Configure a static IP for a Linux ECS instance - - Alibaba Cloud Documentation Center

This topic explains how to configure a static IP address for a Linux ECS instance.

Background

By default, an ECS instance is configured to use Dynamic Host Configuration Protocol (DHCP) mode.

Note

This example uses an ECS instance that runs CentOS 7.6.

Procedure

Step 1: View the IP address and gateway

Log on to the Linux ECS instance. Run the following command to view the IP address and subnet mask of the instance.

ifconfig

The output is similar to the following:

[root@aliyuntest ~]# ifconfig
eth0: flags=4163&lt;UP,BROADCAST,RUNNING,MULTICAST&gt;  mtu 1500
        inet 17.xxx.xxx.xx  netmask 255.255.255.0  broadcast 172.xxx.xxx.x
        ether 00:16:3e:0c:4f:c3  txqueuelen 1000  (Ethernet)
        RX packets 285116  bytes 217057111 (207.0 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 143703  bytes 40663281 (38.7 MiB)
        TX errors 0  dropped 0  overruns 0  carrier 0  collisions 0
lo: flags=73&lt;UP,LOOPBACK,RUNNING&gt;  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 509  bytes 102908 (100.4 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 509  bytes 102908 (100.4 KiB)
        TX errors 0  dropped 0  overruns 0  carrier 0  collisions 0

Run the following command to view the gateway of the instance.

route -n

The output is similar to the following:

[root@alxxx      : ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         172.xxx.xxx.53  0.0.0.0         UG    0      0        0 eth0
169.xxx.0       0.0.0.0         255.255.0.0     U     1002   0        0 eth0
172.xxx.0       0.0.0.0         255.255.255.0   U     0      0        0 eth0

Alternatively, run the following commands to get the subnet mask, gateway, and IP address from the instance metadata. For more information, see Instance metadata.

curl http://100.100.100.200/latest/meta-data/network/interfaces/macs/[$MAC_ID]/netmask
curl http://100.100.100.200/latest/meta-data/network/interfaces/macs/[$MAC_ID]/gateway
curl http://100.100.100.200/latest/meta-data/network/interfaces/macs/[$MAC_ID]/private-ipv4s

The output is similar to the following:

[root@aliyuntest ~]# curl http://100.100.100.200/latest/meta-data/network/interfaces/macs/00:16:3e:0c:4f:c3/netmask
255.255.255.0[root@aliyuntest ~]#
[root@aliyuntest ~]# curl http://100.100.100.200/latest/meta-data/network/interfaces/macs/00:16:3e:0c:4f:c3/gateway
172.xxx.xxx[root@aliyuntest ~]#
[root@aliyuntest ~]# curl http://100.100.100.200/latest/meta-data/network/interfaces/macs/00:16:3e:0c:4f:c3/private-ipv4s
["172.xxx.xxx.0"][root@aliyuntest ~]#
[root@aliyuntest ~]#

Note

Replace [$MAC_ID] with the MAC address of your ECS instance.

Step 2: Change the network type to static

Run the following command to edit the configuration file. Set BOOTPROTO to static, and add the IP address, gateway, and subnet mask that you recorded in the previous step.
```
vim /etc/sysconfig/network-scripts/ifcfg-eth0
```
Example:
```
DEVICE=eth0
BOOTPROTO=static
ONBOOT=yes
IPADDR=172.xxx.xxx
GATEWAY=17x.xxx.253
NETMASK=255.255.255.0
```
Enter :wq and press Enter to save and exit.
Run the following command to restart the network service.
```
systemctl restart network
```