C # socket UDP broadcast

First, broadcast News

Because TCP is connected, it cannot be used to send broadcast messages. To send a broadcast message, you must use UDP,UDP to send a message without establishing a connection. The destination IP address of a broadcast message is a special IP address, called a broadcast address. The broadcast address consists of an IP address network prefix plus a full 1 host suffix, such as: 192.168.1.255 is the broadcast address of the 192.169.1.0 network, and 130.168.255.255 is the broadcast address of the 130.168.0.0 network. If you send a message to all 1 IP addresses (255.255.255.255), then theoretically all networked computers in the world can be received. But this is not the case, the general router is set to abandon such a package, only in the local network broadcast, so the effect and to the local network broadcast address is the same as sending messages.

With UDP broadcasts you can implement a server like CS, and the client can receive a server message to connect.

Second, the service side

The open thread keeps broadcasting its own IP address, waiting for the client to receive

1 usingSystem;2 usingSystem.Collections.Generic;3 usingSystem.Linq;4 usingSystem.Text;5 usingSystem.Net;6 usingSystem.Net.Sockets;7 usingSystem.Threading;8 usingSystem.Threading.Tasks;9 Ten namespaceSCOKET_UDP_ Server One { A     class Program -     { -         Private StaticSocket sock; the         Private StaticIPEndPoint Iep1; -         Private Static byte[] data; -         Static voidMain (string[] args) -         { +Sock =Newsockets (AddressFamily.InterNetwork, Sockettype.dgram, - protocoltype.udp); +             //255.255.255.255 AIEP1 = at             NewIPEndPoint (Ipaddress.broadcast,9050); -  -             stringhostname =dns.gethostname (); -data =Encoding.ASCII.GetBytes (hostname); -  - sock. SetSocketOption (Socketoptionlevel.socket, inSocketoptionname.broadcast,1); -  toThread T =NewThread (broadcastmessage); + T.start (); -             //sock. Close (); the  * Console.readkey (); $ Panax Notoginseng         } -  the         Private Static voidbroadcastmessage () +         { A              while(true) the             { + sock. SendTo (data, IEP1); -Thread.Sleep ( -); $             } $              -         } -  the     } -}

Third, the client

1 usingSystem;2 usingSystem.Collections.Generic;3 usingSystem.Linq;4 usingSystem.Text;5 usingSystem.Net;6 usingSystem.Net.Sockets;7 usingSystem.Threading.Tasks;8 9 namespaceSocket Client UDPTen { One     class Program A     { -         Static voidMain (string[] args) -         { theSocket sock =NewSocket (AddressFamily.InterNetwork, - Sockettype.dgram, protocoltype.udp); -IPEndPoint IEP = -             NewIPEndPoint (Ipaddress.any,9050); + sock. Bind (IEP); -EndPoint EP =(EndPoint) IEP; +Console.WriteLine ("Ready to receive ..."); A  at             byte[] data =New byte[1024x768]; -             intrecv = sock. ReceiveFrom (data,refEP); -             stringStringData = Encoding.ASCII.GetString (data,0, recv); -  -Console.WriteLine ("received: {0} from: {1}", - StringData, Ep.           ToString ());  in sock. Close (); -  to Console.readkey (); +         } -     } the}

C # socket UDP broadcast