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c# Ping a TCP Client from the server

How can a TcpClient be pinged from a server in order to see its response time? I have a TCPServer that I have created with a TCPClientManager that I have also created. This simply adds a new Client with a .NET TcpClient property to aList whenever a client connects. How can I get the address of the TcpClient so that I can ping it using .NET Ping ?
public long PingClient(Client client)
{
long pingTime = 0;
Ping pingSender = new Ping();
// The class Client has a property tcpClient of type TcpClient
IPAddress address = IPAddress.Parse(Client.tcpClient...???);
PingReply reply = pingSender.Send(address);
if (reply.Status == IPStatus.Success)
{
pingTime = reply.RoundtripTime;
}
return pingTime;
}

If I understood your question correctly you want the IPAddress of the connected TcpClient which can be accomplished by accessing the underlaying socket (which is exposed through the Client property) and using it's EndPoint property.
You will have to cast it to an IPEndPoint in order to access it correctly.
In your case just use ((IPEndPoint)client.Client.RemoteEndPoint).Address which will return an IPAddress.
So you would have to change your example from:
IPAddress address = IPAddress.Parse(Client.tcpClient...???);
to:
IPAddress address = ((IPEndPoint)client.Client.RemoteEndPoint).Address;

C# Get IP assigned by router

I don't know if I'm just not searching using the right keywords, I want to be able to find the IP address of my local computer that was assigned by my router.
I was using:
IPHostEntry host;
host = Dns.GetHostEntry(Dns.GetHostName());
foreach(IPAddress ip in host.AddressList)
{
if(ip.addressfamily.tostring() == "InterNetwork")
{
return ip;
}
}
The problem is I have multiple InterNetwork ip addresses because I use virtual services, so I need to be able to identify which one was assigned by my router.

How about loopback?
if (IPAddress.IsLoopback(ip)) return ip; //localhost
Or try pinging the local machine
Ping pingSender = new Ping ();
IPAddress address = IPAddress.Loopback;
PingReply reply = pingSender.Send (address);
if (reply.Status == IPStatus.Success){..}
also this might help you
Showing The External IP-Address In C#

IP routing table lookup in .net

I have a multi-homed machine and need to answer this question:
Given an IP address of the remote machine, which local interface is appropriate to use for communication.
This needs to be done in C#. I can do this query using Win32 Socket and SIO_ROUTING_INTERFACE_QUERY but looking around in the .net framework documentation I haven't found an equivalent for it.

Someone was nice enough to writez the code, see https://searchcode.com/codesearch/view/7464800/
private static IPEndPoint QueryRoutingInterface(
Socket socket,
IPEndPoint remoteEndPoint)
{
SocketAddress address = remoteEndPoint.Serialize();
byte[] remoteAddrBytes = new byte[address.Size];
for (int i = 0; i < address.Size; i++) {
remoteAddrBytes[i] = address[i];
}
byte[] outBytes = new byte[remoteAddrBytes.Length];
socket.IOControl(
IOControlCode.RoutingInterfaceQuery,
remoteAddrBytes,
outBytes);
for (int i = 0; i < address.Size; i++) {
address[i] = outBytes[i];
}
EndPoint ep = remoteEndPoint.Create(address);
return (IPEndPoint)ep;
}
which is used like (example!):
IPAddress remoteIp = IPAddress.Parse("192.168.1.55");
IpEndPoint remoteEndPoint = new IPEndPoint(remoteIp, 0);
Socket socket = new Socket(
AddressFamily.InterNetwork,
SocketType.Dgram,
ProtocolType.Udp);
IPEndPoint localEndPoint = QueryRoutingInterface(socket, remoteEndPoint );
Console.WriteLine("Local EndPoint is: {0}", localEndPoint);
Please note that although one is specifying an IpEndPoint with a Port, the port is irrelevant. Also, the returned IpEndPoint.Port is always 0.

I didn't know about this, so just had a look in the Visual Studio Object browser, and it looks like you can do this from the System.Net.Sockets namespace.
In that namespace is a Socket class which contains a method IOControl. One of the overloads for this method takes an IOControlCode (enum in the same namespace) which contains an entry for `RoutingInterfaceQuery'.
I'll try and put some code together as an example now.

Resolve HostName to IP

I have been through a lot of googling for this, I found a lot of examples none of which was working for me. This is a simple issue which I feel has a simple answer without defining new classes\modules etc...
My code is this :
Console.WriteLine ("Please enter an IP address or hostname");
string host = Console.ReadLine ();
***IP = resolved "host"***
Socket s = new Socket (AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
s.Connect (IP, 80);
s.close();
How do I actually resolve the IP variable?

You can simply use the DNS class to do so:
IPHostEntry hostEntry;
hostEntry= Dns.GetHostEntry(host);
//you might get more than one ip for a hostname since
//DNS supports more than one record
if (hostEntry.AddressList.Length > 0)
{
var ip = hostEntry.AddressList[0];
Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
s.Connect(ip, 80);
}

string howtogeek = "www.howtogeek.com";
IPAddress[] addresslist = Dns.GetHostAddresses(howtogeek);
foreach (IPAddress theaddress in addresslist)
{
Console.WriteLine(theaddress.ToString());
}
from howtogeek

Please take the note that accepted answer can resolve to IPv6. I attempted to connect to service that does not accept IPv6 as input string.
Therefore try this snippet if you care to get IPv4:
using System.Linq;
string host = "google.com";
Dns.GetHostEntry(host).AddressList.First(addr => addr.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)

This is the method I use to resolve a hostname to IPv4 and / or IPv6.
using System.Net:
// A host can have multiple IP addresses!
public static IPAddress[] GetIPsByName(string hostName, bool ip4Wanted, bool ip6Wanted)
{
// Check if the hostname is already an IPAddress
IPAddress outIpAddress;
if (IPAddress.TryParse(hostName, out outIpAddress) == true)
return new IPAddress[] { outIpAddress };
//<----------
IPAddress[] addresslist = Dns.GetHostAddresses(hostName);
if (addresslist == null || addresslist.Length == 0)
return new IPAddress[0];
//<----------
if (ip4Wanted && ip6Wanted)
return addresslist;
//<----------
if (ip4Wanted)
return addresslist.Where(o => o.AddressFamily == AddressFamily.InterNetwork).ToArray();
//<----------
if (ip6Wanted)
return addresslist.Where(o => o.AddressFamily == AddressFamily.InterNetworkV6).ToArray();
//<----------
return new IPAddress[0];
}

If all you want is to resolve a string that could represent either a hostname OR an IP address, you probably want to use System.Net.Dns.GetHostAddresses() rather than System.Net.Dns.GetHostEntry().
GetHostAddresses() skips the DNS lookup if the string parses to an IP address already, while GetHostEntry() will do a reverse lookup for the hostname.
https://learn.microsoft.com/en-us/dotnet/api/system.net.dns.gethostaddresses

The IpAddress has the appropriate method for parsing hostname to IpAddress.
IPAddress addr = IPAddress.Parse(hostName)

TCP Debug Error C#

public Server([Optional, DefaultParameterValue(0x6c1)] int port, [Optional, DefaultParameterValue("127.0.0.1")] string ip)
{
this.IP = IPAddress.Parse(ip);
this.Port = port;
this.listenerConnection = new TcpListener(this.IP, this.Port);
this.listenerConnection.Start();
this.listenerThread = new Thread(new ThreadStart(this.listen));
this.listenerThread.Start();
}
is the code I have, it runs fine but when I debug it, I get the message:
Specified argument was out of the range of valid values. Parameter name: port
Can anyone help?

Well, then port is out of the range of valid values, which is between IPEndPoint.MinPort and IPEndPoint.MaxPort.

Have you tried using the IPAddress of your machine? You can use the following code to obtain the IPAddress of the machine you are running the application on:
IPHostEntry host = Dns.GetHostEntry(Dns.GetHostName());
IPAddress localIpAddress = null;
forach(IPAddress address in host.AddressList)
{
if(address.AddressFamily == AddressFamily.InterNetwork)
{
localIpAddress = address;
}
}
TcpListener listener = new TcpListener(localIpAddress, port);
listener.Start();
Additionally, you may want to consider using a default port > 5000. As there are many ports between 0 and 5000 that are reserved or already use by services.