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+# From [FnasBas](https://github.com/FnasBas)
+This is based on [this comment](https://github.com/mikebrady/shairport-sync/issues/482#issuecomment-402543454).
+
+Here's a starting point. I hope it is useful to someone :)
+
+# Alternative car setup approach
+This is offered in the hopes it will be useful to someone. The background is that, besides all the advantages of WiFi/AirPlay over Bluetooth,
+when travelling my phone is my only internet connection, and I want to be able to share it with other devices.
+Like an iPad or laptop. I may also want to be able to send audio to the car Shairport Sync service from my other devices while
+simultaneously having internet access on them, via the phone.
+
+So the basic idea is just to turn the table on which device acts as the Access Point for the WiFi. Which works perfectly well.
+The prerequisite is that your carrier/contract allows tethering, as otherwise you won't be able to have your phone act as a WiFi Access Point.
+I also think this is a bit simpler to set up as you don't need to set up `hostapd` and a DHCP server on the Pi.
+The drawback is that you need to do a gesture and tap a button on the phone to make its network discoverable when entering your car.
+
+## Phone configuration
+Enable tethering on your iPhone with a secure passphrase. 
+
+## Raspberry Pi configuration
+Set up Shairport Sync according to your needs and instructions found elsewhere.
+
+### Network
+Configure your Raspberry Pi with only one WiFi network. Through experimentation I found that if I was in the vicinity of my home network,
+the Pi would not reliably choose the iPhone's WiFi network even though it was prioritized over the home network.
+And it seems `wpa-supplicant` in general is a bit difficult to get to roam between different WiFi networks once it's decided on one.
+
+Example of `/etc/wpa\_supplicant/wpa\_supplicant.conf`
+
+```
+ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
+update_config=1  
+country=SE  
+network={  
+       priority=3  
+       ssid="My unique clever wifi network name"  
+       psk="My very secure wifi key"  
+}  
+```
+
+### Read only root filesystem
+By configuring your Pi to have a read only root filesystem, you need not ever worry about an improper shutdown of the OS
+causing the Pi to fail to boot. You will also be sure that the Pi always boots to a predetermined state.
+And you will eleminate wear on the SD card completely except for when modifying the system.
+This will result in a very reliable AirPlay service. 
+
+These instructions are a bit old but a good starting point: (https://openenergymonitor.org/forum-archive/node/5331.html) 
+
+In addition to what's laid out there I've also:
+
+* Added the `/boot` fs to be mounted read-only and modified the rpi-rw/ro scripts and `/etc/fstab` accordingly
+* in `/etc/systemd/journald.conf`, set `storage=volatile`
+* As the `systemd` `ntp` client is hard-coded to use a specific path for its book keeping, I've disabled that and installed `ntpd`
+and set the drift file to `/tmp/drift`
+* Your DHCP client will complain that it can't write its lease to a file. You can work around this by setting it to write its lease
+to a file in `/tmp` or disregard it as it will work fine in any case.
+
+In my case I do not use a car stereo but go straight Pi>Dac>Power amplifier. So I've also set up EQ with `alsa`, and a relay module to a
+GPIO pin and some scripts that run on session start/stop that turns the power amplifier on and off accordingly.
+But this could turn in to "How I set up my car audio" rather than offering an alternative to [what's currently suggested
+for a car installation](https://github.com/mikebrady/shairport-sync/blob/master/CAR%20INSTALL.md).
+So I stop. ;)
+
+## Using it
+Make your phone's network discoverable. In iOS 11 there's a shortcut for this – swipe up and hold down on the connectivity section.
+There's a button to turn on Internet Sharing.
+In my experiments the Pi connects almost instantaneously to this network and a few moments later the AirPlay service offered by Shairport Sync
+will become visible.
+
+## Changing and Maintaining it
+Make your phone network discoverable. The Pi connects. Connect your laptop to the same network.
+The iPhone does not appear to resolve host names from one tethered device to another so you need to `ssh` to the Pi's IP-address.
+There's a number of ways to find the Pi's IP-address:
+
+* You can check your laptop's IP and try subtracting or adding from the last octet
+* Use a `zeroconf/avahi` browser tool and locate the AirPlay service and find the IP address that way
+* Use `nmap` or other similar utility to scan for the Pi
+
+`ssh` to the Pi
+```
+rpi-rw
+change stuff
+rpi-ro 
+```
+
+### Further thinking
+Other Apple devices can wake the WiFi Access Point on the iPhone. My conclusion is that this must be accomplished via Bluetooth,
+but Apple doesn't seem to be open spec on this subject as all I've been able to find is that certain devices, when paired with Bluetooth,
+connected to iCloud etc. etc. will offer this functionality.
+Being able to reverse-engineer what Bluetooth communication is actually done in order to turn on the WiFi Access Point on the phone
+would mitigate the drawback of this method, as the Paspberry Pi could be constantly looking for the phone via Bluetooth and
+enabling Internet Sharing that way.