Fedora Core 5 and SB5120
I am having the same problem. The ethernet port on my SB5120 died during an eletrical storm, and the USB connection will not work.
What I have done so far:
1. Load usbnet using 'modprobe usbnet' , loads but I cannot alias it to eth2 and use it as an interface using my /usr/bin/system-config-network tool.
2. Edit /etc/modprobe.conf , adding the lines:
alias usbnet eth2
options usbnet irq=14
When I plug in the modem, it says ( paraphrased ) "0 out of 1 options chosen" ,and still does not work as a device.
3. type 'modprobe CDCEther', system give a critical error that basically says the module cannot be found.
Right now, I have a Windows laptop with Internet Connection Sharing turned on that is providing Internet connectivity, but I would like to get rid of this bulky setup as quickly as possible. Comcast can come out and replace my modem next week, but it would be nice to fix it sooner by making the USB port on the cable modem work with Linux.
Any ideas? I have not found any solution for this via Google.com searches.
One note is the the device is seen when I plug it in, evidenced by entries in DMESG output. But apparently it is not configured as a device.