AddressFamily Enumeration

AddressFamily Enumeration

Specifies the addressing scheme that an instance of the Socket class can use.

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

public enum AddressFamily

Member nameDescription
UnknownUnknown address family.
UnspecifiedUnspecified address family.
UnixUnix local to host address.
InterNetworkAddress for IP version 4.
ImpLinkARPANET IMP address.
PupAddress for PUP protocols.
ChaosAddress for MIT CHAOS protocols.
NSAddress for Xerox NS protocols.
IpxIPX or SPX address.
IsoAddress for ISO protocols.
OsiAddress for OSI protocols.
EcmaEuropean Computer Manufacturers Association (ECMA) address.
DataKitAddress for Datakit protocols.
CcittAddresses for CCITT protocols, such as X.25.
SnaIBM SNA address.
DecNetDECnet address.
DataLinkDirect data-link interface address.
LatLAT address.
HyperChannelNSC Hyperchannel address.
AppleTalkAppleTalk address.
NetBiosNetBios address.
VoiceViewVoiceView address.
FireFoxFireFox address.
BanyanBanyan address.
AtmNative ATM services address.
InterNetworkV6Address for IP version 6.
ClusterAddress for Microsoft cluster products.
Ieee12844IEEE 1284.4 workgroup address.
IrdaIrDA address.
NetworkDesignersAddress for Network Designers OSI gateway-enabled protocols.
MaxMAX address.

An AddressFamily member specifies the addressing scheme that a Socket will use to resolve an address. For example, InterNetwork indicates that an IP version 4 address is expected when a Socket connects to an endpoint.

The following example creates a Socket using the InterNetwork AddressFamily.

using System;
using System.Text;
using System.IO;
using System.Net;
using System.Net.Sockets;

public class Sample

  public static string DoSocketGet(string server) 
    //Set up variables and String to write to the server.
    Encoding ASCII = Encoding.ASCII;
    string Get = "GET / HTTP/1.1\r\nHost: " + server + 
                 "\r\nConnection: Close\r\n\r\n";
    Byte[] ByteGet = ASCII.GetBytes(Get);
    Byte[] RecvBytes = new Byte[256];
    String strRetPage = null;

    // IPAddress and IPEndPoint represent the endpoint that will
    //   receive the request.
    // Get first IPAddress in list return by DNS.


      // Define those variables to be evaluated in the next for loop and 
      // then used to connect to the server. These variables are defined
      // outside the for loop to make them accessible there after.
      Socket s = null;
      IPEndPoint hostEndPoint;
      IPAddress hostAddress = null;
      int conPort = 80;

      // Get DNS host information.
      IPHostEntry hostInfo = Dns.GetHostEntry(server);
      // Get the DNS IP addresses associated with the host.
      IPAddress[] IPaddresses = hostInfo.AddressList;

      // Evaluate the socket and receiving host IPAddress and IPEndPoint. 
      for (int index=0; index<IPaddresses.Length; index++)
        hostAddress = IPaddresses[index];
        hostEndPoint = new IPEndPoint(hostAddress, conPort);

        // Creates the Socket to send data over a TCP connection.
        s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp );

        // Connect to the host using its IPEndPoint.

        if (!s.Connected)
          // Connection failed, try next IPaddress.
          strRetPage = "Unable to connect to host";
          s = null;

        // Sent the GET request to the host.
        s.Send(ByteGet, ByteGet.Length, 0);

      } // End of the for loop.      

      // Receive the host home page content and loop until all the data is received.
      Int32 bytes = s.Receive(RecvBytes, RecvBytes.Length, 0);
      strRetPage = "Default HTML page on " + server + ":\r\n";
      strRetPage = strRetPage + ASCII.GetString(RecvBytes, 0, bytes);

      while (bytes > 0)
        bytes = s.Receive(RecvBytes, RecvBytes.Length, 0);
        strRetPage = strRetPage + ASCII.GetString(RecvBytes, 0, bytes);

    } // End of the try block.

    catch(SocketException e) 
      Console.WriteLine("SocketException caught!!!");
      Console.WriteLine("Source : " + e.Source);
      Console.WriteLine("Message : " + e.Message);
    catch(ArgumentNullException e)
      Console.WriteLine("ArgumentNullException caught!!!");
      Console.WriteLine("Source : " + e.Source);
      Console.WriteLine("Message : " + e.Message);
    catch(NullReferenceException e)
      Console.WriteLine("NullReferenceException caught!!!");
      Console.WriteLine("Source : " + e.Source);
      Console.WriteLine("Message : " + e.Message);
    catch(Exception e)
      Console.WriteLine("Exception caught!!!");
      Console.WriteLine("Source : " + e.Source);
      Console.WriteLine("Message : " + e.Message);

    return strRetPage;

   public static void Main()

.NET Framework

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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