Network Admin How-To: Centos 7 configuration after Instalation

After installing Centos 7 I found that there are a couple of annoyances with the setup. The first is that ifconfig is not installed and the second is that the network card is called some strange name not eth0 (in my case it was eno16777984)!

I found THIS site which sorted the problems:

1) To change the hostname permanently, edit the following file:

sudo vi /etc/hostname

Here you can simply put the name of your system (in my case, I have assigned it CentOS-7):

After that, edit the hosts file:

sudo vi /etc/hosts

Here add the same name, that you have added in the /etc/hostname file, after 127.0.0.1:

After reboot, it will display the new hostname.

2) After login to the CentOS7 server(minimal installation), you will notice that the system doesn’t have ifconfig command :

Install the net-tools package which will include ifconfig:

sudo yum install net-tools

Try the ifconfig command once again:

3) Change the default network interface name to “eth0”

CentOS7 has a default nic name as “en016…..”, as we can see in above screenshoot. To change it back to the default network device name like “ethX”, edit the grub file:

sudo vi /etc/default/grub

Search for the line “GRUB_CMDLINE_LINUX” and append the following: “net.ifnames=0 biosdevname=0″

Will look like this:

GRUB_CMDLINE_LINUX="rd.lvm.lv=rootvg/usrlv rd.lvm.lv=rootvg/swaplv crashkernel=auto 
vconsole.keymap=usrd.lvm.lv=rootvg/rootlv vconsole.font=latarcyrheb-sun16 rhgb 
quiet net.ifnames=0 biosdevname=0"

Create a new configuration based on the currently running system using grub2-mkconfig command:

sudo grub2-mkconfig -o /boot/grub2/grub.cfg

Rename the interface files by renaming the file “/etc/sysconfig/network-scripts/ifcfg-en01…”

sudo mv /etc/sysconfig/network-scripts/ifcfg-eno16777736 /etc/sysconfig/network-scripts/ifcfg-eth0

Reboot the system:

After reboot, check the interface name:

4) Configure the static ip on the server:

Edit the interface file under /etc/sysconfig/network-scripts/ directory:

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

Here is my ifcfg-eth0 file as a sample, please change it according to your requirement:

DEVICE="eth0"
ONBOOT=yes
BOOTPROTO=static
IPADDR=192.168.250.50
NETMASK=255.255.255.0
GATEWAY=192.168.250.2
DNS1=192.168.250.2

Stop and disable the NetworkManager service, because we don’t need it on the server:

sudo systemctl stop NetworkManager 
sudo systemctl disable NetworkManager

Restart the network service(Be careful, if you are connecting remotely, because you will be disconnected after issue this command):

sudo service network restart

Check the newly assigned static ip:

5) Disable IPv6:

First check that IPv6 is enabled or not:

lsmod | grep -i ipv6

Edit the grub file:

sudo vi /etc/default/grub

Search for the line “GRUB_CMDLINE_LINUX” and add the following at the beginning: “ipv6.disable=1″

Will look like this:

GRUB_CMDLINE_LINUX="ipv6.disable=1 rd.lvm.lv=rootvg/usrlv...

Create a new configuration based on the currently running system using grub2-mkconfig command:

sudo grub2-mkconfig -o /boot/grub2/grub.cfg

Reboot the system:

Once again, check the IPv6 on the system:

6) EPEL repository on Centos 7

To install the EPEL repository, issue the following command:

sudo rpm --import http://mirrors.nayatel.com/epel//RPM-GPG-KEY-EPEL-7
sudo rpm -Uvh http://mirrors.nayatel.com/epel/7/x86_64/e/epel-release-7-1.noarch.rpm