Nowadays, there is nearly no website providing any kind of input form for the user. But who provides one, opens a door for automatic bots producing spam and submitting those forms automatically i.e. to try to post website links as blog comments for forum entries.
To protect your website from this, captchas are a reasonable tool to protect from this. But even the spam bot developers have improved their software and bots are meanwhile able to read too simple captcha images. So it is necassary to make it difficult to interpretate the content of the captchaes for machines. Modifications such as including fractals in the images, rotating the letters and changing colors have been introduced.
However, using captchas always means to find the right balance between spam protection and providing usability to the website user who should still be able to interpretate the captcha content without getting nerved by the website.

To include captchas into your Typo3 website, the community has developed a range of extensions to generate and check such captchas. One of the established extensions is the Captcha Library developed by Kasper himself.

One of the major advantages of this extension is the configurability of the captcha generation. This enables you to configure the captcha complexity according to your website needs. Properties such as the risk of getting cracked by a spam bot and the required usability of your target website user group can be taken into account. The configuration of the captcha generation can be done through the extension manager by clicking on the extension itself, configuring the settings and update the configuration.

Over the last years we have evaluated different settings in our customer projects to find out which settings are working well for the majority of users. Unfortunately, the default settings are not the best in general.
The screenshot below shows the modified configuration we recommend to start with.

The settings are:
useTTF = true
imgWidth = 180
imgHeight = 50
captchaChars = 5
noNumbers = true
bold = false
noLower = false
noUpper = true
letterSpacing = 16
angle = 20
diffx = 0
diffy = 2
xpos = 3
ypos = 4
noises = 6
backcolor = #f4f4f4
textcolor = #000000
obfusccolor = #c0c0c0
fontSize = 20
excludeChars = gijloGIJLO0169

Depending on your website design you might also want to choose a specific font file using the setting

As mentioned before, for specific user groups and especially for websites with an increased risk such as shopping carts or similar, you should evaluate more complex settings.

Captcha in Typo3 Default Configuration

Post navigation

Leave a Reply