A simple equation challenge used as a Captcha


This plugin presents an anonymous user with simple math addition problems in order to submit a new ticket or to make edits in the wiki. Currently there is no customization: it presents two integers in the range of 1 - 10 and asks the user to add them together.

Version 2.0

I'm starting to see some particular spambots get through the simple captcha, so I'm releasing version 2.0 that includes a slight modification to the format presented to the user. In addition, this version now correctly works with fcgi and mod_python by saving the captcha information in the trac database. To use mod_python as an example: Apache may start many processes where each has its own embedded Python interpreter. The particular Apache process that displayed the form may not be the same one that processes the form request, so there must be a persistent way to store the solution to the captcha rather than making it easy for spambots by encoding the solution in the web page itself.

I'm also keeping a 30 day record of failed attempts in the same database so you can get an idea of what sort of spambots are trying to get through your defenses.

For the future, would be nice if there were multiple types of math problems presented in a way that wouldn't be easy for a bot to recognize.

Version 0.12

Thanks to user Srl295, the plugin now supports Trac 0.12. No database upgrade is necessary if migrating from 0.11.

Bugs/Feature Requests

Existing bugs and feature requests for MathCaptchaPlugin are here.

If you have any issues, create a new ticket.


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Download the zipped source from here.


You can check out MathCaptchaPlugin from here using Subversion, or browse the source with Trac.


Install by either copying the file into your /path/to/project/environment/plugins directory, or use the following from within the source directory:

python install

Version 2.0 of the plugin creates a new database needed for processing captchas when run using fcgi or mod_python, so you'll have to run the following before you can use the plugin:

trac-admin /path/to/project/environment upgrade

Once installed and the environment is upgraded, the plugin must be enabled by adding a line to the components section in your trac.ini file:

mathcaptcha.* = enabled

Finally, give anonymous users any of the following permissions:


Anonymous users will then be prompted to solve a math problem before being allowed to submit it, while authenticated users will not see the captcha.

Recent Changes

16419 by rjollos on 2017-03-29 19:53:47
5.0dev: Adapt to Trac 1.2 database API

Fixes #13131.

16418 by rjollos on 2017-03-29 17:56:36
5.0dev: Branch for Trac 1.2 and conform to PEP8

Refs #13131.

8267 by robm on 2010-07-15 15:27:49
Fixed #7155: added patches to support 0.12


Author: robm
Maintainer: Rob McMullen

Last modified 17 months ago Last modified on Nov 11, 2015, 10:08:25 AM