how to protect from floods on port 80 (web)?
 

we're running a webserver and and we're experimenting this kind of problem... site is flooded and extremely slow.What can we do to protect the server from port 80 floods?
Thank you.

That's called a DoS and there's nothing really you can do about that except upgrading you bandwidth.
You could try increasing the amount of forks() your webserver is allowed to make, but I can't promise it'll work.

Are you not able to trace the IP? You could then just block the IP range from requesting any port on your server?

You can also try turning on tcp_syncookies and adjusting the network timeouts/buffers. But if it 's just a ton of of bandwidth being leveraged against you, iceman47's right in that there isn't much you can do. If that's the case, call your ISP and ask them to help you out. Usually they'll either work with you to filter stuff out farther upstream or they'll work with other ISPs to try and stop it at the source (if that's even possible).