Proposed F19 Feature: systemd/udev Predictable Network Interface Names

[Kay Sievers]

On Thu, Feb 7, 2013 at 12:07 PM, Bradley Baetz <bbaetz at gmail.com> wrote:
> On 07/02/13 00:33, Michal Schmidt wrote:
>>
>> On 02/05/2013 02:53 AM, Scott Schmit wrote:
>>>
>>>  Is there a program/script we can run that would tell us what the
>>> interface names would be without biosdevname (without running the new
>>> version of systemd on the box)?
>>
>>
>> If you have Fedora 18 with updates applied your systemd is new enough to
>> allow you to see the udev-generated names using:
>>
>> udevadm info --export -p /sys/class/net/$IFACE | grep ID_NET
>>
>> Example output:
>>
>> E: ID_NET_NAME_MAC=enx000f53014229
>> E: ID_NET_NAME_PATH=enp40s0f1d1
>> E: ID_NET_NAME_SLOT=ens4f1d1
>
>
> What happens with USB network devices that are plugged into different slots?
> Currently my iPhone shows up as eth1, but using the above, depending on
> which of two adjacent ports I happen to plug it into, I get:
>
> $ udevadm info --export -p /sys/class/net/eth1 | grep ID_NET
> E: ID_NET_NAME_MAC=enx0226b08178a9
> E: ID_NET_NAME_PATH=enp0s29f7u1c4i2
>
> $ udevadm info --export -p /sys/class/net/eth1 | grep ID_NET
> E: ID_NET_NAME_MAC=enx0226b08178a9
> E: ID_NET_NAME_PATH=enp0s29f7u2c4i2
>
> Will those be treated as two separate devices under this scheme depending on
> which USB port I happen to use?

Yes, the name will change, depending on the port used. But not
randomly like eth1 names, where any other device connected before
could also be be eth1.

> And if so, will that actually matter?

It doesn't with non-legacy tools. Tools that can talk to phones
usually knows how to find the device without relying on a name.

Kay