Microblog : A very long article Wikipedia article on the orientation of toilet paper [7 jun à 22:52] [R]

Mardi, 9 février 2010

User Identification through Web Browser User-Agent

Traduction: [ Google | Babelfish ]

Catégories : [ Informatique ]

I found las year that 33 bits are enough to uniquely identify someone.

Now I just read that the browser's User-Agent field provides 5 to 15 bits of identification (10.5 bits on average). If you add zip code, geolocation, it becomes nearly enough to track people perfectly.

With EFF's Panopticlick, I know that my browser provides at least 16.12 bits of identification. The identifying criteria are the User-Agent and HTTP_Accept fields, available plugins, time zone, screen size, system fonts, cookies enabled/disabled and so-called super-cookies. The most scary part of the report is the statement that “Your browser fingerprint appears to be unique among the 71,157 tested so far.”

Without Javascript, my browser still provides 16.13 bits, due to the HTTP_Accept header and User-Agent.

[ Posté le 9 février 2010 à 12:56 | 1 commentaire | ]

De l'âge du pu er

Catégories : [ Thé ]

« Dès qu'il s'agit de Pu Er et autre chinoiserie … tu peux être sûr qu'il y a un truc pas très net quelque part !!! Jamais très clair tout ça ;-) »

Ainsi s'exprimait un amateur éclairé de pu er (qui tient à rester anonyme). Il avait mis son expertise à mon service pour goûter mon pu er mystère (voir tout au bas de l'article). Il confirme qu'il s'agit du pu er « cuit », mais qu'à son avis il ne date ni de 2005 (comme la date de production sur l'emballage le laissait penser) ni probablement de 1990 comme le vendeur me l'avait annoncé:

« Un cru de 2005 serait plus incisif, moins rond, nettement moins moelleux. De même s'il datait de 1990, il aurait en théorie plus de charpente, plus de corps avec des notes plus camphrées. Il est donc probable que cette galette ait été fabriquée en 2005 mais avec des feuilles d'une dizaines d'années, guère plus. … En fait, il me rappelle curieusement une galette de la Maison des Trois Thés qui date de 1994. Une année qui pourrait tout compte fait assez bien lui correspondre ! »

Mais suite à une question de ma part, il avoue que « 4 années de vieillissement supplémentaire n'influent pas trop sauf en cas de stockage humide », ce dont je déduis que le thé pourrait dater de 1990 mais qu'il ne s'est pas bonifié de manière notable durant ses quatre dernières années de vieillissement.

En conclusion, je vais essayer de suivre son conseil, même si je sens mon esprit analytique se rebeller à cette idée : « Profite simplement de tes Pu Er et ne te pose pas trop de questions, de toute façon c'est un monde tellement complexe et opaque qu'il vaut mieux se contenter d'apprécier ce que l'on a sans en savoir plus car on risque toujours d'être déçu. » En d'autres termes, si c'est bon, c'est bon, et si c'est pas bon, c'est pas bon. Lapalisse n'aurait pas dit mieux.

[ Posté le 9 février 2010 à 12:15 | pas de commentaire | ]

Lundi, 8 février 2010

The Definite New ADSL Modem

Traduction: [ Google | Babelfish ]

Catégories : [ Informatique ]

End of the new ADSL modem story. I sat on my principles and bought last Saturday an A-Link RR24AP(d) at Gigantti, even though it runs Linux (yes!) without publishing the source code (boo!). It cost me 20 EUR more than what it would have cost at Multitronic.fi, but I guess that's what it cost to get it immediately.

The RR24AP(d) is not perfect either: its DynDNS client is updating its DNS record even though the IP address doesn't change (I got banned temporarily by DynDNS for that; I restarted the DynDNS daemon running on minikone and disabled the one in the router).

Moreover, I wanted to use its telnet/ssh menu-based interface for enabling/disabling the WLAN from the desktop (I wrote a docklet for that with a wrapper script for hiding the protocol stuff), but although enabling works, disabling doesn't work. I had to use the Web interface instead. An additional nice discovery is that although the main menu offers choices numbered 1 to 10, when you choose 0, you get a root shell. I haven't found a way to enable/disable the WLAN from the shell, hence the wrapper script for the Web interface.

[ Posté le 8 février 2010 à 22:23 | pas de commentaire | ]

Vendredi, 5 février 2010

More ZyXEL Troubles

Traduction: [ Google | Babelfish ]

Catégories : [ Informatique ]

Part 2 of the new ADSL modem story.

This is how it goes: reboot the modem, connect to its telnet server. The TCP window is 2048 bytes long. Everything works fine. Telnet again: the TCP window is now 1024. Actually, it shrunk to 1024 already on the FIN/ACK packet sent by the router when closing this first telnet session and stays like this for all the subsequent connections. During those connection, each ACK packet it sends is followed by a second ACK where it resets the window size to 1024 bytes. After some time (this is the tricky part, I have no idea how time or idleness affects it), when telneting again, some TCP packets are lost, the client side has to retransmit them. Insist a bit more, and there are more and more packets which don't get acknowledged. Eventually, the telnet server may become non-responsive and the whole device stops responding to pings. Reboot the modem.

Whether using the forwarded port from the WAN to the client machine on the LAN is involved or not in prooking this behaviour is not known, more investigation needs to be done.

I contacted ZyXEL, they asked me to return the device. Let's see if they are able to reproduce the problem.

[ Posté le 5 février 2010 à 17:31 | 1 commentaire | ]

Jeudi, 4 février 2010

New ADSL Modem

Traduction: [ Google | Babelfish ]

Catégories : [ Informatique ]

The old A-Link RR64, Linux 2.4-based ADSL modem and router has been dying slowly for the past eight months or so, and when the “alarm” LED went suddenly on, I decided it was time to get a new piece of hardware before that one broke down completely. Since it had a hard time booting up after the power had been down, it was a good idea anyway.

After long discussions with my colleagues, I decided to buy a ZyXEL Prestige 660WP-D1, with an integrated WLAN base station. It's not based on free software, but the equivalent linux-based model by A-Link doesn't respect the GPL regarding the distributon of the source code (it actually doesn't even mention it's based on Linux), so I wasn't going to give my money to those people anymore.

I spent the whole evening and half the night yesterday trying to set it up so that it replaces the old device in the network. First thing, the ZyXEL does't have a DNS server for the local network, so I had to setup one on the server there using dnsmasq (merci tontonth :) ). This means I cannot get the outside DNS server's address from the ISP anymore (the router is unwilling to serve as a DNS proxy while at the same time propagating the dnsmasq's address through the DHCP configuration) but I have to set it up statically in dnsmasq. I hope it doesn't change its address every two weeks…

The second problem was that the NAS I use for backups is unable to get its IP address from the ZyXEL, so I had to set a static one.

But the weirdest of the weirdest, is that the machines connected through the WLAN were not able to connect to the ones on the LAN, which is a bit of a problem since the dnsmasq is on the LAN. After a long time reading the docs, I found in the latest firmware's changelog that the following bug had been fixed: 22. WLAN and LAN can not communicate with each other when the admin password is changed in the GUI. The new firmware indeed fixed the problem, but what screwy software design makes the bridging between two networks dependent on the admin's password and the GUI? This is bound to be a problem for any user who knows that default passwords must be changed, since the first time you connect to the Web interface as admin, it forces you to change the password.

Well, it seems to be working now. Let's cross fingers.

[ Posté le 4 février 2010 à 12:21 | 1 commentaire | ]