phpBB3 has a few options to stop spammy bots. The default captcha generated images are not enough.
One of the captcha option is called “Q&A” (“Question and answer”).
Q&A is an already installed plugin that comes with the default phpBB3. Follow these steps in order to configure it:
Configuring Q&A for phpBB3
- login into the admin panel
- from “general”, access “Spambot countermeasures”.
- go to “Installed plugins” > select “Q&A” (it should be gray).
- access the “configure” button > “add your antispam question”, here is an example: “5+5=? (numeric) (antispam question)”. The users that will try to register should have to write “10″ in order to pass the anti-spam test.
- go back to “Spambot countermeasures”, Q&A should be turned black (from gray), and already available for new users that are looking to register.