Sharing In-Flight WiFi Between iPhone/Pad and Laptop
If you’ve ever purchased WiFi during a flight, you know how amazing it is to be connected to the interweb at 30,000 feet. On many of my flights I hear complaints fill the cabin about people being restricted to using their WiFi on only one device at a time. Many times people are just spoiled, but there is a legitimate need. A great example of this is if you want to move from your iPad to your laptop, you need to login, and then again to switch back to your iPad or iPhone.
How about some background
For any WiFi network to work correctly, your device is identified on the network by it’s MAC address. This address is the physical address supplied by the vendor which is unique to your device only. These MAC addresses are used to assign an IP address, so the network knows what device is supposed to be communicating from what address.
When you connect to the in-flight WiFi, you are assigned an IP Address in an un-provisioned network. For example, this is how you can connect to the UnitedWiFi network and access ONLY the in-flight entertainment. When you purchase the WiFi plan, you are assigned another IP address from a provisioned network. This new network has the ability to communicate across the satellite link across the web.
Ain’t nobody got time for that.
If you don’t want to get stuck with this switching back and forth, here is a quick how-to to get two device online without having to keep logging in (but still only one at a time).
On your phone:
- Connect and pay for the WiFi on your Cell Phone or iPad.
- Go to Settings -> General -> About.
- Locate your WiFi-Address and write it down.
On your laptop:
- Open your computer and disconnect from WiFi.
- Open a terminal prompt (Applications -> Utilities -> Terminal).
- Run: networksetup -listallhardwareports |grep -A2 Wi-Fi
- Locate your WiFi device name, commonly en0 (thats a zero)
- Run: ifconfig <laptop WiFi device> ether <iPhone Wi-Fi Address>
- Connect to the WiFi.
Now the only thing you need to do when you switch devices is turn off the WiFi of the device you DO NOT want to use.
How this works
When you pay for the plan on your iPhone, the MAC address of the iPhone is stored in their system and given an IP Address from their provisioned IP space. When you follow the steps above, your assign your laptop the same MAC address of the iPhone, so they are seen as the same device when your device looks for an IP address on the network.
If you don’t disable WiFi on your unused device, you will see some funky network behavior since both have the same IP address, and WiFi networks are unreliable. To make sure it works, be sure to disable your unused device, but switching is as easy as turning WiFi on and off now.