multicast

问题 Referring to the Java 6 API docs for the DatagramSocket class: UDP broadcasts sends are always enabled on a DatagramSocket. In order to receive broadcast packets a DatagramSocket should be bound to the wildcard address . In some implementations, broadcast packets may also be received when a DatagramSocket is bound to a more specific address. Could someone tell me what the 'wildcard address' is? And is the following valid for listening for UDP broadcasts: MulticastSocket socket = new

问题 I'm using GCDAsyncUdpSocket and i can send either Multicast or normal UDP packets. I'm receiving normal packets with no problem but I cant receive Multicast packets from another iOS device. To receive I use: - (void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data fromAddress: (NSData *)address withFilterContext:(id)filterContext { NSString *msg = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease]; NSString *host = nil; uint16_t port = 0;

问题 I'm using GCDAsyncUdpSocket and i can send either Multicast or normal UDP packets. I'm receiving normal packets with no problem but I cant receive Multicast packets from another iOS device. To receive I use: - (void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data fromAddress: (NSData *)address withFilterContext:(id)filterContext { NSString *msg = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease]; NSString *host = nil; uint16_t port = 0;

问题 I'm using multicast UDP over localhost to implement a loose collection of cooperative programs running on a single machine. The following code works well on Mac OSX, Windows and linux. The flaw is that the code will receive UDP packets outside of the localhost network as well. For example, sendSock.sendto(pkt, ('192.168.0.25', 1600)) is received by my test machine when sent from another box on my network. import platform, time, socket, select addr = ("239.255.2.9", 1600) sendSock = socket

问题 I was trying to write a simple program communicating between kernel and user space using Netlink. Basically here's what I wanted to achieve: User space program starts binding to a user defined multicast group. Insert kernel module Kernel module sends a message to this multicast group User space program receives the message Here's my code: ======User space program====== #include<stdio.h> #include<string.h> #include<stdlib.h> #include<sys/socket.h> #include<linux/netlink.h> #include<sys/types.h

问题 I have multiple processes sending different types of messages to the same ip and port so that when I write the client I would only need one reader thread rather than multiple reader threads. Have I embarked on a design pattern or is my strategy ill advised? Obviously, I could send to different ip:port but that would mean multiple threads on my client. Any thoughts? 回答1: You send multicast data to a group and port, not to "host". Listening processes would have to join that group, and sending

问题 I'm trying to send a multicast to all network computers. I have my server set up on my computer and another computer on the network. When I send out the multicast message, the server running on my computer picks it up fine. The networked computer doesn't get anything though. I've tried setting the TTL to its max value and that hasn't done anything. I've also tried monitoring my packets using WireShark, but didn't see anything (I'm not very skilled with this). I'm confused why my computer

问题 I'm having a problem getting UDP multicast send to work from Windows 8.1. The following simple test program works from within an interface-bridged VM running Windows 7 or Ubuntu 13 on the same host. For this reason I am sure that the issue is not with the java test program, or with the physical network configuration. import java.net.*; public class multicast_send { public static void main(String[] args) throws Exception { DatagramSocket socket = null; DatagramPacket outPacket = null; socket =

问题 I have a TCP based Netty application with multiple clients that need to communicate with each other. I store all of the Channel references in a ChannelGroup. While I know that I can write to every client in a ChannelGroup by calling ChannelGroup.write, but what would be an efficient way to write to all but one of these channels, for example: 'A','B','C' are in a Channel Group together and 'A' needs to send to 'B' and 'C', 'B' needs to send to 'A' and 'C', etc. What would be the best way to do

问题 I have a Windows machine where I have two scripts that send and receive messages via UDP multicast (on the same machine). I have a C and Python3 implementation of this. The Python3 one looks like this: sender.py import socket MCAST_GRP = '239.1.1.1' MCAST_PORT = 1234 sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP) sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 2) print("Sending") sock.sendto(bytearray("str()", "utf-8"), (MCAST_GRP, MCAST_PORT)) data,