If you have an internet connection on your Mac computer, you can share the same connection with other devices using ad-hoc Wi-Fi internet sharing. The step-by-step illustrated instructions shared below will allow your Mac computer to act as an Wi-Fi router, Wi-Fi internet sharing capability comes built-in with Mac OS X and no additional software needs to be installed – the internet sharing feature just needs to get activated as shown ahead.
Steps to Activate internet sharing via AirPort (Mac Wi-Fi) to other devices:-
Open your Mac System Preference and click the “Sharing” button from “Internet and Wireless” section.
Now click the “Internet Sharing” check-box and make sure you select options as per you configuration, for example in the screen-shot shared below we are allowing the Ethernet connection to get shared via AirPort/WiFi and iPhone USB.
Once allowed and configured the on-screen “Internet Sharing: On” status light will turn green, and your mac will be visible to all in-range WiFi devices with internet sharing enabled.
Enjoy, your Mac as a wireless internet router.