How to setup network in centos 6

Setup network in centos 6 :

By default Centos 6 new installation will not have network access , which means you need to configure ip address to the network interfaces by yourself.

In this article we can see how to setup network in centos 6 , i.e. assigning ipaddress in static and in DHCP  mode .

» DHCP mode :

Assigning ip address in DHCP mode

Step 1 » Check the network interface name by typing below command
[root@leela ~]# ip a
1: lo: mtu 16436 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
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: p4p1: mtu 1500 qdisc mq state UP qlen 1000
link/ether 00:22:19:09:4d:3c brd ff:ff:ff:ff:ff:ff
Here “lo” is the loopback interface and “p4p1” is the network interface that you need to configure .

Step 2 » you can see the file named ifcfg-p4p1 ( Interface name ) in the location “/etc/sysconfig/network-scripts/” , open the file and you can see the lines as below

DEVICE="p4p1"
HWADDR="00:22:19:09:4D:3C"
NM_CONTROLLED="yes"
ONBOOT="no"

Just modify the lines like this

DEVICE="p4p1"
HWADDR="00:22:19:09:4D:3C"
NM_CONTROLLED="yes"
ONBOOT="yes"    # Interface enabled
BOOTPROTO="dhcp"  #Assigning IP from DHCP

Step 3 » Start the network service and you can see the status as below .
[root@leela ~]# service network start
Bringing up loopback interface:                [  OK  ]
Bringing up interface p4p1:
Determining IP information for p4p1... done.   [  OK  ]
Step 4 » Now you can see the ip address “192.168.1.12” assigned to the interface p4p1 using dhcp .
[root@leela ~]# ip a
1: lo: mtu 16436 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
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: p4p1: mtu 1500 qdisc mq state UP qlen 1000
link/ether 00:22:19:09:4d:3c brd ff:ff:ff:ff:ff:ff
inet 192.168.1.12/26 brd 172.27.6.63 scope global p4p1
    inet6 fe80::222:19ff:fe09:4b3c/64 scope link
       valid_lft forever preferred_lft forever

» Static mode :

Assigning ip address in Static mode

Step 1 » Check the network interface name by typing below command
[root@leela ~]# ip a
1: lo: mtu 16436 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
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: p4p1: mtu 1500 qdisc mq state UP qlen 1000
link/ether 00:22:19:09:4d:3c brd ff:ff:ff:ff:ff:ff
Here “lo” is the loopback interface and “p4p1” is the network interface that you need to configure .

Step 2 » you can see the file named ifcfg-p4p1 ( Interface name ) in the location “/etc/sysconfig/network-scripts/” , open the file and you can see the lines as below

DEVICE="p4p1"
HWADDR="00:22:19:09:4D:3C"
NM_CONTROLLED="yes"
ONBOOT="no"

Just modify the lines like this

DEVICE="p4p1"
HWADDR="00:22:19:09:4D:3C"
NM_CONTROLLED="yes"
ONBOOT="yes"    # Interface enabled
BOOTPROTO="static"  #Assigning in static mode 
IPADDR=192.168.1.11 #IP address
NETMASK=255.255.255.0 # Subnet Mask
GATEWAY=192.168.1.1 # Default Gateway
DNS1=8.8.8.8 #Primary DNS
DNS2=4.2.2.2 #Secondary DNS

Step 3 » Start the network service and you can see the status as below .
[root@leela ~]# service network start
Bringing up loopback interface:                [  OK  ]
Bringing up interface p4p1:   [  OK  ]
Step 4 » Now you see the ip address “192.168.1.12” assigned to the interface p4p1  .
[root@leela ~]# ip a
1: lo: mtu 16436 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
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: p4p1: mtu 1500 qdisc mq state UP qlen 1000
link/ether 00:22:19:09:4d:3c brd ff:ff:ff:ff:ff:ff
inet 192.168.1.12/26 brd 172.27.6.63 scope global p4p1
    inet6 fe80::222:19ff:fe09:4b3c/64 scope link
       valid_lft forever preferred_lft forever

Also see

Setup network on ubuntu 18.04