Archive for category Spam protection

Avoid becoming a spam source

The number one rule in programming is not to trust external data, especially not user data. One of the reasons not to trust user data is the threat of hackers searching for injection possibilities. When you start develloping web applications you’ll soon learn the dangers of SQL injection. This might be the most important form of injection, but by far it is not the only one out there: cross site scripting is another good example. If your application sends out mail, you might want to make sure you sanitize user input as well as the application could be a magnet for spammers who’ll send spam mail using your IP. Read the rest of this entry »

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No robots beyond this line

Customs passport checkOnline communities are hot. Globally recognized examples are easy to give: websites like Facebook, LinkedIn and are very popular, manufacturers have online fora to have their customers support each other, newspapers let you leave comments on their articles on their websites and you can share everything with tools like Delicious, Digg and Reddit. This development on the Internet supports new possibilities which were unknown before. Of course this also counts for rogues. Spam is a commonly known phenomenon and global annoyance. Beside spamming unwanted messages by mail, spamming the comment boxes and fora is an issue web programmers have to deal with too. Spamming often is automated and this is a feature which can be used to counter spam. The goal is to identify a messenger being human or robot.

For this purpose the captcha was invented. Besides the fact that captcha sounds nice enough to be a buzz word it actually is short for Completely Automated Public Turing test to tell Computers and Humans Apart, although this is a bit contrived. This means that a captcha is a challenge response mechanism but it doesn’t need to be in the form of an image depicting distorted text which has to be copied in a text box which is the most common form of captchas. Creative new captchas can be found, like a transistor image which has to be read. Read the rest of this entry »

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