHCP. Edit the netplan configuration file using any text editor. Here we are using the Nano text editor for this purpose.

$ sudo nano /etc/netplan/01-network-manager- all.yaml

Then add the following lines by replacing the interface name with your system’s network interface.

network:
 version: 2
 renderer: NetworkManager
 ethernets:
  ens33:
   dhcp4: yes
   addresses: []

Once done, save and close the file.

Now test the new configuration using the following command:

$ sudo netplan try

If it validates the configuration, you will receive the configuration accepted message, otherwise, it rolls back to the previous configuration.

Next, run the following command to apply the new configurations.

$ sudo netplan apply

After this, check the IP address of your machine using the following command:

$ ip a

View Current Hostname

To view the current hostname, you can use either of the following commands:

$ hostnamectl

or

$ hostname

Change Hostname

There are two different ways to change the hostname of the system. To change the hostname of the system, you must be a root user or a standard user with sudo privileges.

Using the Hostnamectl Command

To change the hostname of the system to a new name, use the following command:

$ sudo hostnamectl set-hostname name

Example:

$ sudo hostnamectl set-hostname desktop

This command will change the hostname of the system to “desktop”.

After that, reboot the system and you will see the new hostname assigned to your system.

Using Hostname Command

Hostname command can also be used to change the hostname of the system. Use the following command to change the hostname of the system:

$ sudo hostname name

This command changes the hostname of the system temporarily. To permanently change the hostname, you will need to edit the /etc/hostname and /etc/hosts file.

Use the following command to edit the /etc/hostname file:

$ sudo nano /etc/hostname

Replace the old hostname with the new name, then save and exit the file.

Next, use the following command to edit the /etc/hosts file:

Replace the old hostname with the new name, then save and exit the file.

$ sudo nano /etc/hosts

After that, reboot the system and you will see the new hostname assigned to your system.

Once you are done with basic network configurations, use the ping command to verify the connectivity of your system with other systems on the network and the external network.

$ ping IP-address or domain name

That is all the basics you need to know about network configuration in Ubuntu 20.04 system. Note that if you have multiple network interfaces, you will have to perform IP configurations for each interface. I hope you liked the article!

 

 

How to Check Route Table？
ip route show

davidyin@u20:~$ ip route show

default via 192.168.1.1 dev ens18 proto dhcp src 192.168.1.158 metric 100
192.168.1.0/24 dev ens18 proto kernel scope link src 192.168.1.158
192.168.1.1 dev ens18 proto dhcp scope link src 192.168.1.158 metric 100
davidyin@u20:~$
Other commands I am not using.
Add Static Route

# ip route add 10.10.20.0/24 via 192.168.1.100 dev eth0
Remove Static Route
# ip route del 10.10.20.0/24

Add default gateway
# ip route add default via 192.168.1.100

Add an IP address to a specific interface
# ip addr add 192.168.1.5 dev eth1

Remove an IP address
# ip addr del 192.168.1.5/24 dev eth1

I always like to use a Router to assign a static IP to the network device. I just need to know the MAC address then I can do it at DD-WRT router.

 

Ubuntu20配置值靜態ip時需要修改/etc/netplan下面

轉自https://blog.csdn.net/chaofanjun/article/details/106663662?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromBaidu-1.control&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromBaidu-1.control

1-network-manager-all.yaml這個文件，該文件的原始內容為：

在修改該文件時，先試用ifconfig查看下網卡相關信息，然后再對應修改，修改后的文件內容為：

修改時相應的配置為：

ens33:   #配置的網卡名稱 dhcp4: no #dhcp4關閉 dhcp6: no #dhcp6關閉 addresses: [192.168.147.130/24] #設置本機IP及掩碼 gateway4: 192.168.147.1 #設置網關 nameservers: addresses: [192.168.147.1, 114.114.114.114] #設置DNS

 

有時候在修改該文件時，會碰到無權限修改的情況，這時候使用chmod修改下文件權限即可。
修改完成后，在終端再輸入

sudo netplan apply

此時，在終端中使用ifconfig查看ip時可以發現ip地址已經發生了變化。

 

 轉自https://blog.csdn.net/fansnn/article/details/105930009

 

Ubuntu 20.04修改ip地址

今天在繼續上次的辦公協作平台實驗的時候發現虛擬機因為之前是DHCP的方式獲取的ip地址，而這次虛擬機開機后DHCP獲取的地址變更了，因為網站上已經配置了固定ip地址訪問，導致不能訪問網頁，所以需要修改ip地址為上次獲取的ip地址才能訪問，查了一下ubuntu怎么修改ip地址才發現“ubuntu從17.10開始，已放棄在/etc/network/interfaces里固定IP的配置，即使配置也不會生效，而是改成netplan方式 ，配置寫在/etc/netplan/01-netcfg.yaml或者類似名稱的yaml文件里”
話不多說，直接說netplan怎么修改ip地址

 

使用ifconfig命令查看網卡

ifconfig 

 

修改yaml配置文件

sudo vi /etc/netplan/00-installer-config.yaml network: ethernets: ens33: #配置的網卡的名稱 addresses: [192.168.31.215/24] #配置的靜態ip地址和掩碼 dhcp4: no #關閉DHCP，如果需要打開DHCP則寫yes optional: true gateway4: 192.168.31.1 #網關地址 nameservers: addresses: [192.168.31.1,114.114.114.114] #DNS服務器地址，多個DNS服務器地址需要用英文逗號分隔開 version: 2 renderer: networkd #指定后端采用systemd-networkd或者Network Manager，可不填寫則默認使用systemd-workd 

根據自己的需要配置好之后保存文件

使配置的ip地址生效

sudo netplan apply

好了，使用ifconfig命令查看配置的新ip地址是否生效了吧

注意事項：
1、ip地址和DNS服務器地址需要用[]括起來，但是網關地址不需要
2、注意每個冒號后邊都要先加一個空格
3、注意每一層前邊的縮進，至少比上一層多兩個空格