Zbblock (system to protect PHP websites from SPAM and attacks, bots) may be outdated now, so check zbblock alternative CIDRAM:

https://cidram.github.io
https://github.com/CIDRAM/Docs/blob/master/readme.en.md (readme, installation steps)

If you know more alternatives, please let me know.

PS: another SPAM protection system is https://www.stopforumspam.com/mods