How to use a Generic USB 2.0 10/100M Ethernet Adaptor RD9700 on Mac OS 10.10 Yosemite
by Steven Skoczen — about a 2 minute read.
If you bought a cheap aftermarket USB-Ethernet adapter like me and found that it doesn't work on Yosemite, here's what you need to get it going.


Seriously. You can stop tearing you hair out now. It'll all be ok.


As with all advice on the internet, you can't sue me if this sets fire to your cat or sends ninjas to your house. You're doing this on your own, and I assume no liability or warranty for what you do.


Steps to get your adapter working


1. Uninstall the dozens of other drivers you may have installed in the process of trying to get this working.

2. Unplug your USB adapter, and reboot and give yourself a clean slate.

3. Download and install the drivers from the CD, kindly uploaded by this fine human being.

4. Reboot.

5. Open your terminal, and run sudo nvram boot-args="kext-dev-mode=1"

6. Reboot.

7. Open your terminal, and run sudo kextload /System/Library/Extensions/USBCDCEthernet.kext

8. Reboot.

9. Plug in your USB Adapter, with a live ethernet cable.

10. Open System Preferences, and go to the Network Pane.

11. Hit the + button in the bottom right, select the "USB 2.0 10/100M Ethernet Adapter", and hit add.

You're all set! Your adapter works!

Apologize to the people you care about for the things you've said over the past few hours. They won't understand, but they will forgive you.


What's going on.

The old drivers still work, no problem, but are being blocked in Yosemite because they aren't "signed" properly, since they weren't re-issued for Yosemite. As "unsigned" drivers, Mac OS refuses to load them, saying they constitute a security hazard.


What step 5 does is instructs your computer to set itself to "developer mode", which allows you to load unsigned kexts. This is a mild security risk, but it should be fine for most people. If you're in doubt, please make the decision that makes the most sense for your security concerns. You might be better off just buying legit Apple hardware so you don't have to disable the security. That's your call.


If you ever do go legit and want to undo it, just run sudo nvram boot-args="kext-dev-mode=0, and things will be back where you left them.


Anyhow, after hours of searching and pulling out my own hair, I thought it'd be worth sharing the solution! Enjoy!