multicast

Here's what I'm trying to do- A server sends out "Alive message to all the PCs on the network and the PCs which are up and running, respond to the call by sending their IP. I'm looking at a lightweight piece of coding as this will form a small bit of my application. I've looked at Jini and other services but find that I may not need even half of their features(except for the network discovery) Is it ok if I: 1. Use a for loop where a server opens a socket, checks(using a for loop) if all the IPs x.x.x.x are reachable by sending an "Alive" message. 2. On receiving the "alive" message at the

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.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP) sendSock.setsockopt(socket.IPPROTO_IP,

I need to determine the IP of a machine that has sent me a multicast packet, so that I can respond to it via unicast. I'm using the following csharp (.Net 3.5) code to receive the packets over a multicast connection (code has been edited for brevity, with error checking and irrelevant options removed): IPEndPoint LocalHostIPEnd = new IPEndPoint(IPAddress.Any, 8623); Socket UDPSocket = new Socket(AddressFamily.InterNetwork,SocketType.Dgram,ProtocolType.Udp); UDPSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastLoopback, 1); UDPSocket.Bind(LocalHostIPEnd); //Join the

I was trying to reproduce the example from a previous SO post on a kernel above 4 (4.1): #include <linux/module.h> #include <linux/kernel.h> #include <linux/netlink.h> #include <net/netlink.h> #include <net/net_namespace.h> /* Protocol family, consistent in both kernel prog and user prog. */ #define MYPROTO NETLINK_USERSOCK /* Multicast group, consistent in both kernel prog and user prog. */ #define MYGRP 31 static struct sock *nl_sk = NULL; static void send_to_user(void) { struct sk_buff *skb; struct nlmsghdr *nlh; char *msg = "Hello from kernel"; int msg_size = strlen(msg) + 1; int res; pr

I'm writing a UDP multicast client/server pair in C# and I need a delay on the order of 50-100 µsec (microseconds) to throttle the server transmission rate. This helps to avoid significant packet loss and also helps to keep from overloading the clients that are disk I/O bound. Please do not suggest Thread.Sleep or Thread.SpinWait. I would not ask if I needed either of those. My first thought was to use some kind of a high-performance counter and do a simple while() loop checking the elapsed time but I'd like to avoid that as it feels kludgey. Wouldn't that also peg the CPU utilization for the