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How to configure network on CentOS 7

To configure network on CentOS 7

Generally after installing CentOS 7 , the network cannot be connected in that machine. These troubleshooting methods helps to setup network on centos 7 in both GUI and Command mode.

To Setup network

To identify ethernet cards in your machine,you can use any of the three commands below
nmcli d (or) ifconfig (or) ip a,Here we are using “ nmcli d”
Type " nmcli d" in your terminal

Output

[root@linuxhelp ~]$ nmcli  d
DEVICE          TYPE          STATE             CONNECTION 
eno16777736     ethernet      disconnected          --         
lo               loopback unmanaged             --

To setup network in GUI mode

Type “ nmtui” to open Network manager and then edit a connection

Available network interface will be displayed

To configure DHCP

1. Move the highlighter to the IPv4 CONFIGURATION and press enter
2. Choose “ Automatic” from the list
3. Choose Automatic Connect check box.
4. Press OK and quit Network manager.

To Restart network service

[root@linuxhelp ~]# systemctl restart network


The server gets the IP address from DHCP server

Static configuration For Manual IP address

1. Choose “ Manual” in IPv4 CONFIGURATION.
2. Add IP Address with Subnet , Gateway and DNS server ( Refer below image ).
3. Choose Automatic Connect check box.
4. Press OK and quit Network manager.


To restart network service

[root@linuxhelp ~]# systemctl restart network

In Command mode

In command line interface mode network can be set by editing the configuration file in the following path.

[root@linuxhelp ~]$ vim /etc/sysconfig/network-scripts/ifcfg-eno16777736
TYPE=Ethernet
BOOTPROTO=none
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
NAME=eno16777736
UUID=1edfad82-a530-4b13-8839-e985423c22b7
ONBOOT=no
HWADDR=00:0C:29:3D:1D:D9
PEERDNS=yes
PEERROUTES=yes
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes

For DHCP configuration

Edit only the below mentioned two configuration
BOOTPROTO,ONBOOT
and replace it with
BOOTPROTO=dhcp
ONBOOT=yes

Now restart the network service through command line

[root@linuxhelp ~]# systemctl restart network

For Static Configuration
Edit the below configuration and also add some more configurations

BOOTPROTO=none
ONBOOT=no 
replace with
BOOTPROTO=static
ONBOOT=yes

Now restart the network service through command line

[root@linuxhelp ~]# systemctl restart network


Now you can check ip using ip a command

[root@linuxhelp Desktop]# ip a
1: lo: < LOOPBACK,UP,LOWER_UP>  mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno16777736: < BROADCAST,MULTICAST,UP,LOWER_UP>  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:3d:1d:d9 brd ff:ff:ff:ff:ff:ff
    inet 192.168.5.67/24 brd 192.168.5.255 scope global eno16777736
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe3d:1dd9/64 scope link 
       valid_lft forever preferred_lft forever

If you just want to edit the hostname, edit the hostname file in the following path

[root@linuxhelp Desktop]# vim /etc/hostname

Tag : CentOS
FAQ
Q
where do we set nameserver
A
/etc/resolve.conf
Q
anyother command to set network otherthan nmcli
A
nmtui
Q
I have set ipaddr manually in ifcfg file and restart network service . But I didn't get ipaddr . Because I didn't get any internet. Pls, help me with this issue
A
use ifup interface_name (or) nmcli conneection up interface_name
Q
I use nmcli , but shows command not found
A
check NetworkManager for properly . Start the NetworkManager and then try
Q
every time I restart , network goes down , is there any option network automatically starts when we start a machine. I already enable network service
A
IN /etc/sysconfig/network-scripts/ifcfg-interface_name change to onboot=yes