如何获取本机或者网关的互联网IP地址

 有两种情况，一种是本机直接接入互联网，比如通过拨号或者ADSL；另一种是局域网通过一个网关或者路由接入互联网；尤其是第二种情况，如何在局域网内的一台机器上获得当前网关所取得的互联网IP地址呢？

unit Functions; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs; function CheckInternetOnline: boolean; //检查互联网是否在线 function IsIP(S: string): boolean; //判断录入的字符串是否为IP function GetLocalIP: string; //获取本机IP地址 function GetTheInternetLocalIP: string; //获取外网IP地址 implementation uses GetInternetLocalIP,WinInet,Winsock; //HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH function CheckInternetOnline: boolean; //检查互联网是否在线 var ConnectState: DWORD; StateSize: DWORD; begin ConnectState := 0; StateSize := SizeOf(ConnectState); Result := false; //Use WinInet.pas; if InternetQueryOption(nil, INTERNET_OPTION_CONNECTED_STATE, @ConnectState, StateSize) then Result := (ConnectState and INTERNET_STATE_DISCONNECTED) <> 2; if Result then Result := InternetCheckConnection(\'http://www.microsoft.com/isapi/redir.dll?prd=ie&pver=6&ar=msnhome\', 1, 0); end; //HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH function IsIP(S: string): boolean; //判断录入的字符串是否为IP var S1, S2, S3, S4, sTemp: string; K, I: integer; begin S1 := \'\'; S2 := \'\'; S3 := \'\'; S4 := \'\'; K := 0; Result := false; S := Trim(S); if Length(S) < 7 then exit; //最小的IP长度也是7位0.0.0.0 for I := 0 to Length(S) do if S[I] = \'.\' then Inc(K); if K <> 3 then begin Result := false; exit; end else begin sTemp := S; for I := Length(sTemp) downto 1 do if sTemp[I] = \'.\' then Delete(sTemp, I, 1); for I := Length(sTemp) downto 1 do if not (sTemp[I] in [\'0\'..\'9\']) then begin Result := false; exit; end; K := Pos(\'.\', S); S1 := Copy(S, 1, K - 1); Delete(S, 1, K); K := Pos(\'.\', S); S2 := Copy(S, 1, K - 1); Delete(S, 1, K); K := Pos(\'.\', S); S3 := Copy(S, 1, K - 1); Delete(S, 1, K); S4 := S; Result := (StrToInt(S1) >= 0) and (StrToInt(S1) <= 255) and (StrToInt(S2) >= 0) and (StrToInt(S2) <= 255) and (StrToInt(S3) >= 0) and (StrToInt(S3) <= 255) and (StrToInt(S4) >= 0) and (StrToInt(S4) <= 255); end; end; //HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH function GetLocalIP: string; //获取本机IP地址 type TaPInAddr = array[0..255] of PInAddr; //Use Winsock.pas PaPInAddr = ^TaPInAddr; var phe: PHostEnt; pptr: PaPInAddr; Buffer: array[0..63] of char; i: integer; GInitData: TWSADATA; begin wsastartup($101, GInitData); result := \'\'; GetHostName(Buffer, SizeOf(Buffer)); phe := GetHostByName(buffer); if not assigned(phe) then exit; pptr := PaPInAddr(Phe^.h_addr_list); i := 0; while pptr^[I] <> nil do begin result := Result + StrPas(inet_ntoa(pptr^[I]^)) + \',\'; inc(i); end; Delete(Result, Length(Result), 1); wsacleanup; end; //HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH function GetTheInternetLocalIP: string; //获取外网IP地址 begin Result := \'\'; //Use GetInternetLocalIP.pas if not Assigned(GetInternetLocalIPForm) then if CheckInternetOnline then try Application.CreateForm(TGetInternetLocalIPForm, GetInternetLocalIPForm); while GetInternetLocalIPForm.TheInternetLocalIP = \'E\' do Application.ProcessMessages; Result := GetInternetLocalIPForm.TheInternetLocalIP; if not IsIP(Result) then Result := \'\'; finally FreeAndNil(GetInternetLocalIPForm); end; end; --------------------------------------------------------------------------------

1）简单。
2）论坛当中很多了。访问一个外部网址，得到互联网IP地址呢