In a previous post I showed you how to install the Ralink RT5370 and equivalent USB WiFi adapter for OSX Yosemite 10.10.x. In this brief post we will use the information learned in that previous post and adapt it to install the same driver on the new OSX version released a few weeks ago, El Capitan 10.11.x.
Note that throughout the article I will make reference to the following tools and drivers that you can download from here:
1. Bear Extender (GUI for managing the WLAN)
2. RT2870USBWirelessDriver.ext (The Ralink Driver)
3. SIPUtility (an application to manage El Capitan SIP)
But before we start you should understand that Apple made a number of security changes to El Capitan, one of them called SIP (System Integrity Protection). Follow the link for more details about SIP, but the most relevant to us is to understand that in a nutshell the driver will not work (load into the kernel) out of the box, and we need to disable SIP completely for it to work.
As such you need to first run the SIP Utility (credits go to the hacker cvad) to disable SIP completely:
Reboot your machine, and then copy the RT2870USBWirelessDriver.ext driver to /System/Library/Extensions:
Final step is to install the Bear Extender WiFi management GUI. Once you reboot the machine once more, you are able to use the Ralink driver on El Capitan!
1. Download Pacifist from https://www.charlessoft.com/cgi-bin/pacifist_download.cgi?type=dmg
2. Open the installer.pkg file from the driver you downloaded in pacifist, and select to install to default location, and use administrator privilege
4. Install Bear Extender WiFi management GUI. Once you reboot the machine once more, you are able to use the Ralink driver on El Capitan!
EDIT (10/11/2015): If you are having issues to disable SIP with SIPUtility, you may try the KCPM Utility Pro.