Just after the installation of operating systems, you must configure the network to access your system from outside. This guide helps you to Configure IP Address in CentOS 7 / RHEL 7 & CentOS 6 / RHEL 6.
Here I will show how to configure Static IP addresses for your machine and also configure the network interface to get an IP address from the DHCP server.
Prerequisites
Let’s check the available interfaces on our system. Use the ifconfig command to list interfaces.
ifconfig
Output:
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 2406:7400:bf:7cdd:e387:a515:14c9:2272 prefixlen 64 scopeid 0x0
inet6 2406:7400:bf:e32d:8706:45ed:f7dd:cda8 prefixlen 64 scopeid 0x0
inet6 fe80::9cf2:e3d2:e192:8273 prefixlen 64 scopeid 0x20
ether 08:00:27:13:2c:70 txqueuelen 1000 (Ethernet)
RX packets 663 bytes 62963 (61.4 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 754 bytes 80123 (78.2 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10
loop txqueuelen 1000 (Local Loopback)
RX packets 64 bytes 5632 (5.5 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 64 bytes 5632 (5.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
From the above output, you can see my system has two interfaces namely lo and ifcfg-enp0s3. Depends on hardware, the name of the interface will change.
To set an IP address to an interface, go to /etc/sysconfig/network-scripts/ directory, there you will find a file ifcfg-<interfacename>.
cd /etc/sysconfig/network-scripts/ ; ls -al ifcfg-*
Output:
-rw-r--r--. 1 root root 376 Nov 24 03:05 ifcfg-enp0s3 -rw-r--r--. 1 root root 254 Mar 29 2019 ifcfg-lo
As per the above output, my system has a file ifcfg-enp0s3 since CentOS 7 / RHEL 7 uses consistent network interface naming.
Static IP Address
In this mode, we will manually assign an IP address to machines.
cd /etc/sysconfig/network-scripts/
Edit the ifcfg-<interfacename> file.
vi ifcfg-enp0s3
FROM
HWADDR=00:0C:29:76:96:A8 TYPE=Ethernet BOOTPROTO=dhcp DEFROUTE=yes PEERDNS=yes PEERROUTES=yes IPV4_FAILURE_FATAL=no IPV6INIT=yes IPV6_AUTOCONF=yes IPV6_DEFROUTE=yes IPV6_PEERDNS=yes IPV6_PEERROUTES=yes IPV6_FAILURE_FATAL=no NAME=eno16777736 UUID=e5a5d8e9-b5d4-4b5e-bd1e-6ebcd0144dfa ONBOOT=no
TO
TYPE="Ethernet" PROXY_METHOD="none" BROWSER_ONLY="no" BOOTPROTO="none" # Static IP DEFROUTE="yes" IPV4_FAILURE_FATAL="no" IPV6INIT="yes" IPV6_AUTOCONF="yes" IPV6_DEFROUTE="yes" IPV6_FAILURE_FATAL="no" IPV6_ADDR_GEN_MODE="stable-privacy" NAME="enp0s3" DEVICE="enp0s3" ONBOOT="yes" # Enable Network Interaface on boot IPADDR="192.168.0.10" # IP Address NETMASK="255.255.255.0" # NetMask GATEWAY="192.168.0.1" # Gateway / Router DNS1="192.168.0.1" # DNS Server 1 DNS2="8.8.8.8" # DNS Server 2 IPV6_PRIVACY="no"
Restart the network service using the below command.
service network restart
Now you can see the ip address 192.168.0.10 assigned to the interface enp0s3.
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.0.10 netmask 255.255.255.0 broadcast 192.168.0.255
inet6 2406:7400:bf:7cdd:e387:a515:14c9:2272 prefixlen 64 scopeid 0x0
inet6 fe80::9cf2:e3d2:e192:8273 prefixlen 64 scopeid 0x20
ether 08:00:27:13:2c:70 txqueuelen 1000 (Ethernet)
RX packets 1001 bytes 95433 (93.1 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1055 bytes 136959 (133.7 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10
loop txqueuelen 1000 (Local Loopback)
RX packets 64 bytes 5632 (5.5 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 64 bytes 5632 (5.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
DHCP IP Address
In this mode, the system will get an IP address from the DHCP server. This is the default mode set on CentOS to get an IP address from the DHCP server.
cd /etc/sysconfig/network-scripts/
Edit the ifcfg-<interfacename> file.
vi ifcfg-enp0s3
Just modify the lines like this.
TYPE="Ethernet" PROXY_METHOD="none" BROWSER_ONLY="no" BOOTPROTO="dhcp" # DHCP IP DEFROUTE="yes" IPV4_FAILURE_FATAL="no" IPV6INIT="yes" IPV6_AUTOCONF="yes" IPV6_DEFROUTE="yes" IPV6_FAILURE_FATAL="no" IPV6_ADDR_GEN_MODE="stable-privacy" NAME="enp0s3" DEVICE="enp0s3" ONBOOT="yes" # Enable Network Interface on boot IPV6_PRIVACY="no"
Restart the network service using the below command.
service network restart
Now you can see the ip address 192.168.0.23 assigned to the interface enp0s3 using DHCP.
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.0.23 netmask 255.255.255.0 broadcast 192.168.0.255
inet6 2406:7400:bf:7cdd:e387:a515:14c9:2272 prefixlen 64 scopeid 0x0
inet6 2406:7400:bf:e32d:8706:45ed:f7dd:cda8 prefixlen 64 scopeid 0x0
inet6 fe80::9cf2:e3d2:e192:8273 prefixlen 64 scopeid 0x20
ether 08:00:27:13:2c:70 txqueuelen 1000 (Ethernet)
RX packets 663 bytes 62963 (61.4 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 754 bytes 80123 (78.2 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10
loop txqueuelen 1000 (Local Loopback)
RX packets 64 bytes 5632 (5.5 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 64 bytes 5632 (5.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0Conclusion
That’s All. Please share your feedback in the comments section.