WordPress update

After patiently backing up the database and files of this blog, I upgraded from WordPress 2.8.5 to 4.7.2 version. The migration was difficult. By the way, I upgraded from PHP 5.1.3RC4-dev to 5.6.8 by updating the .htaccess file. A big thank to this link : http://additifstabac.free.fr/index.php/deploiement-php-5-6-8-beta-serveurs-pages-perso-free/.

Tags: wordpress

My first Android app

This quick tutorial will show you how to compile, install and run your first Android application. It has been tested on Ubuntu 12.04

Ce rapide tutoriel vous montrera comment compiler, installer et lancer votre première application Android. Il a été testé sous Ubuntu 12.04.

Tags: Android

WiFi propagation model

For those interested, here are the results of my research in order to properly compute WiFi propagation (at 5 GHz) over ground without any trees, obstacles or whatever. Fading has been observed and I’d like to find out a formula that allows to compute it :

1. Few base concepts regarding radio propagation : http://www.csdptt.org/article410.html (in French)
2. Rice model propagation (mentioned in the previous document) : http://flattop.its.bldrdoc.gov/itm.html

Stay tuned!

Tags: wifi

Convert your Android into a GPS for Linux

Problem description:

I want to use my Android phone as a GPS for my Linux laptop. Here is a way to do it :

1. First, install BlueNMEA on your Android. Once launched, it listens on TCP port 4352 and sends NMEA strings to clients
2. Next, make sure your laptop and Android phone are connected via TCP/IP (for instance, they might be connected to the same WiFi AP or the Android phone is acting as a WiFi AP itself). You can check this by doing : telnet 192.168.1.1 4352 (Note : 192.168.1.1 is the default IP of the Android phone when acting as a WiFi AP)
3. Install gpsd on your laptop : aptitude install gpsd gpsd-clients. Since we are using gpsd 2.95, it can directly use the TCP/IP port. Otherwise, you need to use socat to relay data read from a TCP port to a special serial device : aptitude install socat ; socat TCP:192.168.1.1:4352 PTY,link=/tmp/gps
4. Start gpsd manually : gpsd -N /tmp/gps or gpsd -N tcp://192.168.1.1:4352 (add -D 2 for debug to see NMEA sentences)
5. Start xgps to show your position

Futher work :

1. Display your position on google maps using HTML5 geolocation API
2. Record your position with ms resolution and generate a KML file for Google Maps

Tags: Android, gps

iPhone default ssh password (with cydia)

If you just jailbreak your iPhone and installed cydia, there is a default ssh server running with the following password : ‘alpine’. To connect, just try (assuming your iPhone IP is 192.168.1.103) :

# ssh root@192.168.1.103
root@192.168.1.103’s password:
iPhone-de-benoit:~ root#

facebook

Here it is, I just got a facebook page whose address includes my name : http://www.facebook.com/benoit.papillault

POSIX standard

The POSIX-2004 standard is available online at : http://pubs.opengroup.org/onlinepubs/009695399/

In particular, the part regarding shell is here : http://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html

Happy new year 2011!

Happy new year 2011 to everybody ! and to start this new year, here is a small IPv6 tips to discover all IPv6 machines in a network :

# ping6 ff02::1%eth0

or

# ping6 -I eth0 ff02::1

according to the ping6 version.

This will return IPv6 addresses of all machines connected on the said interfaces. For instance :

64 bytes from fe80::4261:86ff:fe00:5a6: icmp_seq=1 ttl=64 time=0.016 ms

In order to connect to it with ssh, it’s all easy :

$ ssh root@fe80::4261:86ff:fe00:5a6%eth0

Installing OpenWrt on a Linksys WRT350Nv2

The WRT350Nv2 Linksys router is a 802.11bgn router (so, operating only in the 2.4GHz band). Its use with the original firmware is impossible since it is nearly impossible to connect using Wi-Fi, even with the use of the latest Linksys firmware (incredible isn’t it?). After installing OpenWrt within few minutes, the Wi-Fi connection has been working right away. Here are the installation steps: Read more…

Padding and alignment in mac80211

802.11 hardware adds padding on RX packets and removes padding on TX packets. Morever, mac80211, the generic Linux 802.11 software stack expects some alignments on RX packets. As such, software drivers need to deal with all those constraints to avoid spurious or missing bytes to show up.

Read more…