Hi Kelvin, I'm no expert in socket programing, I might be wrong ;) Yes you can create and bind both TCP and UDP sockets to the same port. Cos' TCP ports are independent of UDP ports. So you can just create a TCP socket; bind it and listen, follow by a UDP socket. A very good reference will be Unix Network Programming: Sockets and XTI by Richard Stevens. Page 233 ;) There is an example code on this. I think you can download the code on the net too. Don >>> "Kevin" <aotang@its.caltech.edu> 11/02/01 05:08PM >>> Hi, I want to listen the TCP connection and UDP connection on a single port. And use the select() to dectect the connection. I have two questions: 1. How can I build a socket for listening both of the two types of connection? 2. How can get to know it is a TCP connection or a UDP connection? - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html