Sometimes I notice an abnormal amount of guests online, so I check the who's online list. When I check the who's online list I notice a lot of guests with the same IP address. Sometimes there can be upwards of 60 - 100 guests from the same ip address or sometimes even 200 - 500 guests.
On the who's online list they appear to be checking profiles, reading topics, searching, or viewing other parts of the board. I've tried banning the ip addresses, but they always come back under a different ip address.
I've also tried blocking bad bots with htaccess and blocking anything keyweb which does no good. When I did a whois on the ip address it appears to be coming from data centers in different locations for each different ip address.
I know it's not a search engine, as Google, Yahoo, and Msn don't hit websites en mass like this. I don't think it's a DDos attack either since my website experiences no downtime or hindered performance when these ip addresses hit my website en mass.
What is it and what can I do to stop it?