[摘要]五. 实现 Sniffer OK! 现在都清楚了, 还等什么. 下面是我用 BCB6 写的一个 Simple Sniffer 的代码, 仅供参考. （需要在工程文件里加入WS2_32...
五. 实现 Sniffer
OK!
现在都清楚了, 还等什么.
下面是我用 BCB6 写的一个 Simple Sniffer 的代码, 仅供参考.
（需要在工程文件里加入WS2_32.LIB这个文件）
//*************************************************************************//
//* CPP File: WMain.cpp
//* Simple Sniffer by shadowstar
//* http://shadowstar.126.com/
//*************************************************************************//
#include <vcl.h>
#pragma hdrstop
#include <winsock2.h>
#include <ws2tcpip.h>
#include <mstcpip.h>
#include <netmon.h>
#include "WMain.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TMainForm *MainForm;
//---------------------------------------------------------------------------
__fastcall TMainForm::TMainForm(TComponent* Owner)
: TForm(Owner)
{
WSADATA WSAData;
BOOL flag = true;
int nTimeout = 1000;
char LocalName[16];
struct hostent *pHost;
//检查 Winsock 版本号
if (WSAStartup(MAKEWORD(2, 2), &WSAData) != 0)
throw Exception("WSAStartup error!");
//初始化 Raw Socket
if ((sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) == INVALID_SOCKET)
throw Exception("socket setup error!");
//设置IP头操作选项
if (setsockopt(sock, IPPROTO_IP, IP_HDRINCL, (char*)&flag, sizeof(flag)) == SOCKET_ERROR)
throw Exception("setsockopt IP_HDRINCL error!");
//获取本机名
if (gethostname((char*)LocalName, sizeof(LocalName)-1) == SOCKET_ERROR)
throw Exception("gethostname error!");
//获取本地 IP 地址
if ((pHost = gethostbyname((char*)LocalName)) == NULL)
throw Exception("gethostbyname error!");
addr_in.sin_addr = *(in_addr *)pHost->h_addr_list[0]; //IP
addr_in.sin_family = AF_INET;
addr_in.sin_port = htons(57274);
//把 sock 绑定到本地地址上
if (bind(sock, (PSOCKADDR)&addr_in, sizeof(addr_in)) == SOCKET_ERROR)
throw Exception("bind error!");
iSortDirection = 1;
}
//---------------------------------------------------------------------------
__fastcall TMainForm::~TMainForm()
{
WSACleanup();
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::btnCtrlClick(TObject *Sender)
{
TListItem *Item;
DWORD dwValue;
int nIndex = 0;
if (btnCtrl->Caption == "&Start")
{
dwValue = 1;
//设置 SOCK_RAW 为SIO_RCVALL，以便接收所有的IP包
if (ioctlsocket(sock, SIO_RCVALL, &dwValue) != 0)
throw Exception("ioctlsocket SIO_RCVALL error!");
bStop = false;
btnCtrl->Caption = "&Stop";
lsvPacket->Items->Clear();
}
else
{
dwValue = 0;
bStop = true;
btnCtrl->Caption = "&Start";
//设置SOCK_RAW为SIO_RCVALL，停止接收
if (ioctlsocket(sock, SIO_RCVALL, &dwValue) != 0)
throw Exception("WSAIoctl SIO_RCVALL error!");
}
while (!bStop)
{
if (recv(sock, RecvBuf, BUFFER_SIZE, 0) > 0)
{
nIndex++;
ip = *(IP*)RecvBuf;
tcp = *(TCP*)(RecvBuf + (ip.HdrLen & IP_HDRLEN_MASK));
Item = lsvPacket->Items->Add();
Item->Caption = nIndex;
Item->SubItems->Add(GetProtocolTxt(ip.Protocol));
Item->SubItems->Add(inet_ntoa(*(in_addr*)&ip.SrcAddr));
Item->SubItems->Add(inet_ntoa(*(in_addr*)&ip.DstAddr));
Item->SubItems->Add(tcp.SrcPort);
Item->SubItems->Add(tcp.DstPort);
Item->SubItems->Add(ntohs(ip.TotalLen));
}
Application->ProcessMessages();
}
}
//---------------------------------------------------------------------------
AnsiString __fastcall TMainForm::GetProtocolTxt(int Protocol)
{
switch (Protocol)
{
case IPPROTO_ICMP : //1 /* control message protocol */
return PROTOCOL_STRING_ICMP_TXT;
case IPPROTO_TCP : //6 /* tcp */
return PROTOCOL_STRING_TCP_TXT;
case IPPROTO_UDP : //17 /* user datagram protocol */
return PROTOCOL_STRING_UDP_TXT;
default :
return PROTOCOL_STRING_UNKNOWN_TXT;
}
}
//---------------------------------------------------------------------------
//*************************************************************************//
//* Header File: WMain.h for WMain.cpp class TMainForm
//*************************************************************************//
//---------------------------------------------------------------------------
#ifndef WMainH
#define WMainH
//---------------------------------------------------------------------------
#define BUFFER_SIZE 65535
#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>
#include <ComCtrls.hpp>
#include <ExtCtrls.hpp>
#include <winsock2.h>
#include "netmon.h"
//---------------------------------------------------------------------------
class TMainForm : public TForm
{
__published: // IDE-managed Components
TPanel *Panel1;
TButton *btnCtrl;
TListView *lsvPacket;
TLabel *Label1;
void __fastcall btnCtrlClick(TObject *Sender);
void __fastcall lsvPacketColumnClick(TObject *Sender,
TListColumn *Column);
void __fastcall lsvPacketCompare(TObject *Sender, TListItem *Item1,
TListItem *Item2, int Data, int &Compare);
void __fastcall Label1Click(TObject *Sender);
private: // User declarations
AnsiString __fastcall GetProtocolTxt(int Protocol);
public: // User declarations
SOCKET sock;
SOCKADDR_IN addr_in;
IP ip;
TCP tcp;
PSUHDR psdHeader;
char RecvBuf[BUFFER_SIZE];
bool bStop;
int iSortDirection;
int iColumnToSort;
__fastcall TMainForm(TComponent* Owner);
__fastcall ~TMainForm();
};
//---------------------------------------------------------------------------
extern PACKAGE TMainForm *MainForm;
//---------------------------------------------------------------------------
#endif
偷了个懒, IP, TCP 头及一些宏定义用了 netmon.h 的头, 这个文件在 BCB6 的 include 目录下可以找得到, 其中与本程序相关内容如下:
//*************************************************************************//
//* Header File: netmon.h
//*************************************************************************//
//
// IP Packet Structure
//
typedef struct _IP
{
union
{
BYTE Version;
BYTE HdrLen;
};
BYTE ServiceType;
WORD TotalLen;
WORD ID;
union
{
WORD Flags;
WORD FragOff;
};
BYTE TimeToLive;
BYTE Protocol;
WORD HdrChksum;
DWORD SrcAddr;
DWORD DstAddr;
BYTE Options[0];
} IP;
typedef IP * LPIP;
typedef IP UNALIGNED * ULPIP;
//
// TCP Packet Structure
//
typedef struct _TCP
{
WORD SrcPort;
WORD DstPort;
DWORD SeqNum;
DWORD AckNum;
BYTE DataOff;
BYTE Flags;
WORD Window;
WORD Chksum;
WORD UrgPtr;
} TCP;
typedef TCP *LPTCP;
typedef TCP UNALIGNED * ULPTCP;
// upper protocols
#define PROTOCOL_STRING_ICMP_TXT "ICMP"
#define PROTOCOL_STRING_TCP_TXT "TCP"
#define PROTOCOL_STRING_UDP_TXT "UDP"
#define PROTOCOL_STRING_SPX_TXT "SPX"
#define PROTOCOL_STRING_NCP_TXT "NCP"
#define PROTOCOL_STRING_UNKNOW_TXT "UNKNOW"
这个文件也有人声称没有.
//*************************************************************************//
//* Header File: mstcpip.h
//*************************************************************************//
// Copyright (c) Microsoft Corporation. All rights reserved.
#if _MSC_VER > 1000
#pragma once
#endif
/* Argument structure for SIO_KEEPALIVE_VALS */
struct tcp_keepalive {
u_long onoff;
u_long keepalivetime;
u_long keepaliveinterval;
};
// New WSAIoctl Options
#define SIO_RCVALL _WSAIOW(IOC_VENDOR,1)
#define SIO_RCVALL_MCAST _WSAIOW(IOC_VENDOR,2)
#define SIO_RCVALL_IGMPMCAST _WSAIOW(IOC_VENDOR,3)
#define SIO_KEEPALIVE_VALS _WSAIOW(IOC_VENDOR,4)
#define SIO_ABSORB_RTRALERT _WSAIOW(IOC_VENDOR,5)
#define SIO_UCAST_IF _WSAIOW(IOC_VENDOR,6)
#define SIO_LIMIT_BROADCASTS _WSAIOW(IOC_VENDOR,7)
#define SIO_INDEX_BIND _WSAIOW(IOC_VENDOR,8)
#define SIO_INDEX_MCASTIF _WSAIOW(IOC_VENDOR,9)
#define SIO_INDEX_ADD_MCAST _WSAIOW(IOC_VENDOR,10)
#define SIO_INDEX_DEL_MCAST _WSAIOW(IOC_VENDOR,11)
// Values for use with SIO_RCVALL* options
#define RCVALL_OFF 0
#define RCVALL_ON 1
#define RCVALL_SOCKETLEVELONLY 2
现在我们自已的 Sniffer 就做好了, Run, Start......哇, 这么多数据包, 都是从这一台机器上发出的, 它在干什么? 原来 Adminstrator 密码为空, 中了尼姆达病毒!
六. 小结
优点: 实现简单, 不需要做驱动程序就可实现抓包.
缺点: 数据包头不含帧信息, 不能接收到与 IP 同层的其它数据包, 如 ARP, RARP...
这里提供的程序仅仅是一个 Sniffer 的例子, 没有对数据包进行进一步的分析. 写此文的目的在于熟悉Raw Socket 编程方法, 了解 TCP/IP 协议结构原理以及各协议之间的关系.
关键词：Raw Socket（原始套接字）完成Sniffer（嗅探）