Blocking comment spam without using captcha [closed]

Solution 1:

In my experience the currently most effective methods are honeypot input fields that are made invisible to users via CSS (best use several different methods, such as visibility:hidden, setting a size of 0 pixels, and absolute positioning far outside the browser window); if they're filled anyway you can assume it's a spambot.

This blog describes a rather complex method that I've tried out myself (with 100% success so far), but I suspect that you could get the same result by skipping all the stuff with hashed field names and just add some simple honeypot fields.

Solution 2:

1) Adding session-related information into the form Example:

<input type="hidden" name="sh" value="<?php echo dechex(crc32(session_id())); ?>" />

then at postback, check whether session is valid or not.

2) Javascript-only. Use Javascript injection at Submission. Example:

<input type="hidden" id="txtKey" name="key" value="" />
<input type="submit" value="Go" onclick="document.getElementById('txtKey').value = '<?php echo dechex(crc32(session_id())) ?>';" />

3) Time-limit per IP, User or Session. this is quite straightforward.

4) Randomizing field names:

<?php
   $fieldkey = dechex(crc32(mt_rand().dechex(crc32(time()))));
   $_SESSION['fieldkey'] = $fieldkey;
?>
<input type="text" name="name<?php echo $fieldkey; ?>" value="" />
<input type="text" name="address<?php echo $fieldkey; ?>" value="" />

Then you can check it over at the server side.

Solution 3:

Akismet has an API. Someone wrote a wrapper class (BSD liscense) for it over at: http://cesars.users.phpclasses.org/browse/package/4401.html

There's also a Bayesian filter class (BSD Liscense as well) http://cesars.users.phpclasses.org/browse/package/4236.html

Blocking comment spam without using captcha [closed]

Solution 1:

Solution 2:

Solution 3:

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