How to Configure Static IP Address on CentOS 6.3 Linux Server

This post will covers the steps to configure static ip address, default gateway, netmask, dns server and make a network auto start at boot on linux CentOS 6.3. Server normally configured with static ip address, so that easier to maintain the configuration on it’s client and DNS server will always able to resolve it.

DEVICE="eth0"
BOOTPROTO="dhcp"
HWADDR="xx:xx:xx:xx:xx:xx"
NM_CONTROLLED="yes"
ONBOOT="no"
TYPE="Ethernet"
UUID="xxxxxxxx-05a0-4adf-84fd-850aca6521c7"

1. Configure eth0:

[root@centos63 ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE="eth0"
BOOTPROTO="static"
HWADDR="xx:xx:xx:xx:xx:xx"
NM_CONTROLLED="yes"
ONBOOT="yes"
TYPE="Ethernet"
UUID="xxxxxxxx-05a0-4adf-84fd-850aca6521c7"
IPADDR=192.168.1.54
NETMASK=255.255.255.0

2. Configure Default gateway:

[root@centos63 ~]# vi /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=centos63.ehowstuff.local
GATEWAY=192.168.1.1

3. Restart Network interface:

[root@centos63 ~]# service network restart
Shutting down interface eth0:                              [  OK  ]
Shutting down loopback interface:                          [  OK  ]
Bringing up loopback interface:                            [  OK  ]
Bringing up interface eth0:                                [  OK  ]

4. Configure DNS server :

[root@centos63 ~]# vi /etc/resolv.conf
nameserver 8.8.8.8

How to Check and Disable SELinux on CentOS 6.3

Security-Enhanced Linux (SELinux) is a Linux feature that provides security mechanism for supporting access control security policies implemented in the kernel. SELinux checking for allowed operations after standard Linux discretionary access controls are checked. In this post i will shows on how to check SELinux status and disables SELinux on linux CentOS 6.3.

1. How to check SELinux on CentOS 6.3 ?

[root@centos63 ~]# sestatus
SELinux status:                 enabled
SELinuxfs mount:                /selinux
Current mode:                   enforcing
Mode from config file:          enforcing
Policy version:                 24
Policy from config file:        targeted

or

[root@centos63 ~]# getenforce
Enforcing

2. How to disable SELinux on CentOS 6.3 permanently ?

[root@centos63 ~]# cat /etc/selinux/config

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#     enforcing - SELinux security policy is enforced.
#     permissive - SELinux prints warnings instead of enforcing.
#     disabled - No SELinux policy is loaded.
SELINUX=enforcing
# SELINUXTYPE= can take one of these two values:
#     targeted - Targeted processes are protected,
#     mls - Multi Level Security protection.
SELINUXTYPE=targeted


or

[root@centos63 ~]# cat /etc/sysconfig/selinux

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#     enforcing - SELinux security policy is enforced.
#     permissive - SELinux prints warnings instead of enforcing.
#     disabled - No SELinux policy is loaded.
SELINUX=enforcing
# SELINUXTYPE= can take one of these two values:
#     targeted - Targeted processes are protected,
#     mls - Multi Level Security protection.
SELINUXTYPE=targeted


Change “SELINUX=enforcing” to “SELINUX=disabled” :


# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#     enforcing - SELinux security policy is enforced.
#     permissive - SELinux prints warnings instead of enforcing.
#     disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of these two values:
#     targeted - Targeted processes are protected,
#     mls - Multi Level Security protection.
SELINUXTYPE=targeted


Note : This will disable SELinux on your next reboot

[root@centos63 ~]# sestatus
SELinux status:                 disabled

3. How to disable SELinux on CentOS 6.3 immediately without reboot :

[root@centos63 ~]# setenforce 0

Check SELinux status :

[root@centos63 ~]# getenforce
Permissive