Patrick’s Blog(2)

The new PR 1.2 firmware release for the N900 was just released and it’s time to upgrade. Then you bump into your first challenge: how to backup your SMS messages on the N900? Nokia’s PC Suite only backs up Contacts etc. but not your SMS messages. And Ovi Suite still does not support the N900 (what’s up with that Nokia?!).

So how do you backup your SMS messages (and Contacts, Calendar, Tasks, Notes, Bookmarks and Settings)?

Here is how:

1) make sure your N900 has a full battery or is plugged into the charger

2) on your N900 start the Backup application

3) select “New Backup”, fill in a name like N900_Backup_<date> and press “Proceed”

4) in the next screen make your selection or leave all enabled and press “Select”. Make sure at least “Communication and Calendar” is selected as that one contains your Contacts, Calendar, Tasks, Notes and SMS messages

5) wait for the Backup to finish after which you are returned to the main Backup screen where you see your shiny new backup

6) copy the backup (directory + contents) from your N900 to your PC

7) upgrade the N900 to PR 1.2

8) copy the backup (directory + contents) on your PC to your N900. The location on the N900 is /home/user/MyDocs/backups

9) start the Backup application. yuo should now see your backup listed

10) press “Restore”, select your backup and voila all your data should be restored

Disclaimer: no guarantees, this is how it worked for me. Your mileage may vary.

The New York Times has an excellent article showing an overview of all (current) Facebook privacy settings. To protect your privacy you should use a setting of “Only Friends” or “Only Me” (via Custom) and disable pretty much every kind of sharing. If you do not understand what a setting means and you value your privacy then be sensible and disable the setting.

The last and quite important one in the right side in the picture called ” Facebook Ads Page” can be found (when already logged into Facebook) by clicking on Account then Account Settings and then select the tab on the right side called Facebook Ads and set *both* options (at the top and bottom) to “No one”. You have to do that separately for each one. So select “No one” in the top option and click “Save Changes” and then do it again for the bottom one.

Or you could just delete your Facebook account by clicking on Account then Account Settings and then select Deactivate Account. Once you have done that, do *not* log in to Facebook for at least 14 days or else Facebook will magically reactivate your account.  The Facebook help page on this subject can be found here.

Remember, Facebook’s business is your information so the more information they have, the more money they can make.

Assumptions:

• Fedora 13 x86_64 is installed and updated with yum update
• et-linux-2.60.x86.run is installed
• the et-2.60b.zip patch is installed
• kmod-catalyst is installed from rpmfusion.org

There are two parts to make this work: Graphics and Sound

Graphics:

• get xorg-x11-drv-catalyst-libs.i686 rpm from rpmfusion.org (note the .i686 extension. It must be the same version as the x86_64 one you previously installed)

Sound:

You need to add a couple of lines to /etc/rc.local to make sure sound works properly:

/sbin/modprobe snd_seq_oss
/sbin/modprobe snd_mixer_oss
/sbin/modprobe snd_pcm_oss
echo "et.x86 0 0 direct" > /proc/asound/card0/pcm0p/oss
echo "et.x86 0 0 disable" > /proc/asound/card0/pcm0c/oss

Alternatively you could use et-sdl-sound.

Other solutions or improvement are most welcome in the comments.

Let’s say you have an Asterisk server that listens on the standard UDP port 5060 and want to use the VoIP client on for example your shiny new Nokia N900. You configure the VoIP client and everything works as advertised via your local WiFi link.

Next you also want to use the 3G/3.5G Internet link on your phone. Security conscious as you are you run into a small problem. Using the standard UDP port 5060 is not a smart thing to do as the usual evil suspects are scanning boxes across the Internet for port 5060 so they can try to hack into it and make free calls. So you need to use a different UDP port. Here’s were the problem starts.

Asterisk can only listen on one port and one IP address. Pretty silly I know but that’s the way it is (unless you switch to FreeSWITCH). Your VoIP client also supports only one UDP port. You could create two profiles in your VoIP client but that’s ugly and not what we want.

We really just want to use a UDP port that is not 5060 that can be used on the local LAN and on the 3G/3.5G link while Asterisk is still listening on UDP port 5060. The solution is simple: on the box running Asterisk add one IPtables port forwarding rule to your firewall. Here’s how to do it:

You need root privileges for all steps.

Make sure your firewall is running before continuing with the next steps:

# service iptables start

Next add the portforwarding rule to IPtables where:

INTERFACE = the interface of your Asterisk box (example: eth0)
IP = the IP address of your Asterisk box (example: 192.168.43.157)
OTHERPORT = the port you configured in the VoIP client (anything but 5060, example 12345)

# cd /etc/sysconfig
# cp iptables iptables.backup
# iptables -t nat -A PREROUTING -p udp -i <INTERFACE> -d <IP> –dport <OTHERPORT> -j DNAT –to <IP:5060>
# service iptables save
# service iptables restart

Now check your shiny new IPtables portforwarding rule:

# service iptables status

And you should see something like this (IP addresses are just examples):

Table: nat
Chain PREROUTING (policy ACCEPT)
num target prot opt source     destination
1   DNAT   udp  --  0.0.0.0/0  192.168.43.157 udp dpt:12345 to:192.168.43.157:5060

To enhance security I would recommend to limit the IP ranges from which the VoIP client can connect by adding IP restrictions to your VoIP client’s profile in /etc/asterisk/sip.conf:

deny=0.0.0.0/0.0.0.0
permit=<IP range1 of GSM provider>/<netmask>
permit=<IP range2 of GSM provider>/<netmaks>
permit=<IP range3 of GSM provider>/<netmaks>

Testing the various codecs using the 3G/3.5G link on my N900 it seems that the iLBC codec at 40ms gave the best results (allow=ilbc:40 under the VoIP client’s profile in /etc/asterisk/sip.conf). Alaw was the clearest but every second letter of words I spoke were dropped. Same for AMR and G.729. This seems to be caused by high packet loss. On the N900 I ran mtr-tiny and saw packet loss as high as 49% and about 30% consistently (WTH?). This might be caused by shaping and prioritizing of UDP by the Telco. Once I have replaced Asterisk with FreeSWITCH I will test again using UDP and TCP to see if using TCP makes a difference.

For even more security use TLS with self-signed client certificates. TLS is supported on Asterisk 1.6.x but I do not know if Asterisk 1.6.x also supports authorization based on client certificates. Again, if you want advanced secure functionality like that you should probably look at FreeSWITCH.

I was going through some really old stuff and found a picture of my first car. A silver-grey metallic Renault 5 GTL with bright orange upholstery which I bought in The Hague from a friend of a friend for FL 125 Guilders (less than 60 euros). Here is a picture:

My first car: a Renault 5 GTL

I have fond memories of this car. Obviously the freedom it provided. It drove well too except that the engine would always overheat. The car had a temperature meter and it even worked so I knew when to stop which was after about 20km. To get going again I had to release some of the pressure by carefully opening the cap of the cooling system. Since I had little experience with car engines I couldn’t figure out what was causing it. It took me quite a while before I understood that it was a broken pressure valve in that same cap… Nevertheless this didn’t bother me as I had a car that took me places, albeit with some stops on the way.

At some point the water pump decided to pump the water on the street instead of through the system. That really needed fixing so I got a replacement pump at the car junkyard for 10 Guilders (less than 5 euros) and in the midst of winter removed the old pump and installed the new one. At freezing temperatures this wasn’t fun but in the end I succeeded and I was mobile once again.

After about a year of being my partner in crime the elements won. Due to extensive rust the left rear suspension pretty much detached from the chassis and that was the end of it. I remember driving her on a beautiful day to the junkyard where my little Renault met her final resting place.