Get right ip adress of pc with multiple network cards

问题

Hej All, I've an application that listens on a socket. The problem is that the pc has 2 network cards and is connected to the company netork and a plc network of course we have to listen/bind/... onto the IPAdress we got from the DHCP in the company network.

But when we do this:

System.Net.IPEndPoint(System.Net.Dns.GetHostEntry(System.Net.Dns.GetHostName).AddressList(0)

We get the IP of the PLC network. Now we are looking for a way to find dynamically the right IPAdress. I got already the tip that you can bind a socket to the IPAdress (0:0:0:0) but we think it's a bit risky to do so.

Has anyone some ideas to solve this issue or some remarks about the 0:0:0:0?

Thanks in advance.

Jonathan

回答1:

The only risk in binding to 0.0.0.0, or leaving it as the default, is that you will accept connections via both networks. Only you know whether that is a risk, i.e. whether there are things in the other network that you don't want connecting to you. Binding to 0.0.0.0, aka INADDR_ANY, is the default and near-universal practice in network programming.

回答2:

Can't you loop through all adresses and use the one which is NOT 0.* and 168.* (or whatever the dhcp delivers...)

That should do in most(!) cases.

回答3:

I let the user decide to what networkinterface he/she wanted to connect to and placed that in an AppSetting. Then I create a module that reads the config file to decide what networkinterface to connect to, and to check and get the IPAddress I use this code

in vb.net:

 Dim networkinterfaces() As NetworkInterface = NetworkInterface.GetAllNetworkInterfaces()
            Dim found As Boolean = False

            For Each ni As NetworkInterface In networkinterfaces
                If NetworkInterfaceName.Equals(ni.Name) Then
                    If ni.GetPhysicalAddress().ToString().Length > 0 Then
                        IPAddressFromNetworkCard = ni.GetIPProperties.UnicastAddresses(0).Address
                        found = True
                        Exit For
                    End If
                End If
            Next

in c# (some more tracing, but it almost does the same):

Console.WriteLine("Test get ip of interfacecard");
            Console.WriteLine("Give name of interfacecard:");
            string s = Console.ReadLine();


            List<NetworkInterface> nics = NetworkInterface.GetAllNetworkInterfaces().ToList<NetworkInterface>();
            Console.WriteLine(nics.Count + "  networkinterfaces found");

            bool found = false;
            foreach (NetworkInterface ni in nics)
            {
                Console.WriteLine("Available nic: " + ni.Name);
            }
            Console.WriteLine("");
            Console.WriteLine(String.Format("searching for: \"{0}\"", s));
            foreach (NetworkInterface ni in nics)
            {
                if (ni.Name.Equals(s))
                {
                    if (ni.GetPhysicalAddress().ToString().Length > 0)
                    {
                        Console.WriteLine("Network interface found, ipAddress: " + ni.GetIPProperties().UnicastAddresses[0].Address.ToString());
                        found = true;
                        break;
                    }
                }

            }
            if (!found)
                Console.WriteLine(String.Format("\"{0}\" not found", s));

            Console.ReadKey();

来源：https://stackoverflow.com/questions/5143346/get-right-ip-adress-of-pc-with-multiple-network-cards

标签

sockets

networking

interface

hostname