Using the Raspberry Pi to Turn an iPad into a Real Computer, part 4: RaspAP

My previous post was about pre-configuring the Pi for headless booting that automatically connects to your wireless network.

This is fine for your home network, but it will be difficult to get connected to the Pi when you are traveling. Also, if you are planning to leave the Pi at home, and never use it while traveling, that is waste of a Raspberry Pi. There is a global shortage of Pi’s; they are pretty much impossible to get, even at Pandemic-Profiteering prices. If you just want to do occasional Unix shit on an iPad when you are at home, just use a VM. If you do want to use the Pi out in the field, I recommend RaspAP.

If the headless install went well, you should be able to log into the Pi via SSH and run the RaspAP installer script. I learned about RaspAP from this video:

All did not go well for me in the beginning. I couldn’t connect to the Pi wirelessly to save my life. If I plugged it in to a switch, connecting was not a problem. I tried and tried dozens of different things. I even tried a completely different Pi. It turns out that I was making a few mistakes:

  1. You absolutely have to use the 32bit version of Raspberry Pi OS lite. Not 64 bit. Not the default version that you click on accidentally. 32bit. Lite. No exceptions.
  2. I was getting owned by my own paranoid network security.

You see, the monster that we fear most is the one that we see in the mirror. Spies sweep for bugs, thieves keep things in safes, and hackers enable AP-Host isolation on their wireless networks. Host isolation keeps devices that are connected to an access point from talking to each other. They can see and talk to hosts that are on the same wired network as the AP, so you can connect to servers. The reverse is also true, servers on the wired network can see and talk to hosts that are connected to the AP. What absolutely doesn’t work with AP-Host isolation is an iPad that is connected via WiFi connecting to a RaspberryPi that is also connected to WiFi. You get nothing. Good day sir.

One way to remedy this situation is to use a server on the wired network as a jump box for SSH, and some Stupid SSH Tricks(tm) for mapping port 80 on the Pi to a local port on your iPad or laptop. Rather than deal with the keyboard situation on the iPad, I just used PuTTy on my windows laptop for the initial setup.

Begin the RaspAP install by running the quick installer:
curl -sL https://install.raspap.com | sudo bash

(I’m a Debian guy that still uses su instead of sudo, so I probably over use sudo in all of these examples.)

At this point, the order of operations is critically important. DO NOT START THE HOTSPOT! You need to configure the WiFi Client AP Mode under Hotspot|Advanced before you do anything. You can’t change the AP Mode while the AP is running, and running the AP shuts down wlan0 on the Pi, so you can’t connect to the Pi while the AP is up, and shutting off the AP cuts off your access to the Pi. I had to re-image my SD card a few times because of this error. I guess you can fix this using the wired Ethernet, but I haven’t figured out how.

To enable WiFi Client AP Mode, open the hotspot menu, set the SSID and pre-shared key options for your AP, and then click “save”. Then enable the WiFi Client AP Mode under the Advanced tab. THEN AND ONLY THEN can you start the hotspot.

Now configure hostapd to start at boot:

sudo update-rc.d hostapd defaults
sudo update-rc.d hostapd enable

Then reboot the Pi to make sure the AP comes up:

sudo shutdown -r now

It will take a few minutes for the AP to be visible to the iPad, and once the AP is visible, you should wait for a minute or two before connecting.

The thing to remember from here on out (that you can add as a host in Blink) is that when you are connected to the Pi AP, the Pi’s static IP is 192.168.50.1. From there you can add those sweet delicious network tools that are missing from iOS. My next post will cover some of those tools.

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