Something really strange
 

i have in my forum always between 40~120 real guests with diffrences ips
but i dont know from where all came from they view my forum/posts some of them made an account and some of them posting advertise posts

any one have any idea how to check from where the guests linked to my site?

If your site is on the internet, it will be found.

im not talking on this, they are looks like a bots no one of them post a normal thread/post

What kind of spam protection do you have in place?

If you have cPanel as your server control panel you can look at "Awstats" and in "Connect to site from" you can see referers. On other control panels I have no idea.

They more than likely are bots. Try setting up some basic registration questions by going to AdminCP->Settings->Human Verification Manager. Some good questions that are simple for a user to answer will usually do the trick.