Determine network status

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ComObj, ActiveX;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

uses ActiveDs_TLB;

{$R *.dfm}


procedure TForm1.Button1Click(Sender: TObject);
var
 wmi : variant;
 wmiService : variant;
 nicstatus : variant;
 card : Olevariant;
 cnt : integer;
 Enum: IEnumVariant;
 P : IUnknown;
 F : Cardinal;
 connected : integer;
 status : string;
begin
  WMI:=CreateOleObject('WbemScripting.SWbemLocator');
  wmiService := wmi.ConnectServer('.', 'root\wmi');
  nicstatus := wmiService.InstancesOf('MSNdis_MediaConnectStatus');
  p := nicstatus._NewEnum;
  p.QueryInterface(IEnumVariant, Enum);

  for cnt := 0 to nicstatus.Count - 1 do
   begin
     Enum.Next(1, card, F);
     connected := card.NdisMediaConnectStatus;
     if (connected = 0) then
       Status := 'connected'
        else
         Status := 'network cable unplugged';
     ShowMessage(card.InstanceName + ' : ' + Status);
   end;
end;


function IsNetworkAlive(flags : LPDWORD) : boolean; stdcall; external 'sensapi.dll';

procedure ShowNetworkStatus;
var
 Flags : DWORD;
 Res : boolean;
begin
  Res := IsNetworkAlive(@Flags);
  if Res then
   ShowMessage('Network connection is active')
    else
     ShowMessage('network cable unplugged');
end;

end.