psendurance -- "Packet-switched endurance"

Introduction

Peristent mobile data connection using ofono.

Mobile data connections, such as 3G and UTMS, break down every now and then. This poses a challenge for autonomous devices, small servers that connect to Internet using mobile data connections. There continous connection is desired. This script tries to open such a connection and re-open it every time the connection is lost.

This script is intended for autonomous devices that connect exclusively to a mobile network. It is not intended to be a connman replacement. Only one modem with one pre-defined internet context is currently supported.

Currently this is developed and tested on a Raspberry Pi running Raspbian, and a Huawei E367 USB dongle.

At the present state it's quite experimental. Use it at your own risk. Ideas, improvements, patches and pull requests are welcome.

License

psendurance is released under the terms of GPLv2, see COPYING.

Requirements

The following Raspbian packages should be installed:

• ofono
• python
• python-dbus
• python-gobject
• For convenience: usb-modeswitch, usb-modeswitch-data

You can install these in the usual way:

$ apt-get install <package-name> 

Usage

Plug in a 3G dongle with a SIM without a PIN. Make sure that the ZeroCD mode is skipped by usb-modeswitch and ofonod sees the actual modem device. (See ofono test scripts, ./list-modems below.)

$ python psendurance.py 

and hope it works.

Troubleshooting and debugging tips

ofono test scripts

Download the ofono package, untar it and go to /tests/ directory. There you can find many python scripts, which can be used to manually command and test out your modem.

For example, this script executes roughly the same operations as:

$ ./enable-modem
$ ./online-modem
$ ./set-roaming-allowed
$ ./activate-context

List modems:

$ ./list-modems

List contexts:

$ ./list-contexts

Create an internet context:

$ ./create-internet-context <APN> [username] [password]

Running ofono in debug mode

Ofono's debug output is fairly verbose and informative. You can see it by running the ofono daemon manually. Shut down the ofono system daemon first:

$ sudo /etc/init.d/ofono stop
$ sudo ofonod -nd
(hit Ctrl-C to shutdown this, when done)

$ sudo /etc/init.d/ofono start

Use dmesg

Looking at kernel output is helpful for determining whether a 3G dongle is in the right mode. If you're seeing just lines with "scsi", the dongle is in ZeroCD mode. If the dongle gets into a modem mode, you should see lines informing about creation /dev/tty* device nodes, such as /dev/ttyUSB0.

"Missing support for TUN/TAP devices"

Seen in ofonod's debug output.

In Raspbian, tun module is not loaded by default. You can load it manually:

$ sudo modprobe tun

"GPRS is not attached"

Seen when trying to call ./activate-context.

One reason for this is that your ISP uses roaming network of another ISP, and this is not allowed by ofono's default settings. For example, Saunalahti in Finland uses Elisa's network. RoamingAllowed must be enabled explicitly. In ofono test scripts (see above):

$ ./set-roaming-allowed

You might want to be careful, if you're using this near your country borders or a foreign country. Watch out those roaming fees, and make sure you're registered to the correct network.