How to Configure the Network as DHCP in a Linux Image -

Overview

Create a custom image by using ECS or OSS import. If the network configuration in the image is a static IP address, you need to modify network interface controller attribute to DHCP to ensure that you can dynamically obtain the IP address when you create a new ECS instance by using the image. This topic describes how to configure mainstream Linux operating systems.

Error message

Different Linux operating systems can be used to configure the network as DHCP in a Linux image as follows:

Redhat series

The supported operating systems are as follows:

CentOS 6/7/8
Red Hat 6/7/8/9
Anolis 7/8
Fedora 33/34/35
Alibaba Cloud Linux 2/3
CentOS Stream
Rocky Linux
AlmaLinux

To connect the AD domain to the LDAP service, perform the following steps:

Connect to an ECS instance. For more information about how to connect to an ECS instance, see Use password or key authentication to log on to a Linux instance.
Run the following command to edit the network configuration file:
```
vi /etc/sysconfig/network-scripts/ifcfg-eth0 
```

Modify the following network configuration items.

BOOTPROTO=dhcp
DEVICE=eth0
ONBOOT=yes
STARTMODE=auto
TYPE=Ethernet
USERCTL=no

Press the Esc key, enter the :wq, and press Enter to save and exit the file editing.
Restart the network service.
- For CentOS 6 and Red Hat 6 operating systems, run the following command:
```
service network restart
```
- For CentOS 7, Red Hat 7, Anolis 7, and Alibaba Cloud Linux 2 operating systems, run the following command:
```
systemctl restart network
```
- Anolis 8, fedora 33/34/35, CentOS 8 and Red Hat 8 Alibaba Cloud Linux 3 operating systems, perform the following operations:
  1. Run the following command to reload all network interface controller configurations:
```
 nmcli c reload
```
  2. Run the following command to activate network interface controller:
```
nmcli d connect eth0
```

Debian series

Supported operating systems are as follows:

Ubuntu 14/16
Debian /8/9/10/11
Ubuntu 18/20

To configure Ubuntu 14/16 and Debian /8/9/10/11 operating systems, perform the following operations:

Connect to the ECS instance and run the following command to open the network configuration file.
```
vim /etc/network/interfaces
```
Modify the following network configuration items.
```
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp
```
Note:
- auto eth0 :eth0 indicates that the alias of network interface controller of the ifconfig output pair on your own machine matches.
- iface eth0 inet dhcp: indicates that the IP address acquisition method is DHCP.
Press the Esc key, enter the :wq, and press Enter to save and exit the file editing.
Run the following command to restart the network service:
```
service networking restart
```
or
```
systemctl restart networking
```
Note :Ubuntu 14 does not apply to the preceding two commands. You can run the reboot command to restart the instance.

Configure the Ubuntu 18/20 operating system as follows:

Connect to the ECS instance and run the following command to open the network configuration file.
```
vim  /etc/netplan/99-eth0.yaml
```

Add the following network interface controller configurations.

network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      dhcp4: yes
      dhcp6: no

Press the Esc key, enter the :wq, and press Enter to save and exit the file editing.
Run the netplan apply command to make the configuration take effect.

SLES series

Supported operating systems are as follows:

SUSE 11/12/15
OpenSUSE 42/15

Connect to the ECS instance and run the following command to edit the network configuration file:
```
vi /etc/sysconfig/network/ifcfg-eth0
```
Modify the following network configuration items.
```
BOOTPROTO='dhcp'
STARTMODE='auto'
```
After the configuration is complete, run the following command to restart the network service.
```
systemctl restart wicked
```

References

The names of network services in different Linux and versions and the commands to restart network services are as follows:

OS	Version	Network service name	Restart network service commands
CentOS	6	network	service network restart
	7	network	systemctl restart network
	8	NetworkManager	systemctl restart NetworkManager
Debian	8	networking	systemctl restart networking
	9	networking	systemctl restart networking
	10	networking	systemctl restart networking
Ubuntu	14	networking	service networking restart
	16	networking	systemctl restart networking
	18	systemd-networkd	systemctl restart systemd-networkd
	20	systemd-networkd	systemctl restart systemd-networkd
Sles	15	wicked	systemctl restart wicked
Sles	12	wicked	systemctl restart wicked
Opensuse	15	wicked	systemctl restart wicked
Aliyun Linux 2	2	systemd-networkd	systemctl restart systemd-networkd

：How to Configure the Network as DHCP in a Linux Image