My son wastes his free time playing online games, where he plays through the Internet with others.
That is too bad, at least he is being sociable and learning skills about computers by playing on them.
Yes, many online games have their own communities, but you never know who he is talking to.  I try to monitor as much as practical without being invasive.
That is true, there are a lot of dangerous people out there.  How old is he?
Online games have players of all ages, and thankfully my son just turned 17 so I hope he uses the scruples I gave him!  
I am sure he is and at 17 he has grown up with this technology so hopefully he understands how the predators work and he is careful on there!
I agree.  Some gamers are worried about gaming addiction, but he hasn't reached that point of awareness yet.  Hopefully that will come with maturity.
If he isn't addicted at 17 I am sure he is in the clear and like you said with maturity.