First thanks, Oleg Moskalenko for your reply.I solved my problem. thank you.
Then, I have one more question.I want to group peers and allow to communicate among peers in same group.But i don't know how to config turn server.my main question is these1. Does turn server have a functionality to group peers?
2.If it does, how can i config server?
3. if it does not, what alternative do i have?
Thanks Oleg!!!