IP地址的隐藏   一、前言   　 本文主要介绍如何在程序中实现IP地址的隐藏。其实这篇东西不算我写的。其中《IP头结构》部分我懒得打字，故复制、粘贴了孤独剑客的文章，先说声谢谢！代码部分参考了外国程序xes写的一个程序。所以这只是学习过程中的一个副产品。既然程序已经做好了，就顺便放上来跟大家一起交流，共同提高吧。本文只不过想说明一下IP数据的结构和发送机制。如果有人把它改为恶意IP攻击工具，后果自负。   二、IP头结构        我们知道，TCP/IP网络数据全部是通过封装在IP数据包中在Internet网上传送的，也就是封装建立起一个包含IP头和数据的IP数据报。一般来说，网络软件总是以多个32位字产生IP头，即使必须用附加的0填充IP头。IP头包含了传输IP数据包中封装数据的所有必要信息。IP头的数据结构和描述如下：     成员 长度(Bit) 描述   Version 4 IP头的版本号，目前是IPv4，最新是IPv6   Header Length 4 IP头的长度，若没有特殊选择，IP头总是20字节长   Type of Service 8 服务类型，定义了数据传输的优先级、延迟、吞吐量和可靠性等特性   Total Packet Length 16 IP包的长度，若没有特殊选项，一般为20字节长   Identification 16 IP包标识，主机使用它唯一确定每个发送的数据报   Flag 3 IP数据分割标志   Fragment Offset 13 IP数据分割偏移   Time to Live 8 数据报在网络上的存活时间，每通过一个路由器，该数值减一   Protocol 8 TCP/IP协议类型，比如：ICMP为1，IGMP为2，TCP为6，UDP为17等   Header Checksum 16 头部检验和   Source IP Address 32 源IP地址   Destination IP Address 32 目的IP地址   Other ? 其他选项   Data ? 数据        实现自己定义的IP头是一件非常有意义的事情，比如，通过改变IP头里的TOS的优先级和TTL，你可以使自己的数据包有更强的传输能力和寿命，通过修改IP头里的源IP地址就可以隐藏自己机器的IP地址等等。象著名攻击程序“泪滴TearDrop”就是通过故意制造系统不能处理的分片IP包而实现的，还有SYN Flooder和UDP Flooder就是通过产生随机源IP实现欺骗的。   三、实现原理        一般来说，自定义IP头是通过使用socket的库函数setsockopt()的选项IP_HDRINCL来实现的，尽管这在unix和linux平台上很容易实现，但遗憾的是在Windows平台的Winsock1.1和Winsock2.0函数库里setsockopt()不支持IP_HDRINCL选项，所以在Windows 9x/NT里是无法通过Winsock函数库来实现IP头自定义的，当然可以通过编写虚拟设备驱动程序来实现，不过比较复杂，但Windows 2000的出现打破了这种局面，Windows2000的Winsock2.2函数库里全面支持setsockopt()的选项IP_HDRINCL，使得我们轻松就可以实现自定义的IP头。实现方法如下：   四、代码部分   {  1. 本程序只能运行于 Window 2000.  2. 你必须有 Administrator 权限.  3. 程序需要用到一个 button 和一个 memo.  ----------------------------------------------------------------------  运行程序前，请根据自己的需要改变 SrcIP、SrcPort、DestIP和DestPort的值  ----------------------------------------------------------------------  如果你看不懂以下代码，最好不要去运行它。  ----------------------------------------------------------------------  }   unit Unit1;   interface   uses   Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,   StdCtrls, OleCtrls, Registry;     Const   SrcIP = ‘123.123.123.1‘;//发送方IP地址   SrcPort = 1234;         file://发送方端口   DestIP = ‘127.0.0.2‘;   file://目的IP地址   DestPort = 4321;        file://目的端口     Max_Message = 4068;   Max_Packet = 4096;     type     TPacketBuffer = Array[0..Max_Packet-1] of byte;     TForm1 = class(TForm)   Button1: TButton;   Memo1: TMemo;   procedure Button1Click(Sender: TObject);   private   { Private declarations }   public   { Public declarations }   procedure SendIt;   end;     // IP 头   type   T_IP_Header = record   ip_verlen : Byte;   ip_tos : Byte;   ip_totallength : Word;   ip_id : Word;   ip_offset : Word;   ip_ttl : Byte;   ip_protocol : Byte;   ip_checksum : Word;   ip_srcaddr : LongWord;   ip_destaddr : LongWord;   end;     // UDP 头   Type   T_UDP_Header = record   src_portno : Word;   dst_portno : Word;   udp_length : Word;   udp_checksum : Word;   end;     // 一些 Winsock 2 的类型声明   u_char = Char;   u_short = Word;   u_int = Integer;   u_long = Longint;     SunB = packed record   s_b1, s_b2, s_b3, s_b4: u_char;   end;   SunW = packed record   s_w1, s_w2: u_short;   end;   in_addr = record   case integer of   0: (S_un_b: SunB);   1: (S_un_w: SunW);   2: (S_addr: u_long);   end;   TInAddr = in_addr;   Sockaddr_in = record   case Integer of   0: (sin_family: u_short;   sin_port: u_short;   sin_addr: TInAddr;   sin_zero: array[0..7] of Char);   1: (sa_family: u_short;   sa_data: array[0..13] of Char)   end;   TSockAddr = Sockaddr_in;   TSocket = u_int;     const   WSADESCRIPTION_LEN = 256;   WSASYS_STATUS_LEN = 128;     type   PWSAData = ^TWSAData;   WSAData = record //  WSDATA   wVersion: Word;   wHighVersion: Word;   szDescription: array[0..WSADESCRIPTION_LEN] of Char;   szSystemStatus: array[0..WSASYS_STATUS_LEN] of Char;   iMaxSockets: Word;   iMaxUdpDg: Word;   lpVendorInfo: PChar;   end;   TWSAData = WSAData;     file://定义一些 winsock 2 函数   function closesocket(s: TSocket): Integer; stdcall;   function socket(af, Struct, protocol: Integer): TSocket; stdcall;   function sendto(s: TSocket; var Buf; len, flags: Integer; var addrto: TSockAddr;   tolen: Integer): Integer; stdcall;{}   function setsockopt(s: TSocket; level, optname: Integer; optval: PChar;   optlen: Integer): Integer; stdcall;   function inet_addr(cp: PChar): u_long; stdcall; {PInAddr;} { TInAddr }   function htons(hostshort: u_short): u_short; stdcall;   function WSAGetLastError: Integer; stdcall;   function WSAStartup(wVersionRequired: word; var WSData: TWSAData): Integer; stdcall;   function WSACleanup: Integer; stdcall;     const   AF_INET = 2; // internetwork: UDP, TCP, etc.     IP_HDRINCL = 2; // IP Header Include     SOCK_RAW = 3; // raw-protocol interface     IPPROTO_IP = 0; // dummy for IP   IPPROTO_TCP = 6; // tcp   IPPROTO_UDP = 17; // user datagram protocol   IPPROTO_RAW = 255; // raw IP packet     INVALID_SOCKET = TSocket(NOT(0));   SOCKET_ERROR = -1;     var   Form1: TForm1;     implementation     // Import Winsock 2 functions   const WinSocket = ‘WS2_32.DLL‘;     function closesocket; external winsocket name ‘closesocket‘;   function socket; external winsocket name ‘socket‘;   function sendto; external winsocket name ‘sendto‘;   function setsockopt; external winsocket name ‘setsockopt‘;   function inet_addr; external winsocket name ‘inet_addr‘;   function htons; external winsocket name ‘htons‘;   function WSAGetLastError; external winsocket name ‘WSAGetLastError‘;   function WSAStartup; external winsocket name ‘WSAStartup‘;   function WSACleanup; external winsocket name ‘WSACleanup‘;       {$R *.DFM}     function CheckSum(Var Buffer; Size : integer) : Word;   type   TWordArray = Array[0..1] of Word;   var   ChkSum : LongWord;   i : Integer;   begin   ChkSum := 0;   i := 0;   While Size > 1 do begin   ChkSum := ChkSum + TWordArray(Buffer);   inc(i);   Size := Size - SizeOf(Word);   end;     if Size=1 then ChkSum := ChkSum + Byte(TWordArray(Buffer));     ChkSum := (ChkSum shr 16) + (ChkSum and $FFFF);   ChkSum := ChkSum + (Chksum shr 16);     Result := Word(ChkSum);   end;       procedure BuildHeaders(   FromIP : String;   iFromPort : Word;   ToIP : String;   iToPort : Word;   StrMessage : String;   Var Buf : TPacketBuffer;   Var remote : TSockAddr;   Var iTotalSize : Word   );   Var   dwFromIP : LongWord;   dwToIP : LongWord;     iIPVersion : Word;   iIPSize : Word;   ipHdr : T_IP_Header;   udpHdr : T_UDP_Header;     iUdpSize : Word;   iUdpChecksumSize : Word;   cksum : Word;     Ptr : ^Byte;     procedure IncPtr(Value : Integer);   begin   ptr := pointer(integer(ptr) + Value);   end;     begin   // Convert ip address‘ss     dwFromIP := inet_Addr(PChar(FromIP));   dwToIP := inet_Addr(PChar(ToIP));     // 初始化 IP 头   //   iTotalSize := sizeof(ipHdr) + sizeof(udpHdr) + length(strMessage);     iIPVersion := 4;   iIPSize := sizeof(ipHdr) div sizeof(LongWord);     ipHdr.ip_verlen := (iIPVersion shl 4) or iIPSize;   ipHdr.ip_tos := 0; // IP type of service   ipHdr.ip_totallength := htons(iTotalSize); // Total packet len   ipHdr.ip_id := 0; // Unique identifier: set to 0   ipHdr.ip_offset := 0; // Fragment offset field   ipHdr.ip_ttl := 128; // Time to live   ipHdr.ip_protocol := $11; // Protocol(UDP)   ipHdr.ip_checksum := 0 ; // IP checksum   ipHdr.ip_srcaddr := dwFromIP; // Source address   ipHdr.ip_destaddr := dwToIP; // Destination address   //   // 初始化 UDP 头   //   iUdpSize := sizeof(udpHdr) + length(strMessage);     udpHdr.src_portno := htons(iFromPort) ;   udpHdr.dst_portno := htons(iToPort) ;   udpHdr.udp_length := htons(iUdpSize) ;   udpHdr.udp_checksum := 0 ;     iUdpChecksumSize := 0;     ptr := @buf[0];   FillChar(Buf, SizeOf(Buf), 0);     Move(ipHdr.ip_srcaddr, ptr^, SizeOf(ipHdr.ip_srcaddr));   IncPtr(SizeOf(ipHdr.ip_srcaddr));     iUdpChecksumSize := iUdpChecksumSize + sizeof(ipHdr.ip_srcaddr);     Move(ipHdr.ip_destaddr, ptr^, SizeOf(ipHdr.ip_destaddr));   IncPtr(SizeOf(ipHdr.ip_destaddr));     iUdpChecksumSize := iUdpChecksumSize + sizeof(ipHdr.ip_destaddr);     IncPtr(1);     Inc(iUdpChecksumSize);     Move(ipHdr.ip_protocol, ptr^, sizeof(ipHdr.ip_protocol));   IncPtr(sizeof(ipHdr.ip_protocol));   iUdpChecksumSize := iUdpChecksumSize + sizeof(ipHdr.ip_protocol);     Move(udpHdr.udp_length, ptr^, sizeof(udpHdr.udp_length));   IncPtr(sizeof(udpHdr.udp_length));   iUdpChecksumSize := iUdpChecksumSize + sizeof(udpHdr.udp_length);     move(udpHdr, ptr^, sizeof(udpHdr));   IncPtr(sizeof(udpHdr));   iUdpChecksumSize := iUdpCheckSumSize + sizeof(udpHdr);     Move(StrMessage[1], ptr^, Length(strMessage));   IncPtr(Length(StrMessage));     iUdpChecksumSize := iUdpChecksumSize + length(strMessage);     cksum := checksum(buf, iUdpChecksumSize);   udpHdr.udp_checksum := cksum;     //   // 现在 IP 和 UDP 头OK了，我们可以把它发送出去。   //   FillChar(Buf, SizeOf(Buf), 0);   Ptr := @Buf[0];     Move(ipHdr, ptr^, SizeOf(ipHdr)); IncPtr(SizeOf(ipHdr));   Move(udpHdr, ptr^, SizeOf(udpHdr)); IncPtr(SizeOf(udpHdr));   Move(StrMessage[1], ptr^, length(StrMessage));       remote.sin_family := AF_INET;   remote.sin_port := htons(iToPort);   remote.sin_addr.s_addr := dwToIP;   end;     procedure TForm1.SendIt;   Var   sh : TSocket;   bOpt : Integer;   ret : Integer;   Buf : TPacketBuffer;   Remote : TSockAddr;   Local : TSockAddr;   iTotalSize : Word;   wsdata : TWSAdata;     begin   // Startup Winsock 2   ret := WSAStartup($0002, wsdata);   if ret<>0 then begin   memo1.lines.add(‘WSA Startup failed.‘);   exit;   end;   with memo1.lines do begin   add(‘WSA Startup:‘);   add(‘Desc.: ‘+wsData.szDescription);   add(‘Status: ‘+wsData.szSystemStatus);   end;     try   // Create socket   sh := Socket(AF_INET, SOCK_RAW, IPPROTO_UDP);   if (sh = INVALID_SOCKET) then begin   memo1.lines.add(‘Socket() failed: ‘+IntToStr(WSAGetLastError));   exit;   end;   Memo1.lines.add(‘Socket Handle = ‘+IntToStr(sh));     // Option: Header Include   bOpt := 1;   ret := SetSockOpt(sh, IPPROTO_IP, IP_HDRINCL, @bOpt, SizeOf(bOpt));   if ret = SOCKET_ERROR then begin   Memo1.lines.add(‘setsockopt(IP_HDRINCL) failed: ‘+IntToStr(WSAGetLastError));   exit;   end;     // Build the packet   BuildHeaders( SrcIP, SrcPort,   DestIP, DestPort,   ‘THIS IS A TEST PACKET‘,   Buf, Remote, iTotalSize );     // Send the packet   ret := SendTo(sh, buf, iTotalSize, 0, Remote, SizeOf(Remote));   if ret = SOCKET_ERROR then   Memo1.Lines.Add(‘sendto() failed: ‘+IntToStr(WSAGetLastError))   else   Memo1.Lines.Add(‘send ‘+IntToStr(ret)+‘ bytes.‘);     // Close socket   CloseSocket(sh);   finally   // Close Winsock 2   WSACleanup;   end;   end;     procedure TForm1.Button1Click(Sender: TObject);   begin   SendIt;   end;     end.