Introduction

1 The necessity for IP replacement

2 How to add new IP in Windows or Linux system

• In Windows system,  we will demonstrate adding new IP as primary with powershell script.
• In Linux system,  we will demonstrate editing device file to add new IP address.

2.1 Add new IP in Windows System

•     Start "Windows Powershell ISE"

            Enter ise in the Search box. And click Windows PowerShell ISE to open it.

 

• Copy and Edit PowerShell script 

Please copy the following script and edit the $OldIPaddress,$NewIPaddress,$NewSubnetMask,$NewGateway value. The value information can be found in our notification email.  

===========Copy start=============

function Convert-IpAddressToMaskLength([string] $dottedIpAddressString)

{
  $result = 0;
  [IPAddress] $ip = $dottedIpAddressString;
  $octets = $ip.IPAddressToString.Split('.');
  foreach($octet in $octets)
  {
    while(0 -ne $octet)
    {
      $octet = ($octet -shl 1) -band [byte]::MaxValue
      $result++;
    }
  }
  return $result;
}
$OldIPaddress = "xx.xx.xx.xx"
$NewIPaddress="xx.xx.xx.xx"
$NewSubnetMask = "255.255.255.xx"
$NewGateway="xx.xx.xx.xx"
$interfaceName= Get-NetIPAddress | Where-Object { $_.IPAddress -eq $OldIPaddress } | Get-NetAdapter | Select-Object -ExpandProperty Name
New-NetIPAddress -InterfaceAlias $InterfaceName -IPAddress $NewIPAddress -PrefixLength (Convert-IpAddressToMaskLength $NewSubnetMask) -DefaultGateway $NewGateway
Set-NetIPAddress –IPAddress $OldIPaddress –SkipAsSource $True

==========  Copy  end ===================

• Execute the PowerShell script

Please click on the green button in the red box to run the PowerShell script

 

2.2 Add new IP in the Linux system

• Prefix Number 24 = netmask 255.255.255.0
• Prefix Number 25 = netmask 255.255.255.128
• Prefix Number 26 = netmask 255.255.255.192

2.2.1 CentOS

• Get the network device name via the command "ifconfig"

            Use the name of the network card in the red box to the name of the network card obtained in the above step. 

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

        

•  Update the configuration file

IPADDR=<Old IP>

PREFIX=<Old Prefix>

GATEWAY=<Old Gatway>

IPADDR=<New IP>
PREFIX=<New Prefix>
GATEWAY=<New Gatway>
IPADDR1=<Old IP>
PREFIX1=<Old Prefix>
GATEWAY1=<Old Gatway>

 

• Save the configuration file and restart the network service

    systemctl restart network

    

   2.2.2 Ubuntu20/18

• Switch to root

Execute the  command "sudo -i" to switch to root user

sudo -i

• Get correct configuration file name

        Find the network configuration file under /etc/netplan.   Please note that your network configuration file name may not be 01-netcfg. yaml

        

 

• Modifying Network Configuration File /etc/netplan/01-netcfg.yaml 

        

    Vi /etc/netplan/01-netcfg.yaml    

 

• Replace the New IP, New prefix, New Gateway in the following lines 

network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      addresses:
        - Old IP/Old prefix
        - New IP/New prefix
      nameservers:
        addresses:
          - "8.8.8.8"
      routes:
        - to: 0.0.0.0/0
          via: New gateway

Here is a sample to add new IP

Before

After Modified

• Make the configuration effective

netplan apply
ip a

2.2.3 Debian/Ubuntu14/Ubuntu16

modify file 

/etc/network/interfaces

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0

auto eth0
iface eth0 inet static
        address 108.181.192.108
        netmask 255.255.255.0
        gateway 108.181.192.1
iface eth0:0 inet static
        address 172.107.178.108
        netmask 255.255.255.0

Please note that eth0 fills in the new IP information. If you don’t want the netmask field, you can also fill in 108.181.192.108/24. Please replace 108.181.192.108 with your own new IP.

eth0:0 is used to retain the old IP information. In order to avoid conflicts, there is no need to fill in the gateway field here

 

Then restart the network through the systemctl restart networking command.

systemctl restart networking

detection command

ifconfig
ip a

If all goes well, you will see something similar to the image below, with eth0 and eth0:0 network cards appearing. And the result of ip a shows that there will be two ips under eth0.

 

If it is the same as the picture above, it means that the ip has been added successfully. Or you can connect to your server with both the new IP and the old IP, then you can end this reading 

 

If the second ip does not appear, or RTNETLINK answers: File exists error. then go to the next step

If the network card and IP do not appear, you can use the following command to restore the default configuration of eth0:0.

But this will cause the current session to be disconnected, and then please connect through IPMI or other consoles

ip addr flush dev eth0

Then restart the network

systemctl restart networking
ifup eth0
ifup eth0:0

 

3 Test the new IP

• You can connect to your server using the new IP address via RDP/SSH. If you are able to establish a connection and perform remote operations successfully, it means the new IP is functioning properly.
• After updating the IP address, you may need to restart certain services on your server, such as web services like Apache/Nginx, email services, DNS services, etc. This is necessary to ensure that the services start using the updated IP address.

4 Remove the old IP from the server

4.1 Remove old IP from the Windows system

Remove-NetIPAddress  -IPAddress "Old IP "  -DefaultGateway "old gateway"  -Confirm:$false

4.2 For Linux：