Proposed F19 Feature: systemd/udev Predictable Network Interface Names

[Dan Williams]

On Tue, 2013-01-29 at 18:38 +0000, Matthew Garrett wrote:
> On Tue, Jan 29, 2013 at 12:32:30PM -0600, Dan Williams wrote:
> 
> > Except then you run into phones or WWAN cards that show up as Ethernet
> > devices, but aren't really Ethernet but just IP-in-8023-frames because
> > that was easier to do on Windows.  That one is quite fun, and there's no
> > good way to catch them all.  We're obviously behind by marking them
> > FLAG_WWAN in the kernel, which has to be done by device IDs, becasue
> > some devices use standard cdc-ether or cdc-eem and you can't reliably
> > tell them apart from some random D-Link DUB100.
> 
> Sure, but that's a fundamentally unsolvable problem - if my primary 
> network connection is via a USB device there's a reasonable chance that 
> it'll be called usb0 anyway. The name isn't providing extra information 
> here.

Actually usbnet uses this logic:

usb%d = default
eth%d = FLAG_ETHER && !FLAG_POINTTOPOINT && !(dev_addr[0] & 0x02)
wlan%d = FLAG_WLAN
wwan%d = FLAG_WWAN

so it's really a crapshoot depending on kernel version and which devices
have been flagged explicitly.  Some classes of device will get usb0 and
some with get eth0 and there's no really clear line about which ones are
actually really ethernet and which are pseduo-ethernet.

Also, 'ipeth' (iPhone USB ethernet tethering) uses "eth%d".  Go figure.

Dan