IP aliasing is a special network configuration for your dedicated servers you to associate multiple IP addresses with a single network interface.
The following sections contain the configurations for the most commonly used distributions/operating systems.
Concerning current distributions, please note that the proper procedure to configure your network interface may be subject to change. We recommend to consult the manuals and knowledge resources of the respective OS versions if you experience any issues
Debian 6/7/8 and derivatives
Step 1 Create a backup
First, make a copy of the config file, so that you can revert at any time:
# cp /etc/network/interfaces /etc/network/interfaces.bak
Step 2 Edit the config file
Note that the names of the network interfaces in our examples may differ from your own. Please adjust to your appropriate interface names.
You can now modify the config file:
# nano /etc/network/interfaces
You then need to add a secondary interface:
auto eth0:0
iface eth0:0 inet static
address ADDITIONAL_IP
netmask 255.255.255.255
To ensure that the secondary interface is enabled or disabled whenever the eth0 interface is enabled or disabled, you need to add the following line to the eth0 configuration:
# post-up /sbin/ifconfig eth0:0 ADDITIONAL_IP netmask 255.255.255.255 broadcast ADDITIONAL_IP
# pre-down /sbin/ifconfig eth0:0 down
If you have two additional IPs to configure, the /etc/network/interfaces file should look like this:
auto eth0
iface eth0 inet static
address SERVER_IP
netmask 255.255.255.0
broadcast xxx.xxx.xxx.255
gateway xxx.xxx.xxx.254
auto eth0:0
iface eth0:0 inet static
address ADDITIONAL_IP 1
netmask 255.255.255.255
auto eth0:1
iface eth0:1 inet static
address ADDITIONAL_IP 2
netmask 255.255.255.255
Or like this:
auto eth0
iface eth0 inet static
address SERVER_IP
netmask 255.255.255.0
broadcast xxx.xxx.xxx.255
gateway xxx.xxx.xxx.254
# ADDITIONAL_IP 1
post-up /sbin/ifconfig eth0:0 FAILOVER_IP1 netmask 255.255.255.255 broadcast ADDITIONAL_IP 1
pre-down /sbin/ifconfig eth0:0 down
# ADDITIONAL_IP 2
post-up /sbin/ifconfig eth0:1 FAILOVER_IP2 netmask 255.255.255.255 broadcast ADDITIONAL_IP 2
pre-down /sbin/ifconfig eth0:1 down
Step 3 Restart the interface
You now need to restart your interface:
# /etc/init.d/networking restart
Debian 9+, Ubuntu 17.04, Fedora 26+ and Arch Linux
On these distributions, the naming of interfaces as eth0, eth1 (and so on) is abolished. We will therefore use systemd-network more generally.
Step 1 Create a backup
First, make a copy of the config file, so that you can revert at any time:
# cp /etc/systemd/network/50-default.network /etc/systemd/network/50-default.network.bak
Step 2 Edit the config file
You can now add your additional IP to the config file, as follows:
# nano /etc/systemd/network/50-default.network
[Address]
Address=ADDITIONAL_IP/32
Label=ADDITIONAL_IP # optional
The label is optional. It’s just for distinguishing between your various additional IPs.
Step 3 Restart the interface
You now need to restart your interface:
# systemctl restart systemd-networkd
Ubuntu 17.10 and following
Each additional IP address will need its own line in the configuration file. The configuration file is called “50-cloud-init.yaml” and is located in /etc/netplan.
Step 1 Determine the interface
# ifconfig
Note the interface name and its MAC address.
Step 2 Create the configuration file
Connect to your server via SSH and run the following command:
# nano /etc/netplan/50-cloud-init.yaml
Next, edit the file with the content below, replacing INTERFACE_NAME MAC_ADDRESS and ADDITIONAL_IP:
network:
version: 2
ethernets:
INTERFACE_NAME:
dhcp4: true
match:
macaddress: MAC_ADDRESS
set-name: INTERFACE_NAME
addresses:
- ADDITIONAL_IP/32
Save and close the file. You can test the configuration with the following command:
# netplan try
Step 3 Apply the change
Next, run the following commands to apply the configuration:
# netplan apply
CentOS and Fedora (25 and earlier)
Step 1 Create the config file
First, make a copy of the source file so that you can use it as a template:
# cp /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth0:0
Step 2 Edit the config file
You can now modify the eth0:0 file in order to replace the IP:
# nano /etc/sysconfig/network-scripts/ifcfg-eth0:0
First, replace the name of the device, then replace the existing IP with the additional IP you have received:
DEVICE="eth0:0"
ONBOOT="yes"
BOOTPROTO="none" # For CentOS use "static"
IPADDR="ADDITIONAL_IP"
NETMASK="255.255.255.255"
BROADCAST="ADDITIONAL_IP"
Step 3 Start the alias interface
You now need to start your alias interface:
# ifup eth0:0
Gentoo
Step 1 Create a backup
First, make a copy of the config file, so that you can revert at any time:
# cp /etc/conf.d/net /etc/conf.d/net.bak
Step 2 Edit the config file
Now you have to edit the file to add the additional IP. In Gentoo, an alias is added directly in the eth0 interface. You do not need to create an eth0:0 interface like in other distributions.
The server’s default IP and config_eth0= should stay on the same line.
All you need to do is add a line break after the netmask 255.255.255.0 and add your additional IP (SERVER_IP must be replaced by your server’s primary IP).
# nano /etc/conf.d/net
You therefore need to add the following:
config_eth0=( "SERVER_IP netmask 255.255.255.0" "ADDITIONAL_IP netmask 255.255.255.255 brd ADDITIONAL_IP" )
The /etc/conf.d/ net file must contain the following:
#This blank configuration will automatically use DHCP for any net.
# scripts in /etc/init.d. To create a more complete configuration,
# please review /etc/conf.d/net.example and save your configuration
# in /etc/conf.d/net (this file :]!).
config_eth0=( "SERVER_IP netmask 255.255.255.0"
"ADDITIONAL_IP netmask 255.255.255.255 brd ADDITIONAL_IP" )
routes_eth0=( "default gw SERVER_IP.254" )
In order to ping your additional IP, simply restart the network interface.
Step 3 Restart the interface
You now need to restart your interface:
# /etc/init.d/net.eth0 restart
openSUSE
Step 1 Create a backup
First, make a copy of the config file, so that you can revert at any time:
# cp /etc/sysconfig/network/ifcfg-ens32 /etc/sysconfig/network/ifcfg-ens32.bak
Step 2 Edit the config file
Open the file:
# nano /etc/sysconfig/network/ifcfg-ens32
Then add the following:
IPADDR_1=ADDITIONAL_IP
NETMASK_1=255.255.255.255
LABEL_1=ens32:0
Finally, reboot your server to apply the changes.
cPanel (on CentOS 6)
Step 1 Create a backup
First, make a copy of the config file, so that you can revert at any time:
# cp /etc/ips /etc/ips.bak
Step 2 Edit the config file
You then need to edit the /etc/ips file:
# nano editor /etc/ips
Then add the additional IP to the file:
ADDITIONAL_IP:255.255.255.255:ADDITIONAL_IP
Next, add the IP in /etc/ipaddrpool:
ADDITIONAL_IP
Step 3 Restart the interface
You now need to restart your interface:
# /etc/init.d/ipaliases restart
Windows Servers
Windows servers are often DHCP-enabled in the network configuration. If you have already set up a additional IP or switched your configuration to a fixed IP, go directly to the next step.
Otherwise, you need to first switch from a network-level DHCP configuration to a fixed IP configuration.
Open the command prompt cmd or powershell, then type the following command:
ipconfig /all
This will return a result similar to the following example:
Identify and write down your IPv4, subnet mask, default gateway and the name of the network interface controller (network adapter).
In our example, the server IP is 94.23.229.151.
You can perform the next steps via either a command-line interface or the graphical user interface.
Via a command-line interface (recommended)
In the commands below, you need to replace:
| Command | Value |
| NETWORK_ADAPTER | Name of the network adapter (in our example: Local Area Connection) |
| IP_ADDRESS | Server IP address (in our example: 94.23.229.151) |
| SUBNET_MASK | Subnet mask (in our example: 255.255.255.0) |
| GATEWAY | Default gateway (in our example: 94.23.229.254) |
| ADDITIONAL_IP | Address IP you want to add |
Be careful – the server will no longer be accessible if you enter incorrect information. You will then have to make the corrections in Winrescue mode or via the KVM.
In the command prompt
Switch to a fixed IP:
netsh interface ipv4 set address name="NETWORK_ADAPTER" static IP_ADDRESS SUBNET_MASK GATEWAY
Set the DNS server:
netsh interface ipv4 set dns name="NETWORK_ADAPTER" static 213.186.33.99
Add additional IP:
netsh interface ipv4 add address "NETWORK_ADAPTER" ADDITIONAL_IP 255.255.255.255
Your additional IP is now functional.
Via the graphical user interface
- Go to Start > Control Panel > Network and Internet > Network and Sharing Centre > Change Adapter Settings(in the left-hand menu).
- Right-click on Local Area Connection.
- Click on Properties.
- Select Internet Protocol Version 4 (TCP/IPv4), then click on Properties.
- Click on Use the following IP address and type in your server’s primary IP, subnet mask and default gateway information obtained by using the ipconfig command above. In the “Preferred DNS Server” box, type 213.186.33.99.
Be careful – the server will no longer be accessible if you enter incorrect information. You will then have to make the corrections in Winrescue mode or via the KVM.
Then click on Advanced (still in the TCP/IP Settings).
In the IP Address section, click Add:
Type in your additional IP and the subnet mask 255.255.255.255:
Click on Add.
Your additional IP is now functional.
FreeBSD
Step 1 Determine the interface
Determine the name of your primary network interface. You can use the ifconfig command for this operation:
# ifconfig
This will return the following:
ifconfig
>>> nfe0: flags=8843 metric 0 mtu 1500
>>> options=10b
>>> ether 00:24:8c:d7:ba:11
>>> inet 94.23.196.18 netmask 0xffffff00 broadcast 94.23.196.255
>>> inet 87.98.129.74 netmask 0xffffffff broadcast 87.98.129.74
>>> media: Ethernet autoselect (100baseTX )
>>> status: active
>>> lo0: flags=8049 metric 0 mtu 16384
>>> options=3
>>> inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
>>> inet6 ::1 prefixlen 128
>>> inet 127.0.0.1 netmask 0xff000000 v comsdvt#
In our example, the name of the interface is therefore nfe0.
Step 2 Create a backup
Next, make a copy of the config file, so that you can revert at any time:
# cp /etc/rc.conf /etc/rc.conf.bak
Step 3 Edit the config file
Edit the /etc/rc.conf file:
# nano /etc/rc.conf
Then add this line at the end of the file: ifconfig_INTERFACE_alias0=”inet ADDITIONAL_IP netmask 255.255.255.255 broadcast ADDITIONAL_IP”.
Replace INTERFACE and ADDITIONAL_IP with the name of your interface (identified in the first step) and your additional IP, respectively. Here is an example:
# ifconfig_nfe0_alias0="inet 87.98.129.74 netmask 255.255.255.255 broadcast 87.98.129.74"
Step 4 Restart the interface
You now need to restart your interface:
# /etc/rc.d/netif restart && /etc/rc.d/routing restart
Solaris
Step 1 Determine the interface
Determine the name of your primary network interface. You can use the ifconfig command for this operation:
# ifconfig -a
This will return the following:
ifconfig -a
lo0: flags=2001000849 mtu 8232 index 1
inet 127.0.0.1 netmask ff000000
e1000g0: flags=1000843 mtu 1500 index 2
inet 94.23.41.167 netmask ffffff00 broadcast 94.23.41.255
ether 0:1c:c0:f2:be:42
In our example, the name of the interface is therefore e1000g0.
Step 2 Create the config file
# nano /etc/hostname.e1000g0:1
In this file, enter the following: ADDITIONAL_IP/32 up, where ADDITIONAL_IP is your additional IP. For example:
188.165.171.40/32 up
Step 3 Restart the interface
You now need to restart your interface:
# svcadm restart svc:/network/physical:default
Troubleshooting
If you are unable to establish a connection from the public network to your alias IP and suspect a network problem, please reboot the server in Rescue Mode and setup the alias directly on the server.
In order to do that, once you’ve rebooted your server in Rescue Mode, please do the following command:
# ifconfig eth0:0 ADDITIONAL_IP netmask 255.255.255.255 broadcast ADDITIONAL_IP up
Where you will replace ADDITIONAL_IP by the actual additional IP.
Next, simply ping your additional IP from the outside. If it works, it probably means that there is a configuration error that requires to be fixed. If, on the contrary, the IP is still not working, please inform our support team by creating a support request in your Client Area