[TheLastSuperman]

Originally Posted by elsa23

Thank you very much, that solve it

Session Timeout is set to 3600
but i have a "AhrefsBot" that is always connected with a multitude of activities, i don't know how to remove it
After i have resolved my session issue with your query, i have already 10 AhrefsBot in who is online and will increases every minute

That bot is said to follow the "rules" when it comes to being block-able via robots.txt:
http://help.ahrefs.com/about-ahrefs/...-via-robotstxt

So block it in that file, give it a little time then check. Malicious/Spambots typically do not follow the rules set forth in robots.txt / Only legitimate bots of constructive use follow the rules of robots.txt per say. If the bot is crawling your site though for some form of online search (such as Googlebots) then you should leave it active and allow it to crawl your site, crawlers are usually fine and do not cause harm and if you fixed the session timeout then the session table should not be filling up again anytime soon!