program CheckTCP_PortOpen;

{$APPTYPE CONSOLE}

uses
  Winsock; //Windows Sockets API Unit

    function PortTCPIsOpen(dwPort : Word; ipAddressStr:string) : boolean;
    var
      client : sockaddr_in;//sockaddr_in is used by Windows Sockets to specify a local or remote endpoint address
      sock   : Integer;
    begin
        client.sin_family      := AF_INET;
        client.sin_port        := htons(dwPort);//htons converts a u_short from host to TCP/IP network byte order.
        client.sin_addr.s_addr := inet_addr(PChar(ipAddressStr)); //the inet_addr function converts a string containing an IPv4 dotted-decimal address into a proper address for the IN_ADDR structure.
        sock  :=socket(AF_INET, SOCK_STREAM, 0);//The socket function creates a socket 
        Result:=connect(sock,client,SizeOf(client))=0;//establishes a connection to a specified socket.
    end;

var
  ret    : Integer;
  wsdata : WSAData;
begin
  Writeln('Init WinSock');
  ret := WSAStartup($0002, wsdata);//initiates use of the Winsock
  if ret<>0 then exit;
  try
    Writeln('Description : '+wsData.szDescription);
    Writeln('Status      : '+wsData.szSystemStatus);

    if PortTCPIsOpen(80,'127.0.0.1') then
    Writeln('Open')
    else
    Writeln('Close');

  finally
  WSACleanup; //terminates use of the Winsock
  end;

  Readln;
end.