Tuesday, July 29, 2008

Android, the next big thing

While clients all over the world are lining up to buy iPhones, the next big hit make come from Google, in the form of Android. The iPhone is a tightly controlled platform whereas the Android platform is open. This difference may be deemed too geeky to make a difference. I beg to differ.

When people realize that they can make VoIP calls using nearby WiFi networks for free, or VoIP-to-PSTN calls for 20th of the current price, they'll go berserk.

There are two ingredients missing for this scenario to become reality. First, there must be an Android phone that people can buy off the shelf. Second, people need to start sharing their WiFi networks. This is not happening, or nearly not fast enough. Our minds are imprisoned by the notion that bits are scarce. Bob Frankston argues why this is the case but should not be.

Thursday, July 17, 2008

Putting a face on evil

Samir Kuntar is the perpetrator of a truly gruesome act of violence committed almost 30 years ago. He was released yesterday, on July 16, 2008 as part of a prisoner swap between Israel and Hezbollah. While the negotiations leading to his release are the subject of controversy, I am also quite concerned and shocked by the hero's welcome he received in Lebanon. The guy murdered a little girl with the butt of his rifle, not exactly the kind of person you'd want to root for, especially not in a mass rally.

For me, he represents the face of evil. His nazi salute of the crowd (see photo) just clinches it.

Taking a step back, Sun Tzu said All warfare is based on deception." This general principle also applies to the Arab-Israeli conflict. Since 1974, the political and psychological aspects of the conflict have tremendous importance, perhaps even more than purely military considerations. Appearing as murderous fanatics on world TV is probably the last thing you'd want to do in order to win the hearts of minds of the wider public. What may seem like a Hezbollah victory today, may be viewed very differently tomorrow. This reminds me of a Zen Master story mentioned in the movie "Charlie's War".

Do you know the story of Zen Master and the little boy?

There was a little boy. On his 14th birthday, he gets a horse. Everybody in the village says "how wonderful, the boy got a horse" and the Zen Master says "we'll see." Two years later the boy falls off the horse and breaks his leg. Everybody in the village says "how terrible" and the Zen master says "we'll see." Then, a war breaks out, and all the young men have to go and fight. The boy can't because his leg is all messed up. Everybody in the village says "how wonderful" and the Zen Master says...

Thursday, July 10, 2008

The iPhone this, the iPhone that

The new iPhone will be available for sale in Switzerland starting tomorrow. The local press is abuzz with the news. They claim that the iPhone is easy to use, the icons highly legible, the screen wider than the competition, its 3G technology allowing high-speed access to the internet. The iPhone this, the iPhone that.

But, no mention of Skype+iPhone integration. As a reminder, I carry around a telephone to transmit and receive sound, more precisely the sound of voice, mine and the person talking to me. Call and get called, without budgeting a second rent, is what I want from my phone. The ubiquitous Wi-Fi, plus Skype/iPhone combination would give me just that.

Unfortunately, it is not possible to run Skype over the iPhone. Sigh.

If you are looking for a start up idea, I've got one for you: build a phone based on Linux (or Windows), specifically designed to run Skype. I'd buy one, so would the rest of the planet.

Tuesday, July 08, 2008

Fighting spam with open-source tools

Being on many publicly accessible mailings lists exposes one's email address to spammers. So it happens that I receive a hefty amount of spam, i.e. 400 to 500 messages per day. Believe me when I say that pressing the "del" key for 15 minutes is not a good way to start a day.

Over the years I have tried several methods of varying complexity in order to cope with the scourge of spam.

We host our own email server. It uses Postfix. Postfix supports three strategies for filtering content. Initially, the "before queue, external" strategy seemed the most attractive to me. However, most of the examples on the web are based on the "after queue, external" strategy. So I decided to follow recipes found on the web for integrating SpamAssassin and postfix. Actually, the basic integration example found on the spamassassin wiki is an excellent start. Once you've got the basic version working, a simple variation thereof gives you the ability to quarantine messages. If you are not satisfied by just following recepies but would like to understand how the various pieces fit together, then you should read "Fighting Spam and SpamAssasin and Postfix".

Being essentially a rule engine, SpamAssassin can be integrated with other spam-fighting tools such as DCC and Razor. Given that we use Gentoo as our Linux distribution, for us this was easy as issuing the following two commands as root:
emerge mail-filter/razor
emerge mail-filter/dcc

I then had to change the following two lines in the /etc/spamassassin/local.cf file, from:
use_razor2  0
use_dcc 0
use_razor2  1
use_dcc 1
SpamAssassin assigns a score for each message it filters. SpamAssassin was configured to consider messages with scores 6.0 or above as spam. Such messages have their subject lines modified to contain "**** SPAM ****" as a prefix. SpamAssassin, or any spam-figting tool, may incorrectly identify a legitimate message as spam. Such occurrences are called false positives. They must be avoided, unless you don't mind loosing legitimate correspondence.

To reduce the probability of false positives, we adopted a two pronged strategy. Messages high spam scores, 9.0 and above, are quarantined in a special directory accessible only to the system administrator. They are not delivered to the mailbox of users. However, messages scoring "low", between 6.0 and 9.0, are still delivered to the user, with "**** SPAM ****" added to the subject line. With most email clients, e.g. Thunbderbird, it is rather easy to create a filtering rule which automatically moves messages with a subject line containing "**** SPAM ****" to a special SPAM folder. We thus give the user an opportunity to double check low-scoring spam messages before deleting them.

With this configuration and in the last 24 hours, SpamAssassin has quarantined 700 messages as spam (scores of 9.0 or above) for our whole site. My own various mailboxes received 50 low-scoring spam messages. Since such messages are filtered automatically, I am not distracted by them. Only 30 messages reached my mailbox in pristine form, of which 20 were legitimate and 10 were spam. This is such as huge improvement over the 20 spam to one legitimate message ratio we had previously.

For the next couple of weeks I will be looking at the high-scoring quarantined messages to check whether legitimate messages were mistakenly identified as spam (false positives). I am happy to report that there were no false positives in the 700 high-scoring messages nor in the 50 low-scoring messages.