I am getting a lot of spam on a phpBB forum it's taking too much of my time to delete the spam. What can be done to lower the spam on the forum to prevent bots from registering and making crap posts for links?
For phpBB3 I would go to their download site and look at the CAPTCHA mods. Most spammers use bots for which phpBB3 is horribly vulnerable to. You should also upgrade phpBB3 to the latest and greatest which has better spam protection. We got so fed up with spending time on spam, that for the company I program for, we went to vBulletin and I spend very little time battling spammers.
You can do the normal stuff... captcha for registration (or even for posting new PMs/threads/posts if it's really bad). You can also spin incoming posts through https://akismet.com/ if you want. But if you *really* want to beat the spammers, you probably need to come up with a unique system that is unique to your site for doing it. Spammers aren't going to bother reverse engineering your methods just to get spam into a single site. But they will bother with coming up with common spam prevention methods that are used across a ton of sites (like captchas or Akismet filtering).
CAPTCHA works if you use something better than simple text images. You need CAPTCHA with background noise and images that are difficult for OCR scanners to pick up. If you really want to get out of battling spammers, I suggest investing in a license for vBulletin and go to that like we did. I do very little spammer killing now days.
If he's going to drop money on paid forum software to beat spammers, I think it should be IPB with their spam service. http://www.invisionpower.com/products/spammonitor/
The forum is simply an addition to my main site I definitely wouldn't consider forking out money for a vbulletin license just to beat spammers, at least not anyway.
vBulletin got hit pretty hard when reCAPTCHA got broken and the influx of spammers. IPB's Spam Service did a pretty good job, but I got hit for the first spam for the first time since I ever ran IPB 3. However, it wouldn't matter, cause my sig links are nofollow, I just reported him as a spammer, and banned him (and removed his sig). For phpBB, just use the Anti-Spam ACP MOD and use Question and Answer over any sort of CAPTCHA system. Also, have a lot of these question and answers ready as well.
And I find that it makes it more difficult for me to read as well these days. Another recommendation for vBulletin. Spammers at my sites are very few and far between; generally people sign up and leave a signature link at worst - they are set to nofollow so I don't see the harm.
I disagree. We moved to vBulletin and have no regrets and I use 4.0.8. I do agree that they change too much and fail to provide enough backward compatibility which results in some mods not working anymore, but overall they are way better than the alternatives. We used to use phpBB3, but problems there is existing bugs have went on for 4-5 years and never were fixed, some of them really serious too. That script is way too vulnerable to spamming and in some cases cross-site hacking depending on if you upgraded or not or configured your server to allow url includes on your websites.
SolveMedia is a good capture for phpBB, it also lets you earn from solved inputs. I find that writing a custom spam counter question upon registration really helps.