In my case db is on local lan, with a firewall filtering incoming requests. Of course hackers are just round the corner, so everybody must take his own countermeasures to void this. I think that a publicly accessible DB engine is always weak. Using different port than the default(like I do with Remote Desktop on my hosted servers, which is bombed by hackers at least 3000 times a day), confuses them. They know something il listening, but what is it?