Make a secure ad hoc wireless control network

At some point along the way (I can’t remember when…), Apple removed authentication security from the ad hoc network function “Create a network…” in the Wi-Fi setup. I use ad hoc networks to link up mobile devices to Macs running Max, QLab, Isadora, etc, and not being able to lock up the network is a real drag, and security hole. Here’s a better method.

Setup

First, go to System Preferences>Sharing. Uncheck “Internet Sharing’ if it is checked. Then, enter the following in Terminal:

sudo networksetup -createnetworkservice Loopback lo0
sudo networksetup -setmanual 172.20.42.42 255.255.255.255

You can alter the IP address to your liking. You will use it in a few more steps.

Configuration

  1. Go to System Preferences>Network and configure the newly created ‘Loopback’ network device to match the IP and subnet above, setting the ‘Configure IPv4’ menu to ‘Manually.”
  2. After setting up ‘Loopback,’ go to System Preferences>Sharing. Change ‘Share your connection from’ to ‘Loopback’
  3. Under ‘To computers using’ check ‘Wi-Fi’
  4. Click ‘Wi-Fi options…’ and set a name, password and channel for the new wireless network.
  5. Check the ‘Internet Sharing’ box to enable the new secure network.