Lion won't give out DHCP addresses with Internet Sharing

Question

Lion doesn't seem to be giving out DHCP addresses when I turn on Internet Sharing. My firewall is off, I create a shared network with no security sharing ethernet->wifi. In Network Preferences the Wifi connection shows as yellow, with a self-assigned IP, and any device I try to connect (e.g., iPad) doesn't get an address. Help!

Answer 1

I finally figured it out.

• You said your Firewall is off. You should double-check. This will definitely cause Internet Sharing to not work. System Preferences -> Security & Privacy -> Firewall.
• In the "Sharing" panel, change your Computer Name to something simple. Instead of "Elliot's MacBook Pro", use "MBP".
  • Turn off Internet Sharing (if it's on). Make sure you have set "Share your connection from:" to "Ethernet", and "To computers using:" to "Wi-Fi". Change the "Wi-Fi Options..." and save.
• If that didn't work: Turn off Wi-Fi on your Lion Mac. Make sure you have internet access from Ethernet, and that it works (test a site in a browser).
• For your Wi-Fi connection, set "Configure IPv4" to "Using DHCP". In the "DNS" tab, delete any existing entries.

Hope this helps!

Answer 2

I'm using it. InternetSharing and Firewall: on do work together. (It's already huge enough a security shame to have to start a wireless network with WEP). Beware: you should not ride the raw Internet with your Firewall: off.

On the other hand I'm also sure of another behaviour. InternetSharing doesn't start bootpd if the network connexion to Ethernet isn't up, i.e. doesn't have an IP valid address. (And bootpd is the daemon which distribute IP addresses on the Wi-fi side).

Within the valid network configuration on top of which you want to build a sharing of your Ethernet connexion,

• the Ethernet connexion should be marked as green, with a valid IP Address,
• the Wi-Fi connexion should be marked as yellow, with Network Name: No network selected.

When you start Internet Sharing 2 details will change:

• the Wi-Fi icon in the menu bar should switch to grey with a white arrow,
• the Wi-Fi connexion should be marked as green, with Network Name: Internet Sharing: on.

Answer 3

This thread along with https://discussions.apple.com/thread/2108373 helped me.

I turned off all internet connection sharing.

I deleted the following files:

/Library/Preferences/SystemConfiguration/com.apple.nat.plist /Library/Preferences/SystemConfiguration/NetworkInterfaces.plist /Library/Preferences/SystemConfiguration/com.apple.airport.preferences.plist

restarted

Turned on internet connection sharing

This resulted in Internet Connection sharing giving the client the correct DHCP lease details.