Sending a message to a local network in the broadcast style via UDP

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Sending a message to a local network in the broadcast style via UDP

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#1 by (3 votes)

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I made a question about P2P connection , then with one of the answers came the question: How to send a message on a local network via UDP in the broadcast style, without a specific recipient?

With this I would like the following solutions:

How do I find a potential recipient using UDP in the Broadcast style?
How to send messages via UDP?
What is the logic behind the "style" Broadcast and how it is done using UDP protocol.

If possible with an example in C #.

algoritmo c#

asked by anonymous 24.06.2015 / 23:06

1 answer

Select chained using only HTML and jQuery I can not check if an array is empty or null

score 3 · Accepted Answer

One way to understand how UDP works is by comparing it to TCP.

TCP

Connection : In order to use the TCP protocol, you need to establish a connection to a remote (and only) host.
Two-way communication : Once the connection is established, the two points can send messages (which is why IP tunneling works)
Peer : A connection involves only two points.
Guaranteed Transmission : Once a packet has been sent to a remote host, the protocol monitors the delivery (or warns you of faults).

UDP

Noconnection:YoudonotestablishconnectionswhenissuingUDPpackets;onlyspecifiesatarget.
Nowarranties:Theprotocoldoesnotimplementanykindofguaranteethatthepacketwillreachthedestinationhost.
Usingmasks:Apacketcanbesenttomultiplehostsatthesametimewhenthetargetisamask.

Intheexamplebelow,aUDPpacketsenttotheaddress192.168.1.255fromhost192.168.1.15willbereceivedbyallhostsofthesubnet,including192.168.1.15;Theoctet.255isequivalent,ingeneraltermsandinthegivenexample,to'allhostsunder192.168.1'.

UDP packet issue example (in C #):

static void SendUdp(int srcPort, string dstIp, int dstPort, byte[] data)
{
    using (UdpClient c = new UdpClient(srcPort))
        c.Send(data, data.Length, dstIp, dstPort);
}

SendUdp(11000, "192.168.1.255", 11000, Encoding.ASCII.GetBytes("Olá, eu sou o Goku!"));

The above example sends a UDP packet to all hosts on the current subnet and port 11000.