First, I'll be completely honest with you... if someone was scanning my computer and I found out that they had a backdoor, I'd have some fun with them. I would change a few things, play around, see if I could freshin my 'skills' (none what-so-ever) up a bit... but then afterwards I'd leave him a note somewhere explaining what's going on.. like "You have a backdoor on your PC." or something like that.
Jaguar: I think that what dopeydwarf is saying, is that the person that hes been getting scanned from has some backdoors open on his computer, and that someone might be using his computer to do the scans from.

At least I think thats what hes saying.