Welcome to the world of the internet. Like has been stated, all this is just "noise". They have no target specifically, they are just looking for weak security to exploit. It does no good to try to block these as there are so many of them and a good number of these are spoofing perfectly good IP addresses so in some cases you would actually be doing yourself harm by blocking legitimate traffic.
The best thing you can do if you want to take the load off your server is to set up a good firewall not on your server but separately so that CPU cycles are not being used to deny access. I run pfsense boxes in front of all my servers and it's a wonderful setup. Even my Windoze admins can use the easy web GUI and I can still access the box via CLI if I want to.
Don't lose any sleep over these "attacks" as they aren't directed at you per se, and as long as they aren't getting in, you'll be fine.
-Tim
|