7.2.5. Alias and Clone Files
Two lesser-used types of interface configuration files are alias and clone files. As the ip
command of the iproute package now supports assigning multiple address to the same interface it is no longer necessary to use this method of binding multiple addresses to the same interface.
At the time of writing, NetworkManager does not detect IP aliases in ifcfg
files. For example, if ifcfg-eth0
and ifcfg-eth0:1
files are present, NetworkManager creates two connections, which will cause confusion.
For new installations, users should select the
Manual method on the IPv4 or IPv6 tab in
NetworkManager to assign multiple IP address to the same interface. For more information on using this tool, refer to
Chapter 6, NetworkManager.
Alias interface configuration files, which are used to bind multiple addresses to a single interface, use the ifcfg-if-name
:alias-value
naming scheme.
For example, an ifcfg-eth0:0
file could be configured to specify DEVICE=eth0:0
and a static IP address of 10.0.0.2
, serving as an alias of an Ethernet interface already configured to receive its IP information via DHCP in ifcfg-eth0
. Under this configuration, eth0
is bound to a dynamic IP address, but the same physical network card can receive requests via the fixed, 10.0.0.2
IP address.
Alias interfaces do not support DHCP.
A clone interface configuration file should use the following naming convention: ifcfg-if-name
-clone-name
. While an alias file allows multiple addresses for an existing interface, a clone file is used to specify additional options for an interface. For example, a standard DHCP Ethernet interface called eth0
, may look similar to this:
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp
Since the default value for the USERCTL
directive is no
if it is not specified, users cannot bring this interface up and down. To give users the ability to control the interface, create a clone by copying ifcfg-eth0
to ifcfg-eth0-user
and add the following line to ifcfg-eth0-user
:
USERCTL=yes
This way a user can bring up the eth0
interface using the /sbin/ifup eth0-user
command because the configuration options from ifcfg-eth0
and ifcfg-eth0-user
are combined. While this is a very basic example, this method can be used with a variety of options and interfaces.
It is no longer possible to create alias and clone interface configuration files using a graphical tool. However, as explained at the beginning of this section, it is no longer necessary to use this method as it is now possible to directly assign multiple IP address to the same interface. For new installations, users should select the
Manual method on the IPv4 or IPv6 tab in
NetworkManager to assign multiple IP address to the same interface. For more information on using this tool, refer to
Chapter 6, NetworkManager.