Reverse Tethering won't work for me - is it because my phone isn't rooted?

I've been trying most of the day to reverse tether my phone (Motorola Droid X on Verizon ub the USA), in this case to an Ubuntu VM running on a Windows 7 host via VMWare Workstation. I've followed the instructions in questions like these and everyone seems to quote the exact same blog post , which appears to be the gospel on the topic. Problem is that I can't get it to work. Everything works right up until the command: ./adb shell netcfg usb0 dhcp Which produces the response action 'dhcp' failed (Permission denied) I can't seem to find much of anything on this error message which makes me think: the phone isn't allowing me to do this. Not sure if it's the carrier or the manufacturer or what but I'm basically being told "no" Is it because the phone isn't rooted? My workplace actually has a policy against that so I haven't done it. If not, does anyone have idea what I'm doing wrong?