What do I do if the IP address of a Linux instance in the NIC configuration file is different from the IP address of the instance displayed in the ECS console? -

A static IP address in the NIC configuration file that differs from the ECS console can cause network failures, ineffective security group rules, and management issues. Update the NIC configuration to match the console IP address.

Problem description

The static IP address in the NIC configuration file does not match the IP address shown in the ECS console.

Solution

Step 1: Obtain the IP address from the ECS console

Find the private IP address of the instance in the ECS console. See IP addresses.

Step 2: Update the NIC configuration file

Red Hat Enterprise Linux (RHEL) series

Note

Applies to: Alibaba Cloud Linux 2, Alibaba Cloud Linux 3, CentOS 6, CentOS 7, CentOS 8, Red Hat 6, Red Hat 7, Red Hat 8, Red Hat 9, Anolis 7, Anolis 8, Fedora 33, Fedora 34, and Fedora 35.
This example uses Alibaba Cloud Linux 3.2.
This example uses the primary NIC eth0. Replace with your actual NIC name.

Connect to the instance.

See Log on to a Linux instance using Workbench.
View the subnet mask.

View the routing information:
```
route -n
```
Sample output:
- The subnet mask (Genmask) is 255.255.255.0.
- The default gateway (Gateway) is 192.168.1.253.

Modify or create the NIC configuration file:

sudo vi /etc/sysconfig/network-scripts/ifcfg-eth0

Set the IP acquisition method to Static and configure the primary private IPv4 address and subnet mask.

Template:

DEVICE=eth0
TYPE=Ethernet
#The method used to obtain an IP address, which is set to Static.
BOOTPROTO=static 

#The IPv4 address and subnet mask that require manual configuration.
IPADDR=<Replace the value of this parameter with the actual IPv4 address>
NETMASK=<Replace the value of this parameter with the actual subnet mask>

Example:

DEVICE=eth0
TYPE=Ethernet
#The method used to obtain an IP address, which is set to Static.
BOOTPROTO=static 

#The IPv4 address and subnet mask that require manual configuration.
IPADDR=192.168.1.201
NETMASK=255.255.255.0

Ubuntu 22, Ubuntu 24, and Debian 12

Connect to the instance.

See Log on to a Linux instance using Workbench.
View the subnet mask.

View the routing information:
```
route -n
```
Sample output:
- The subnet mask (Genmask) is 255.255.255.0.
- The default gateway (Gateway) is 192.168.1.253.
Disable the network configuration feature of cloud-init:

Important
The /etc/netplan/50-cloud-init.yaml file is auto-generated by cloud-init at instance startup. Disable cloud-init network configuration before editing this file. See cloud-init network initialization.
```
sudo vim /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg
```
Add the following content:
```
network: {config: disabled}
```

Open the /etc/netplan/50-cloud-init.yaml file and configure the NIC:

sudo vim /etc/netplan/50-cloud-init.yaml

Example:

network:
    version: 2
    ethernets:
        eth0: #The name of the NIC.
            dhcp4: false #By default, Dynamic Host Configuration Protocol (DHCP) is enabled to automatically assign IP addresses. If you set this parameter to false, you must manually configure IP addresses for the NIC.
            match:
                macaddress: 00:16:3e:16:43:xx #Replace the value of this parameter with the actual MAC address of the NIC.
            set-name: eth0
            addresses:
                    - 192.168.1.201/24 #Replace the value of this parameter with the actual primary private IPv4 address of the NIC.
            routes:
              - to: default
                via: 192.168.1.253 #Replace the value of this parameter with the actual default gateway address.

Ubuntu 18 and Ubuntu 18 20

Connect to the instance.

See Log on to a Linux instance using Workbench.
View the subnet mask.

View the routing information:
```
route -n
```
Sample output:
- The subnet mask (Genmask) is 255.255.255.0.
- The default gateway (Gateway) is 192.168.1.253.
Disable the network configuration feature of cloud-init:

Important
The /etc/netplan/50-cloud-init.yaml file is auto-generated by cloud-init at instance startup. Disable cloud-init network configuration before editing this file. See cloud-init network initialization.
```
sudo vim /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg
```
Add the following content:
```
network: {config: disabled}
```

Open the /etc/netplan/50-cloud-init.yaml file and configure the NIC:

sudo vim /etc/netplan/50-cloud-init.yaml

Example:

network:
    version: 2
    ethernets:
        eth0: #The name of the NIC.
            dhcp4: false #By default, DHCP is enabled to automatically assign IP addresses. If you set this parameter to false, you must manually configure IP addresses for the NIC.
            match:
                macaddress: 00:16:3e:16:43:xx #Replace the value of this parameter with the actual MAC address of the NIC.
            set-name: eth0
            addresses:
                    - 192.168.1.201/24 #Replace the value of this parameter with the actual primary private IPv4 address of the NIC.
            gateway4: 192.168.1.253 #Replace the value of this parameter with the actual default gateway address.

Step 3: Restart the network service

Restart the network service to apply the new configuration.

Important

Some commands require an instance restart, which may cause service interruptions. Restart the network service during off-peak hours.

Operating system	Restart command
Alibaba Cloud Linux 2 CentOS 7 Red Hat 7 Anolis 7 SUSE Linux 11, SUSE Linux 12, and SUSE Linux 15 openSUSE 15 and openSUSE 42	`sudo service network restart` or `sudo systemctl restart network`
CentOS 6 Red Hat 6	`sudo service network restart`
Alibaba Cloud Linux 3 CentOS 8 Red Hat 8 Anolis 8 Fedora 33, Fedora 34, and Fedora 35	`sudo systemctl restart NetworkManager` or `sudo reboot`
Ubuntu 18, Ubuntu 20, and Ubuntu 22 Debian 12	`sudo netplan apply`
Ubuntu 14 and Ubuntu 16 Debian 8, Debian 9, Debian 10, and Debian 11	`sudo systemctl restart networking` or `sudo reboot`