Introduction

Establish 3G connectivity from Raspberry Pi using USB Dongle (MS 2131) with SORACOM Air SIM.

Preparation

• Raspberry Pi
• USB Dongle (Huawei MS2131)
• SORACOM Air SIM for Global (Ready/Active status)

Step 1: Insert SORACOM Air SIM to USB Dongle (MS 2131)

Slide the front cover to remove it from your dongle.

Cut SIM Card into Standard SIM. (Please be careful not to cut into the smaller size)

Put your SIM card into the card slot (as shown in the image below).

Replace the front cover and slide it back into place.

Step 2: Configure Raspberry Pi for USB Dongle

Log into your Raspberry Pi and install network-manager package

Tip: If you are not familiar with Linux Command Line. This is a good list of cmd to remember: Common Linux Command Line

Command

sudo apt-get install network-manager

Results

...
Need to get 7,709 kB of archives.
After this operation, 20.8 MB of additional disk space will be used.
Do you want to continue? [Y/n] y

Type 'y' and enter

...
Setting up ppp (2.4.6-3.1) ...
Setting up iputils-arping (3:20121221-5) ...
Setcap worked! arping is not suid!
Processing triggers for libc-bin (2.19-18+deb8u7) ...
Processing triggers for dbus (1.8.22-0+deb8u1) ...
Processing triggers for systemd (215-17+deb8u7) ...

Once Network Manager has been installed, create the 3G Dongle connection

Command

sudo nmcli con add type gsm ifname "*" con-name soracom apn soracom.io user sora password sora

Results

Connection 'soracom' (3cbecb73-2f6c-48f9-819a-3e233408d4a0) successfully added.

Reboot the Pi

Command

sudo reboot

The Pi will be rebooted and your current SSH terminal will be disconnected.

Please reconnect to the Pi using assigned IP address (id/pwd = pi/raspberry).

plug in your USB Dongle and you should get a ppp0 interface. (This is your Cellular connection)

When it is connected via 3G, the USB dongle shows solid blue light.

Command

ifconfig ppp0

Results

ppp0 Link encap:Point-to-Point Protocol
inet addr:10.237.184.147 P-t-P:10.64.64.64 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:7 errors:0 dropped:0 overruns:0 frame:0
TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:106 (106.0 B) TX bytes:171 (171.0 B)

Your Pi is now connected to the cellular network and will automatically connect each time a Dongle is plugged in or Linux restarted. It will also automatically reconnect in case the connection drops for any reason (for example, if a device moves temporarily out of range of a mobile network).

One thing to note is that by default, Cellular connection has lower priority than WiFi or Ethernet. This could potentially affect your ability to access your device remotely. To solve this we update the default route metric by creating a Network Manager script:

First, run the route -n command to see current Kernel IP routing table:

Command

route -n

Results

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.1.1     0.0.0.0         UG    303    0        0 wlan0
0.0.0.0         10.64.64.64     0.0.0.0         UG    1024   0        0 ppp0
10.64.64.64     0.0.0.0         255.255.255.255 UH    0      0        0 ppp0
169.254.0.0     0.0.0.0         255.255.0.0     U     304    0        0 wwan0
192.168.1.0     0.0.0.0         255.255.255.0   U     303    0        0 wlan0

wlan0 interface will be used because of the priority (the order).

Download and install Soracom ppp route metric script:

Command

sudo curl -o /etc/NetworkManager/dispatcher.d/90.set_ppp_route_metric https://soracom-files.s3.amazonaws.com/handson/90.set_ppp_route_metric

Make sure it is executable

Command

sudo chmod +x /etc/NetworkManager/dispatcher.d/90.set_ppp_route_metric

This new script will run every time you reconnect a Dongle or reboot your pi, with it, you’ll be able to connect to it via Ethernet or Wifi while at the same time use Cellular as your default connectivity. Run it manually or otherwise reboot to activate it

Command

sudo /etc/NetworkManager/dispatcher.d/90.set_ppp_route_metric ppp0 up

After running the script, run route -n to see the routing table:

Command

route -n

Results

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.64.64.64     0.0.0.0         UG    0      0        0 ppp0
0.0.0.0         192.168.1.1     0.0.0.0         UG    303    0        0 wlan0
0.0.0.0         10.64.64.64     0.0.0.0         UG    1024   0        0 ppp0
10.64.64.64     0.0.0.0         255.255.255.255 UH    0      0        0 ppp0
169.254.0.0     0.0.0.0         255.255.0.0     U     304    0        0 wwan0
192.168.1.0     0.0.0.0         255.255.255.0   U     303    0        0 wlan0

Notice that new ppp0 routing is now higher priority (order) in the table. The ppp0 interface will be used for any destination IPs.

Please open another terminal to the Pi and run the following script to confirm the Pi is connected via ppp0 interface over SORACOM network:

Command

curl ifconfig.io

Results

xxx.xxx.xxx.xxx

look up this IP address:

Command

host xxx.xxx.xxx.xxx

Results

xxx.xxx.xxx.xxx.in-addr.arpa domain name pointer ec2-xxx-xxx-xxx-xxx.eu-central-1.compute.amazonaws.com.

If you see the IP is coming from amazonaws.com, you are connected via SORACOM.

Congratulations!!