Notes by Jeff N2XGL, Version 1.0, Dated 2019-02-20
By default, the EOSS SDR Tracker is configured to automatically recognize wired Ethernet LAN connections. When a network cable is plugged in, the tracker computer will bring up the Ethernet interface, request an IP address via DHCP, and update the routing table with a known gateway to the Internet. If the WiFi on the tracker computer is providing a local hotspot, then all clients on the WiFi hotspot will also be routed to the Internet.
It is also very easy to connect cellular data modems and smart phones to the SDR tracker computer in order to get Internet access. The baseline Ubuntu 18.04 operating system and the Network Manager service provide a wide range of drivers and configurations for many cellphones and cellular data modem access points. Most modern smart phones and many access points will provide a virtual Ethernet-like interface over a USB connection, which the SDR Tracker computer treats just like an Ethernet cable being plugged into the unit. Apple iPhones and iPads require an additional one-time step to have the computer recognize and connect (see below).
Begin by placing your smart phone into "personal hotspot" mode, which depends somewhat on the individual phone and is beyond the scope of this application note. Then connect your smart phone to the SDR tracker computer with a USB cable, plugging in to any available USB port on the computer. That's it! After a couple of minutes, a network connection will be established. You can read below about how to list network connections and devices.
To connect to Apple iPhones and cellular-enabled iPads, you need to install some additional software packages onto the SDR Tracker computer. Once this is done, connecting an iPhone or iPad in "personal hotspot" mode will behave automatically.
To install the package, begin by connecting the SDR Tracker computer to the
Internet by any other means (e.g. Ethernet or WiFi). Follow the
EOSS-SDR-Tracker-Wifi.md guide
for getting your system connected to a local/home-based WiFi network or connect
to a local network using an Ethernet cable inserted into one of the RJ45 ports.
Log into the tracker computer with the eosstracker account.
At the command prompt, enter the following command:
sudo apt-get -y install ipheth-utils
You will have to enter your password again in order to perform the package installation as root.
Once the operation completes, you can turn your iPhone or iPad "personal hotspot" on, and then plug the in the Lightning-to-USB cable into the tracker computer.
The first time you plug in your device, you will be prompted to trust the new computer:
Click on "Trust" and you should be all set. From now on, whenever you plug in an iPhone or iPad with personal hotspot turned on, it should be recognzied and connected.
To check that USB tether devices have connected, enter the command
nmcli d
You will see a list similar to
DEVICE TYPE STATE CONNECTION
enp1s0 ethernet connected Wired connection 1
enp0s20u4c4i2 ethernet connected Wired connection 3
wlp2s0 wifi connected Home-wifi
enp3s0 ethernet unavailable --
lo loopback unmanaged --
In this case, enp0s20u4c4i2 is the USB-tethered phone. It emulates
an Ethernet connection, and it shows connected status.
To see the network connection status, enter the command
nmcli c show
and you will see an output similar to
NAME UUID TYPE DEVICE
Home-wifi f1f123ab-2889-473a-b881-893678ab3991 wifi wlp2s0
Wired connection 1 c0f3f448-5744-3345-9567-44c36a372130 ethernet enp1s0
Hotspot b734f4bb-b48c-4983-b869-e9872bc7457d wifi --
Wired connection 2 86987fe6-b834-3983-a908-96aac5347dd8 ethernet --
Wired connection 3 4df3cd6c-cfd2-3223-bs46-88cab45dc5c4 ethernet enp0s20u4c4i2
You can see that the device enp0s20u4c4i2 is connected.
Other commands such as dmesg will show you the kernel messages when you
plugged in the personal hotspot, and route -n will should you the
routing tables, including Internet gateway address information.
There are a large number of USB devices that connect to the Internet over cellular data. USB thumb-drive style cellular modems (often used with laptop computers) may not present themselves as emulated Ethernet over USB and instead present as a high-speed modem "mobile broadband" device. The configuration for mobile broadband devices may not be automatic and is not included in this application note.