Proposed F19 Feature: systemd/udev Predictable Network Interface Names

Jaroslav Reznik jreznik at
Wed Jan 23 19:59:07 UTC 2013

= Features/SystemdPredictableNetworkInterfaceNames =

Feature owner(s):  Kay Sievers <kay at redhat dot com>
The udevd service has a long history of providing predicatable names for block 
devices and others. For Fedora 19 we'd like to provide the same for network 
interfaces, following a similar naming scheme, but only as fallback if not 
other solution such as biosdevname is installed or the administrator manually 
defined network interface names via udev rules or the old network scripts.

== Detailed description ==
The classic naming scheme for network interfaces applied by the kernel is to 
simply assign names beginning with "eth0", "eth1", ... to all interfaces as 
they are probed by the drivers. As the driver probing is generally not 
predictable for modern technology this means that as soon as multiple network 
interfaces are available the assignment of the names "eth0", "eth1" and so on 
is generally not fixed anymore and it might very well happen that "eth0" on one 
boot ends up being "eth1" on the next. This can have serious security 
implications, for example in firewall rules which are coded for certain naming 
schemes, and which are hence very sensitive to unpredictable changing names.

Starting with v197 systemd/udev can automatically assign predictable, stable 
network interface names for all local Ethernet, WLAN and WWAN interfaces. This 
is a departure from the traditional interface naming scheme ("eth0", "eth1", 
"wlan0", ...), but should fix real problems.

This feature is about enabling this as default in Fedora, but only as a 
fallback if the user/administrator did not manually assign names to interfaces 
via udev rules, or via the old networking scripts, or if biosdevname is 

For a longer discussion about this feature see the upstream documentation. 

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