Linux Static IP Configuration

Obtaining Networking Info 

Before we move on to editing files, we need to gather some information. Log into the Linode Manager and click the Network tab. In the "Network Configuration"" section you'll find your IP addresses (both public & private), gateways, netmasks and DNS servers.

Keep this information handy, because you'll need to refer to it as you do the configuration. Since Linodes only have one virtual ethernet interface (eth0), you'll need to assign each additional IP to an alias on that interface. This means you'll append a colon and a number to the interface name. For our examples, we're just going to number them in the order they were given, but most outbound connections will originate from the IP assigned to the eth0 interface. If you need server daemons to bind to a particular IP address, you'll need to specify the correct IP in their configuration files.

Please note that although your VPS may have multiple IP addresses assigned to it, you should only specify a default gateway for one IP. This gateway should be the one that corresponds to the IP address you are setting it on. For example, if you are setting the default gateway for "12.34.56.78" you should use "12.34.56.1" for the gateway.

A default gateway should not be specified for private IP addresses. Additionally, the subnet mask for private IP addresses should be set to "255.255.128.0" (not "255.255.255.0").

Important: You must reboot your Linode after adding an IP address to it before the changes will take effect.

DNS Server Settings 

If you've migrated to a new location, you may need to edit your /etc/resolv.conf file so that your Linode can resolve DNS queries. Your nameservers are listed under the "Network" tab. The search and domain lines are optional, but you should definitely include the options rotate line.

In the example below, change the IP addresses to reflect the values shown under the "Network" tab of the Linode Manager.

File: /etc/resolv.conf

domain members.linode.com
search members.linode.com
nameserver 98.76.54.32
nameserver 76.54.32.10
options rotate

Change the nameserver IP addresses to reflect the values shown under the "Network" tab of the Linode Manager.

Debian & Ubuntu 

Since Ubuntu is based on Debian, their configuration is the same. The relevant file to edit is /etc/network/interfaces - the file syntax is fairly straightforward, but you can read the comments in the file for more details about what each line does.

In the example below, change the IP addresses to reflect the values shown under the "Network" tab of the Linode Manager.

File: /etc/network/interfaces

# The loopback interface
auto lo
iface lo inet loopback

# Configuration for eth0 and aliases

# This line ensures that the interface will be brought up during boot.
auto eth0 eth0:0 eth0:1

# eth0 - This is the main IP address that will be used for most outbound connections.
# The address, netmask and gateway are all necessary.
iface eth0 inet static
 address 12.34.56.78
 netmask 255.255.255.0
 gateway 12.34.56.1

# eth0:0
iface eth0:0 inet static
 address 34.56.78.90
 netmask 255.255.255.0

# eth0:1 - Private IPs have no gateway (they are not publicly routable) so all you need to
# specify is the address and netmask.
iface eth0:1 inet static
 address 192.168.133.234
 netmask 255.255.128.0

Restart networking:

/etc/init.d/networking restart

From the Linode, ping each of the default gateways listed on the "Network" tab of the Linode Manager:

ping 12.34.56.1
ping 98.76.54.1

CentOS & Fedora 

Note: CentOS & Fedora may include two services to configure and having the wrong one enabled may cause networking to not come up after making these changes. You can check your configuration using these instructions.

CentOS keeps the information for each interface in a separate file named /etc/sysconfig/network-scripts/ifcfg-<interface_name> so you'll need to create one for eth0 and one for each alias.

In the example below, change the IP addresses to reflect the values shown under the "Network" tab of the Linode Manager.

File: /etc/sysconfig/network-scripts/ifcfg-eth0

# Configuration for eth0
DEVICE=eth0
BOOTPROTO=none

# This line ensures that the interface will be brought up during boot.
ONBOOT=yes

# eth0 - This is the main IP address that will be used for most outbound connections.
# The address, netmask and gateway are all necessary.
IPADDR=12.34.56.78
NETMASK=255.255.255.0
GATEWAY=12.34.56.1

File: /etc/sysconfig/network-scripts/ifcfg-eth0:0

# Configuration for eth0:0
DEVICE=eth0:0
BOOTPROTO=none

# This line ensures that the interface will be brought up during boot.
ONBOOT=yes

# eth0:0
IPADDR=34.56.78.90
NETMASK=255.255.255.0

File: /etc/sysconfig/network-scripts/ifcfg-eth0:1

# Configuration for eth0:1
DEVICE=eth0:1
BOOTPROTO=none

# This line ensures that the interface will be brought up during boot.
ONBOOT=yes

# eth0:1 - Private IPs have no gateway (they are not publicly routable) so all you need to
# specify is the address and netmask.
IPADDR=192.168.133.234
NETMASK=255.255.128.0

Restart networking:

service network restart

From the Linode, ping each of the default gateways listed on the "Network" tab of the Linode Manager:

ping 12.34.56.1
ping 98.76.54.1

Arch Linux 

In the example below, change the IP addresses to reflect the values shown under the Network tab of the Linode Manager. All other details should remain the same. The configuration of networking states occurs in the /etc/rc.conf file. Add a hash sign (e.g. #) to the beginning of the existing INTERFACES and eth0 lines to convert them to comments, then add the following lines to your rc.conf file.

File excerpt: /etc/rc.conf

eth0="eth0 12.34.56.78 netmask 255.255.255.0"
eth0_0="eth0:0 21.43.65.87 netmask 255.255.255.0"
eth0_1="eth0:1 192.168.134.241 netmask 255.255.128.0"

INTERFACES=(eth0 eth0_0 eth0_1)

gateway="default gw 12.34.56.1"
ROUTES=(gateway)

In this example, we configure two static public interfaces on eth0, eth0:0, and eth0:1. Ensure that every interface configuration is included in the INTERFACES list. When you have configured these, issue the following command:

/etc/rc.d/network restart

Due to the way that Arch Linux handles network interfaces, this command will report that the "Stopping the Network Interfaces" operation has failed. When you issue the command ifconfig, you will be able to see the properly configured interfaces.

From the Linode, ping each of the default gateways listed on the "Network" tab of the Linode Manager:

ping 12.34.56.1
ping 98.76.54.1

Gentoo 

In the example below, change the IP addresses to reflect the values shown under the "Network" tab of the Linode Manager. You'll be setting up a static public IP on eth0 and a static private IP on eth0:1. We recommend logging into LISH, since you'll be restarting the network.

First, open /etc/conf.d/net and comment your existing config_ethX and routes_ethX lines:

#config_eth0=( "12.34.56.XXX netmask 255.255.255.0" )
#routes_eth0=( "default gw 12.34.56.1" )
#config_eth1=( "192.168.133.XXX netmask 255.255.128.0" )

Using the comments in /etc/conf.d/net.example as your guide, create a new config_eth0 entry that contains both of your addresses in CIDR notation:

config_eth0=(
        "12.34.56.XXX/24"
        "192.168.133.XXX/17"
)

Tip: Type your netmask here to get correct CIDR.

Now add a new routes_eth0 entry:

routes_eth0=( "default via 12.34.56.1" )

Full example of working /etc/conf.d/net:

config_eth0=(
        "12.34.56.XXX/24"
        "192.168.133.XXX/17"
)

routes_eth0=( "default via 12.34.56.1" )

dns_servers="34.56.78.90 34.56.78.91 34.56.78.92"
dns_search="example.com members.linode.com"
dns_domain="example.com"

Stop your existing eth1 interface and remove it from startup, if applicable:

/etc/init.d/net.eth1 stop
rc-update del net.eth1 default
rm /etc/init.d/net.eth1

Restart networking:

/etc/init.d/net.eth0 restart

From the Linode, ping each of the default gateways listed on the "Network" tab of the Linode Manager:

ping 12.34.56.1
ping 98.76.54.1

OpenSuse 

In the example below, change the IP addresses to reflect the values shown under the "Network"" tab of the Linode Manager.

File: /etc/sysconfig/network/ifcfg-eth0

# Configuration for eth0
BOOTPROTO='static'

# This line ensures that the interface will be brought up during boot.
STARTMODE='onboot'

# eth0 - This is the main IP address that will be used for most outbound connections.
# The address, netmask and gateway are all necessary. The metric is not necessary but
# ensures you always talk to the same gateway if you have multiple public IPs from
# different subnets.
IPADDR='12.34.56.78'
NETMASK='255.255.255.0'

# eth0:0
IPADDR1='34.56.78.90'
NETMASK1='255.255.255.0'
LABEL1='0'

# eth0:1 - Private IP
IPADDR2='192.168.133.234'
NETMASK2='255.255.128.0'
LABEL2='1'

Create the following file if necessary:

File: /etc/sysconfig/network/routes

# Destination   Gateway                 Netmask                 Device
66.246.75.0     0.0.0.0                 255.255.255.0           eth0
0.0.0.0         12.34.56.1                  0.0.0.0                 eth0

Double-check that your /etc/resolv.conf exists and is correct.

Restart networking:

/etc/init.d/network restart

From the Linode, ping each of the default gateways listed on the "Network" tab of the Linode Manager:

ping 12.34.56.1
ping 98.76.54.1

License 

This guide is licensed under a Creative Commons Attribution-No Derivative Works 3.0 United States License. Please feel free to redistribute unmodified copies of it as long as attribution is provided, preferably via a link to this page.