Nikolai, using a separate socket and bind(2) for each address or messing with routing tables is often not a feasible option e.g. with dynamic addresses. A single IP_ADDRANY-bound UDP server should be able to appear to respond on the same dynamically-assigned IP address a packet is received on. Luckily, there is another way. Depending on … Read more
This can happen if you filled up your socket buffer, but it is highly operating system dependent. Since UDP does not provide any guarantee your operating system can decide to do whatever it wants when your socket buffer is full: block or drop. You can try to increase SO_SNDBUF for temporary relief. This can even … Read more
TCP: Size of Ethernet frame – 24 Bytes Size of IPv4 Header (without any options) – 20 bytes Size of TCP Header (without any options) – 20 Bytes Total size of an Ethernet Frame carrying an IP Packet with an empty TCP Segment – 24 + 20 + 20 = 64 bytes UDP: Size of … Read more
When nc is listening to a UDP socket, it ‘locks on’ to the source port and source IP of the first packet it receives. Check out this trace: socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP) = 3 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 bind(3, {sa_family=AF_INET, sin_port=htons(10000), sin_addr=inet_addr(“127.0.0.1”)}, 16) = 0 recvfrom(3, “f\n”, 2048, MSG_PEEK, {sa_family=AF_INET, sin_port=htons(52832), sin_addr=inet_addr(“127.0.0.1”)}, [16]) … Read more
If you’re asking if you can use UDP as a Layer 2, then the answer is yes, sort of. There are various protocols that allow you to create a tunnel to another network using a UDP transport, such as L2TP and even IPsec (with NAT traversal). You could also do it at the application layer. … Read more
In many IP stack, such as Linux, this code does not work. Your socket must have broadcast permissions. Try this: bcast_sock = socket(AF_INET, SOCK_DGRAM, 0); int broadcastEnable=1; int ret=setsockopt(bcast_sock, SOL_SOCKET, SO_BROADCAST, &broadcastEnable, sizeof(broadcastEnable)); /* Add other code, sockaddr, sendto() etc. */
Unfortunately, there is no 100% reliable way to perform NAT hole punching with UDP. At best, you can make some guesses about how NATs and firewalls will probably behave most of the time. But there will always be exceptions and they may not be rare. In this case, it sounds like you are using a … Read more
It’s very simple to make same thing in C# Server: var Server = new UdpClient(8888); var ResponseData = Encoding.ASCII.GetBytes(“SomeResponseData”); while (true) { var ClientEp = new IPEndPoint(IPAddress.Any, 0); var ClientRequestData = Server.Receive(ref ClientEp); var ClientRequest = Encoding.ASCII.GetString(ClientRequestData); Console.WriteLine(“Recived {0} from {1}, sending response”, ClientRequest, ClientEp.Address.ToString()); Server.Send(ResponseData, ResponseData.Length, ClientEp); } Client: var Client = new UdpClient(); … Read more
Check live555 Useful libraries and code examples of how to stream stuff from your own app. The repo is full of RTP, RTSP, and SIP code examples and libraries.
As DJ pointed out, TCP is about getting a reliable data stream, and will slow down transmission, and re-transmit corrupted packets, in order to achieve that. UDP does not care about reliability of the communication, and will not slow down or re-transmit data. If your application needs a reliable data stream, for example, to retrieve … Read more