TcpListener Constructor (IPAddress, Int32)

Initializes a new instance of the TcpListener class that listens for incoming connection attempts on the specified local IP address and port number.

Namespace:  System.Net.Sockets
Assembly:  System (in System.dll)

public TcpListener(
	IPAddress localaddr,
	int port


Type: System.Net.IPAddress

An IPAddress that represents the local IP address.

Type: System.Int32

The port on which to listen for incoming connection attempts.


localaddr is null.


port is not between MinPort and MaxPort.

This constructor allows you to specify the local IP address and port number on which to listen for incoming connection attempts. Before calling this constructor you must first create an IPAddress using the desired local address. Pass this IPAddress to the constructor as the localaddr parameter. If you do not care which local address is assigned, specify IPAddress.Any for the localaddr parameter, and the underlying service provider will assign the most appropriate network address. This might help simplify your application if you have multiple network interfaces. If you do not care which local port is used, you can specify 0 for the port number. In this case, the service provider will assign an available port number between 1024 and 5000. If you use this approach, you can discover what local network address and port number has been assigned by using the LocalEndpoint property.

Call the Start method to begin listening for incoming connection attempts.


This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing in the .NET Framework.

The following code example creates an instance of the TcpListener class using a local IP address and port number.

    //Creates an instance of the TcpListener class by providing a local IP address and port number.

    IPAddress ipAddress = Dns.Resolve("localhost").AddressList[0];

        TcpListener tcpListener =  new TcpListener(ipAddress, 13);    
    catch ( Exception e){
        Console.WriteLine( e.ToString());

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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