How to change server IP address from DHCP to static?

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1. Gather the required information

Static IP addresses are assigned for network interfaces. You can find out all your network interfaces names using this command:

ifconfg

You have to pick the one that has the address you already know. For example we have a server with such interfaces:


eth0      Link encap:Ethernet  HWaddr 00:22:15:98:30:27
          inet addr:192.168.0.108  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::222:15ff:fe98:3022/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:491112 errors:0 dropped:0 overruns:0 frame:0
          TX packets:452621 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:553199357 (527.5 MiB)  TX bytes:48077932 (45.8 MiB)
          Interrupt:24 Base address:0x6000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:7039 errors:0 dropped:0 overruns:0 frame:0
          TX packets:7039 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1892466 (1.8 MiB)  TX bytes:1892466 (1.8 MiB)

We see that current IP address is 192.168.0.108, network mask: 255.255.255.0

DNS settings are located in a configuration file /etc/resolv.conf:

bash-4.1$  cat /etc/resolv.conf
# Generated by NetworkManager
nameserver 213.197.128.71
nameserver 213.197.150.130



2. Change IP address to static

Open a configuration file with a desired Linux editor (for example nano, mcedit, vi) which matches your network interface name, in this example we will use eth0:

mcedit /etc/sysconfig/network-scripts/ifcfg-eth0

You will see a configuration file like this:

DEVICE="eth0"
BOOTPROTO="dhcp"
HWADDR="00:22:15:98:30:27"
NM_CONTROLLED="yes"
ONBOOT="yes"

You have to change it to look like this:

Warning!!! You must be sure that the settings below are correct or you will shoot yourself to the leg - you will be disconnected and will not be able to connect again when configuring remotely

DEVICE=eth0
BOOTPROTO=none
ONBOOT=yes
HWADDR=00:22:15:98:30:27  # <-- !!!!leave this setting as is in your current configuration, it will be different than provided you here!!!
NETMASK=255.255.255.0	   # set here your netmask	
IPADDR=192.168.0.22	   # set here your desired STATIC IP ADDRESS		
GATEWAY=192.168.0.1	   # set here your desired Gateway address
TYPE=Ethernet
USERCTL=no
IPV6INIT=no
PEERDNS=yes

Warning!!! You must be sure that the settings above are correct or you will shoot yourself to the leg - you will be disconnected and will not be able to connect again when configuring remotely

Restarting the network

When you are sure that you set up the network correctly - save the changes to an opened file and restart your server networking using this command:

/etc/init.d/network restart



Other settings that have to be changed

When changing the server address you also must make additional changes documented here