netfrag.org . TWiki . VisualConfirmPlugin
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VisualConfirmPlugin
Plugin for visual confirmation of new user registration, to prevent automated scripts to create users and spam your wiki with their url's to get a better google ranking.
Syntax Rules
Examples
Plugin Settings
Plugin settings are stored as preferences variables. To reference a plugin setting write %<plugin>_<setting>%
, i.e. %INTERWIKIPLUGIN_SHORTDESCRIPTION%
- One line description, is shown in the TextFormattingRules topic:
- Set SHORTDESCRIPTION = Plugin for visual confirmation of new user registration.
- Debug plugin: (See output in
data/debug.txt
)
- Custom settings (defaults shown):
- Characters to use in generated strings:
- Set CHARACTERS = ABCDEFGHKLMNPRSTVWXYZabcdeghpqsuvwxy@
- Truetype font to use:
- Number of random lines to add (use
none
for 0):
- Number of random circles to add (use
none
for 0):
- Noise, percentage of pixels to flip randomly after generating graphics (use
none
for 0%):
Plugin Installation Instructions
Note: You do not need to install anything on the browser to use this plugin. The following instructions are for the administrator who installs the plugin on the server where TWiki is running.
- Download the ZIP file from the Plugin web (see below)
- Unzip
VisualConfirmPlugin.zip
in your twiki installation directory. Content:
File: | Description: |
data/TWiki/VisualConfirmPlugin.txt | Plugin topic |
data/TWiki/VisualConfirmPlugin.txt,v | Plugin topic repository |
register.patch | Patch for the register binary |
templates/oopsregvisualconfirm.tmpl | Error template |
lib/TWiki/Plugins/VisualConfirmPlugin.pm | Plugin Perl module |
- Apply the patch
register.patch
to bin/register
(alternatively, patch register manual, see section below):
- cd bin
- patch < ../register.patch
- Create the directories
visualconfirm
and visualconfirm/db
in your pub/
directory, and make sure it is readable and writable by the user that TWiki is executing as.
- mkdir -p pub/visualconfirm/db
- chown -R nobody pub/visualconfirm
- chmod -R 644 pub/visualconfirm
- Restrict access to the database files, for example, by including the following in your httpd.conf:
<Directory "/path/to/twiki/pub/visualconfirm/db">
deny from all
</Directory>
- Make sure the plugin has access to the preferred truetype font, by putting the
.ttf
file in pub/visualconfirm/
- Test if the installation was successful:
- Create a topic containing
<IMG SRC="%VISUALCONFIRMURL%">
and %VISUALCONFIRMHASH%
- When loading this topic you should see an obfuscated character string loaded as a png and a hexadecimal hash.
- Check whether the hash database is properly protected by going to the url http://my.twiki.server/my/twiki/path/pub/visualconfirm/db/hashes.pag, you should see a permission denied message.
- Now edit your TWikiRegistration topic
- Display the image %VISUALCONFIRMURL% somewhere in your form, along with a text instructing new users to copy the obfuscated text into the appropriate text input.
- Add the appropriate text input as
Twk1VisualConfirm
- Add a hidden input as
Twk1VisualConfirmHash
- For example, add this to your TWikiRegistration:
<tr>
<td valign="top" align="right"><IMG SRC="%VISUALCONFIRMURL%">: <br /> (..) </td>
<td><input type="hidden" name="Twk1VisualConfirmHash" value="%VISUALCONFIRMHASH%">
<input type="text" name="Twk1VisualConfirm" size="5"></td>
</tr>
Manually patching the register binary
Find the line in bin/register
that says:
# everything OK
Insert the code below directly BEFORE that line:
# check valid visual confirmation
for( $x = 0; $x < $formLen; $x++ ) {
$vcHash=$formDataValue[$x]
unless(not($formDataName[$x] eq "Visual Confirm Hash"));
$vcTxt=$formDataValue[$x]
unless(not($formDataName[$x] eq "Visual Confirm"));
}
open(LOCKFILE,">".&TWiki::getPubDir()."/visualconfirm/db/hashes.lock");
flock(LOCKFILE,2);
dbmopen(%database, &TWiki::getPubDir()."/visualconfirm/db/hashes" ,0644);
if(!defined($database{$vcHash})) {
$url = &TWiki::getOopsUrl( $webName, $topic, "oopsregvisualconfirm",
"The visual confirmation has expired.");
TWiki::redirect( $query, $url );
return;
}
my ($time,$txt)=split(',',$database{$vcHash});
if(not(lc($txt) eq lc($vcTxt))) {
$url = &TWiki::getOopsUrl( $webName, $topic, "oopsregvisualconfirm",
"The character string you entered for visual confirmation is incorrect.");
TWiki::redirect( $query, $url );
return;
}
dbmclose(%database);
close(LOCKFILE);
Further Development
- Make number of characters configurable
- Make font size configurable
- Find out how to safely delete images from the register binary
Plugin Info
Related Topics: TWikiPreferences, TWikiPlugins
-- TWiki:Main.KoenMartens - 07 Oct 2005
----- Revision r1.4 - 10 Oct 2005 - 17:16 - KoenMartens?
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