Share your Mac Internet Connection with a Pi-Star Hotspot

In this tutorial you’ll see the steps I took took to share the Internet connection from my Mac with my Pi-Star running on a Raspberry Pi Zero W. In some areas my Wi-Fi connection isn’t great and this is a way that I can use the wired Ethernet connection that my Mac uses.

Use the Pi-Star Dashboard to access the SSH Terminal app. I won’t go into how to use command-line editing tools in this tutorial. I use VIM to edit the files. Access the SSH terminal from the Pi-Star Dashboard > Configuration > Expert > SSH Access page. Log in as pi-star (default password is: raspberry).

Enter Read-Write Mode

By default Pi-Star runs in read-only mode and since we’ll be changing a few files, make sure to enter read-write mode by entering the following command:

$ rpi-rw

NOTE: the $ shown above is just indicating the terminal prompt.

Enable Raspberry Pi to run in Gadget Mode

Edit /boot/config.txt

Add the following line to the end of the file:

dtoverlay=dwc2

Edit /boot/cmdline.txt

Add the following (on the same line) right after rootwait:

modules-load=dwc2,g_ether

After the change, your /boot/cmdline.txt file should look something like this (all one line):

dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait modules-load=dwc2,g_ether fastboot noswap ro

Edit /etc/network/interfaces

Add these lines after the iface eth0 net manual line:

allow-hotplug usb0
iface usb0 net dhcp

Restart and Configure Internet Sharing

1. Shut down and power off your hotspot in your normal way
2. Plug in a USB cable from your Mac to your hotspot using the Micro USB port marked as USB (not the power port)
3. Wait for your hotspot to boot
4. Open the System Preferences app on your Mac by selecting it from the  Menu at the top left of your Mac
5. Go to the Sharing settings
6. Inside the Internet Sharing section a new option (RNDIS/Ethernet Gadget) should appear as one of the options
   • If it does not appear, wait for a few minutes and reboot the hotspot again. On one of my computers it took a couple reboots.
7. With the Internet Sharing option unchecked, check/enable the RNDIS/Ethernet Gadget port
8. Turn Internet Sharing back on
9. Reboot your Pi-Star Hotspot again
10. Check to see that your hotspot is using the shared connection from your Mac by either:
    • Transmitting from your digital radio and observing the bottom part of your Pi-Star screen (it should show usb0: <IP Address>)
    • Use SSH Access to print out the network interfaces to verify that usb0 has an IP Address by running the following:

$ ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
2: usb0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 86:03:63:9f:db:47 brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.5/24 brd 192.168.2.255 scope global usb0
       valid_lft forever preferred_lft forever
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether b8:27:eb:68:96:bc brd ff:ff:ff:ff:ff:ff
    inet 192.168.230.6/16 brd 192.168.255.255 scope global wlan0
       valid_lft forever preferred_lft forever

Change your Hotspot Fallback Mode Password

When you connect your Pi-Star hotspot through Internet sharing, that won’t stop the Wi-Fi from automatically trying to connect. If it finds one of your configured Wi-Fi networks it will also connect to that. If it doesn’t, it will put the Wi-Fi radio in fallback mode (unless you’ve disabled Auto AP in the dashboard). I like the ability to have the fallback mode available if I ever take my hotspot some place new and want to easily connect. But, changing your Pi-Star main password does not change your fallback Wi-Fi password. To do this (a very good idea), edit /etc/hostapd/hostapd.conf and change wpa_passphrase to something besides the default of raspberry. Just make sure you remember the password.

Other Notes

I haven’t taken any steps to disable Wi-Fi and so you’ll see above that my network interfaces also shows a Wi-Fi connection. From the Pi-Star dashboard you should see activity once you connect to a talkgroup. In my case, I no longer see a high loss percentage.

If you have any suggestions or additional tips, please let me know in the comments or shoot me an email.