Mobile Internet access with GPRS

Anytime, Anywhere

By Marcel Hilzinger

www.sxc.hu

General Packet Radio Service (GPRS) is a communication standard for mobile phone networks that is designed for efficient data transfer. GPRS, which is typically faster than older, circuit-switched services, is not intended for voice communication but is, instead, tailored for activities such as email and web browsing over the mobile network. One important quality of GPRS is that it has the effect of being "always on." You do not have to dial a number in order to access GPRS services.

Many mobile phone networks now offer GPR Service to their users. A tool for called GPRS Easy Connect brings GPR Service to the Linux world. With Linux and GPRS Easy Connect, you are just one click away from mobile Internet access. The current version of this Perl program supports about 300 mobile phones and around 200 providers. You'll find a detailed list of supported devices and providers on the project homepage at [1].

At present, the developers Péter Simon, Gábor Pintér and Andrea Bravetti are working on version 3.00, which is based on GTK2 and supports UMTS and EDGE in addition to GPRS.

Perl One...

Installing Easy Connect should be quite simple if you are using any of the current Linux distributions. All you need in order to use Easy Connect is Perl and the perl-Tk, perl-libwww-perl, and perl-URI modules. The Suse Linux DVD has these packages. Users with other distributions may need to download one of the three Perl packages off the Internet.

Unpack the GPRS_Easy_Connect_253_Install.tar.gz package in a directory of your choice and enter su to become root (users with Suse Linux 9.2 or earlier can type sux to do this). Now change to the GPRSEC_Easy_Connect_253_Install directory and launch the install by entering sh  NSTALL. Click on Next, and confirm the terms of the GNU Public License before going on with the install. The next window displays a list of software components the program has discovered. If some of these components are tagged Error, you will need to install the missing programs. If you are looking for more details on dependencies, give the sh INSTALL -c command when launching the installer.

After fulfilling the dependencies, click Next and the installer will copy the required components to their final destinations; you can then select Finish to complete the install.

Setup

When you launch the program for the first time, by pressing [Alt]+[F2] and typing gprsec in the launcher, the main Easy Connect window appears (see Figure 1.) Click Setup GPRS Easy Connect to set up the mobile phone, provider, and connection type (Figure 2.)

Figure 1: You need to set up the mobile phone before launching Easy Connect.

Figure 2: To set up the connection, Easy Connect needs details of your phone, provider, and interface.

Select your phone in the list at the top, and select your provider in Choose your provider. Easy Connect displays a picture of the selected phone; this is a big help if you are not sure whether you have selected the correct model from the list. When you select a provider, the program automatically fills out your account data, such as your APN, user name, and password. These details are also available on the web at [2] or directly from your provider.

Use the Select the port option to select an interface for Internet access. The setting depends on your connection type. For Bluetooth devices, you will typically need /dev/rfcomm0. (See the box titled "Connecting your phone via Bluetooth.") Select /dev/ttyACM0 for USB connections. If you use a serial connection between your phone and your PC, enter /dev/ttyS0. If you use your phone's infrared port, select /dev/ircomm0. For information more on setting up Infrared connections, refer to the article in this issue titled "Directory Services: Managing your mobile phone with Gammu and Wammu."

If your interface type is not on the list, check Expert port scan and select the correct entry. You can use the Select your language entry if you prefer to change the interface language. Now click on OK/Save Data to display the Easy Connect main window again. The window has a Connect button that should allow you to connect. Easy Connect displays your IP address and data transfer rate statistics when the connection is up.

marcel@kim:~> hcitool dev
Devices:
      hci0    00:10:C6:29:2E:15

marcel@kim:~> hcitool scan
Scanning ...
  00:0E:07:BF:B4:C4    Z1010
  00:04:61:81:5C:6B    ubuntu-0

rfcomm bind 0 00:0E:07:BF:B4:C4

KERNEL="rfcomm*", NAME="%k" GROUP="uucp" MODE="0660" OPTIONS="resmgr"

rfcomm*:root:users:0666

device 00:0E:07:BF:B4:C4;

Usage and Tricks

For initial tests, you should launch Easy Connect as root. This gives you access to both /etc/resolv.conf (nameserver settings) and to the PPP daemon (chat scripts).

In our lab, our phone often reported problems with the Bluetooth connection, although the connection was active. This can be an expensive issue to resolve when you consider the price of mobile Internet services. To avoid unpleasant surprises, check your phone display after clicking Connect: most phones let you know that a connection has been established. For Bluetooth connections where your phone is not connected to your PC, you may even need to confirm the connection.

The /sbin/ifconfig command gives you a list of active network devices. As GPRS uses a PPP connection, you should see an entry for the ppp0 device if the connection is up. If you find this entry, you can type ping www.kde.org to see if you can contact the KDE project web server. At average GPRS speeds of 5-10 kbps, it can take a couple of seconds for the first response to start coming in. If ping responds with an unknown host error, your nameserver settings may be false. Try to ping the KDE website using the IP address in this case:

ping 80.232.38.131

If the IP address works, you need an entry of the form

nameserver IP address

to add at least one nameserver to the /etc/resolv.conf file. Check [2] for details of your provider's nameserver.

Now that you have successfully established a connection as root, you can drop your privileges and repeat the experiment using a normal account. The account you use will need execute permissions for /usr/sbin/pppd. The system administrator can grant a user the required permissions by entering the following command:

chmod +s /usr/sbin/pppd

In many cases, temporary problems can be resolved by switching your phone off and back on.

Unpleasant Surprises

Easy Connect makes child's play of setting up an Internet connection via a mobile phone. However, make sure that your mobile Internet connection does not burn a hole in your purse.

Most providers charge a monthly basic rate for the use of GPRS or UMTS - no matter whether you just want to test your connection using ping or download 1 MB of data. Packages with larger traffic volumes can cost up to 100 dollars per month. GPRS traffic can cost up to 20 dollars per MB of download volume. UMTS is cheap in comparison: expect to pay about 2 dollars per MB for UMTS service, depending on your contract. Many providers expect you to sign a 2-year contract in order to receive special services such as GPRS.