[Mono-dev] mutilcast group membership doesn't work

Gladish, Jacob Jacob.Gladish at sig.com
Fri Mar 13 10:43:53 EDT 2009

Nothing appears to be returned from a call to  NetworkInterface.GetIPProperties().MulticastAddresses, when I'm joined to one or more multicast groups.  I confirmed that on Windows using MS.NET that it indeed returns all multicast joins for each interface.

The mono framework appears to be using getifaddrs(3). I don't know whether that's supposed to return multicast info or not. I ran a small test on Linux calling it directly. No multicast addresses where returned. I wanted to confirm this behavior with someone else before filing a bug.

If you run strace on netstat you'll see that it reads /proc/net/igmp.

using System;
using System.Net.NetworkInformation;

namespace McastInfo
    class Program
        static void Main(string[] args) {
            foreach (NetworkInterface nic in NetworkInterface.GetAllNetworkInterfaces()) {
                Console.WriteLine("interface: {0}", nic.Description);
                foreach (MulticastIPAddressInformation mcastInfo in nic.GetIPProperties().MulticastAddresses) {
                    Console.WriteLine("mcast-addr: {0}", mcastInfo.Address);

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