在局域网里如何确认一个IP是否已经连接网络

Question

如何通过DELPHI编程的方式确认局域网里的一个IP是否已经连接网络

Answer 1

用PING的方法会被防火墙给挡住,无法真实的反应情况,除了PING之外还有其他方法吗

Answer 2

只要你用网络发包，就有可能被防火墙挡住。所以即使有除了ping之外的其他方法，也满足不了你的要求~！

Answer 3

那像网络执法管那样的软件就能在防火墙开启的情况下,依然可以探测到主机的网络状态
---------------------我没有用过网络执法官这样的软件, 但, 估计, 它是要在每台机器上安装一个Server端或Client端的. 也就是说, 给防火墙开了后门.

Answer 4

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls, StdCtrls,Registry,WinInet;type
  TForm1 = class(TForm)
    Timer1: TTimer;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Edit1: TEdit;
    Memo1: TMemo;
    procedure Button2Click(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;
implementation{$R *.dfm}
function CheckOffline: boolean;
var
  ConnectState: DWORD;
  StateSize: DWORD;
begin
  ConnectState:= 0;
  StateSize:= SizeOf(ConnectState);
  result:= false;
  if InternetQueryOption(nil, INTERNET_OPTION_CONNECTED_STATE, @ConnectState, StateSize) then
  if (ConnectState and INTERNET_STATE_DISCONNECTED) <> 2 then result:= true;
end;procedure TForm1.Button2Click(Sender: TObject);
var
 b: array[0..4] of Byte;
begin
  with TRegistry.Create do
        try
           RootKey := HKEY_LOCAL_MACHINE;
           OpenKey('System\CurrentControlSet\Services\RemoteAccess',False);
           ReadBinaryData('Remote Connection',b,4);
        finally
           Free;
        end;
 if b[0]=1 then Caption:='在线' else Caption:='离线';
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
 if InternetCheckConnection('http://mail.163.com/', 1, 0) then Caption:= 'Connected'   else  Caption:= 'Disconnected';
end;procedure TForm1.Button3Click(Sender: TObject);
begin
  if CheckOffline then  Caption:='在线' else Caption:='离线';
end;end.

Answer 5

我收集了个公共函数,贴上来,需要添加winsock单元引用(也是逃不过防火墙)
Function CheckNet(IpAddr: string): Boolean;
type
  PIPOptionInformation = ^TIPOptionInformation;
  TIPOptionInformation = packed record
     TTL:         Byte;      // Time To Live (used for traceroute)
     TOS:         Byte;      // Type Of Service (usually 0)
     Flags:       Byte;      // IP header flags (usually 0)
     OptionsSize: Byte;      // Size of options data (usually 0, max 40)
     OptionsData: PChar;     // Options data buffer
  end;  PIcmpEchoReply = ^TIcmpEchoReply;
  TIcmpEchoReply = packed record
     Address:       DWord;                // replying address
     Status:        DWord;                // IP status value (see below)
     RTT:           DWord;                // Round Trip Time in milliseconds
     DataSize:      Word;                 // reply data size
     Reserved:      Word;
     Data:          Pointer;              // pointer to reply data buffer
     Options:       TIPOptionInformation; // reply options
  end;  TIcmpCreateFile = function: THandle; stdcall;
  TIcmpCloseHandle = function(IcmpHandle: THandle): Boolean; stdcall;
  TIcmpSendEcho = function(
     IcmpHandle:          THandle;
     DestinationAddress:  DWord;
     RequestData:         Pointer;
     RequestSize:         Word;
     RequestOptions:      PIPOptionInformation;
     ReplyBuffer:         Pointer;
     ReplySize:           DWord;
     Timeout:             DWord
  ): DWord; stdcall;const
  Size = 32;
  TimeOut = 1000;
var
  wsadata: TWSAData;
  Address: DWord;                     // Address of host to contact
  HostName, HostIP: String;           // Name and dotted IP of host to contact
  Phe: PHostEnt;                      // HostEntry buffer for name lookup
  BufferSize, nPkts: Integer;
  pReqData, pData: Pointer;
  pIPE: PIcmpEchoReply;               // ICMP Echo reply buffer
  IPOpt: TIPOptionInformation;        // IP Options for packet to send
const
  IcmpDLL = 'icmp.dll';
var
  hICMPlib: HModule;
  IcmpCreateFile : TIcmpCreateFile;
  IcmpCloseHandle: TIcmpCloseHandle;
  IcmpSendEcho:    TIcmpSendEcho;
  hICMP: THandle;                     // Handle for the ICMP Calls
begin
  // initialise winsock
  Result:=True;
  if WSAStartup(2,wsadata) <> 0 then begin
     Result:=False;
     halt;
  end;
  // register the icmp.dll stuff
  hICMPlib := loadlibrary(icmpDLL);
  if hICMPlib <> null then begin
    @ICMPCreateFile := GetProcAddress(hICMPlib, 'IcmpCreateFile');
    @IcmpCloseHandle:= GetProcAddress(hICMPlib, 'IcmpCloseHandle');
    @IcmpSendEcho:= GetProcAddress(hICMPlib, 'IcmpSendEcho');
    if (@ICMPCreateFile = Nil) or (@IcmpCloseHandle = Nil) or (@IcmpSendEcho = Nil) then begin
        Result:=False;
        halt;
    end;
    hICMP := IcmpCreateFile;
    if hICMP = INVALID_HANDLE_VALUE then begin
      Result:=False;
      halt;
    end;
  end else begin
    Result:=False;
    halt;
  end;
// ------------------------------------------------------------
  Address := inet_addr(PChar(IpAddr));
  if (Address = INADDR_NONE) then begin
    Phe := GetHostByName(PChar(IpAddr));
    if Phe = Nil then Result:=False
    else begin
      Address := longint(plongint(Phe^.h_addr_list^)^);
      HostName := Phe^.h_name;
      HostIP := StrPas(inet_ntoa(TInAddr(Address)));
    end;
  end
  else begin
    Phe := GetHostByAddr(@Address, 4, PF_INET);
    if Phe = Nil then Result:=False;
  end;  if Address = INADDR_NONE then
  begin
     Result:=False;
  end;
  // Get some data buffer space and put something in the packet to send
  BufferSize := SizeOf(TICMPEchoReply) + Size;
  GetMem(pReqData, Size);
  GetMem(pData, Size);
  GetMem(pIPE, BufferSize);
  FillChar(pReqData^, Size, $AA);
  pIPE^.Data := pData;    // Finally Send the packet
  FillChar(IPOpt, SizeOf(IPOpt), 0);
  IPOpt.TTL := 64;
  NPkts := IcmpSendEcho(hICMP, Address, pReqData, Size,
                        @IPOpt, pIPE, BufferSize, TimeOut);
  if NPkts = 0 then Result:=False;  // Free those buffers
  FreeMem(pIPE); FreeMem(pData); FreeMem(pReqData);// --------------------------------------------------------------
  IcmpCloseHandle(hICMP);
  FreeLibrary(hICMPlib);
  // free winsock
  if WSACleanup <> 0 then Result:=False;
end;

Answer 6

网络执法官用了winpcap包开发，基于ARP层，还没上升到IP层，所以可以看见所有网内的机器，不在一个网段也能看见，IP不行，用iphlpapl.dll中的SendArp，有响应就是开着机器，没有就是没联网
网上有代码

Answer 7

使用Indy Clients 下的 IdIcmpClient 组件应该可以满足你的要求：procedure   TForm1.FormCreate(Sender:   TObject);  
  begin  
    try  
      idicmpclient1.Host:='192.xxx.xxx.xxx';//對方機子  
      IdIcmpClient1.Ping();  
      if     IdIcmpClient1.ReplyStatus.FromIpAddress='192.xxx.xxx.xxx'   then  
      begin  
        ShowMessage('網絡通') 
      end  
      else  
      ShowMessage('網絡不通')  
    except  
      ShowMessage('網絡不通')  
    end;  
  end;