计算机科学论坛--[转帖]sniffer技术原理及应用,包括编程方法和工具使用（二）

winpcap也是用的NDIS，将自己注册为一个协议处理驱动。(在原代码的driverentry里面能看到)又：上面这个drvipflt这个代码的过滤部分不知道大家是不是看起来很熟悉，是的，是抄的那个numege的驱动开发包里面的一个包过滤程序里的，看来老外也是喜欢到处抄的。

ruike:
读研的时候专门搞过nids，因此对winpcap可以说是情有独钟，这个东东确实好用，但也确实很烦人，它有一个致命的缺陷就是只适用于共享式以太网络，对于交换式网络下的数据则无能为力，我专门做过测试，在使用交换机连接的局域网下，只能监听到本网段内的数据，而对于来自其他网段的数据则无法监听，除非你把probe接到交换机之前或者接到交换机的console口上，不过那样的弊端是显而易见的。
所以，winpcap的应用还是很有局限性的！

kingzai:
实现交换网络的嗅探也有不少方法的
1.将你的抓包程序放在网关或代理服务器上，这样抓到整个局域网的包。
2.对交换机实行端口映射，将该端口的数据包全部映射到某个监控机器上。
3.在交换机和路由器之间连接一个HUB,这样数据将以广播的方式发送。
4.实行ARP欺骗，即在你的机器上实现整个包的转发，不过会降低整个局域网的效率。

warton:
嗅探对策：
光说嗅探了，我说说反嗅探吧：）
1.检查网内的主机上是否将网卡设置为混合模式（有很多工具可以做到，AntiSniff,Promiscan,Sentinel等）
2.对EtterCap这样的交换网络嗅探器（进行ARP欺骗），可以采用防止ARP欺骗的方法来对待
3.SSH加密通道
4.SSL
5.VPN
6.PGP等

目前这用利用网卡混合模式来进行sniffer的软件看来作用不太大了，所以应该多考虑交换网络的可行办法：

MAC Flooding,MAC Duplicating,ARP欺骗等等
这些方法实现起来就不怎么容易了，欢迎有兴趣的朋友提供相关的资料，呵呵！

netsys:
难道没人用过RAW SOCKET 吗？
虽然WINPCP功能很大，但RAW SOCKET可以让你直接了SOCKET的原生机制。
实际上我提的那两个问题是很容易解决的。。

netsys2:
对于一些混合模式的SNIFFER，大多采用发送特殊ARP包的方式，正确的网卡不会响应，而处于混合模式的网卡则会响应。当然，ARP与IP处于同层，因此你不能用RAW SOCKET完成，你需WinPcap支持工作。

下面是部分代码

AnsiString msgStatus;
extern TArpFuncParam wParams;

int BuildARPPacket(PArpPacket ArpPacket, unsigned char *dst_etheraddr,
unsigned char *src_etheraddr, int ar_op, unsigned

char *ar_sha,
     unsigned char *ar_sip, unsigned char *ar_tha,
                          unsigned char *ar_tip,unsigned short int ar_hw)
{
  memcpy(&(ArpPacket->eth_dst_addr), dst_etheraddr, ETH_ADD_LEN);
  memcpy(&(ArpPacket->eth_src_addr), src_etheraddr, ETH_ADD_LEN);
  ArpPacket->eth_type = htons(ETH_TYPE_ARP);
  ArpPacket->ar_hrd = htons(ar_hw);
  ArpPacket->ar_pro = htons(ARP_PRO_IP);
  ArpPacket->ar_hln = ARP_ETH_ADD_SPACE;
  ArpPacket->ar_pln = ARP_IP_ADD_SPACE;
  ArpPacket->ar_op  = htons(ar_op);
  memcpy(&(ArpPacket->ar_sha), ar_sha, ARP_ETH_ADD_SPACE);
  memcpy(&(ArpPacket->ar_spa), ar_sip, ARP_IP_ADD_SPACE);
  memcpy(&(ArpPacket->ar_tha), ar_tha, ARP_ETH_ADD_SPACE);
  memcpy(&(ArpPacket->ar_tpa), ar_tip, ARP_IP_ADD_SPACE);
  memset(ArpPacket->eth_pad, 32, ETH_PADDING_ARP);
  return(EXIT_SUCCESS);
}
int OpenAdapter(LPADAPTER *lpAdapter)
{
  *lpAdapter =

PacketOpenAdapter(wParams.AdapterList[wParams.SelectedAdapter]);

  if(!(*lpAdapter) || ((*lpAdapter)->hFile == INVALID_HANDLE_VALUE))
  {
    msgStatus = "Error : unable to open the driver.";
    SHOWSTAT(msgStatus);
    return(EXIT_FAILURE);
  }
  return(EXIT_SUCCESS);
}
void CloseAdapter(LPADAPTER lpAdapter)
{
  PacketCloseAdapter(lpAdapter);

}
void GetLocalMAC(LPADAPTER lpAdapter, unsigned char *ether_addr)
{

ULONG IoCtlBufferLength = (sizeof(PACKET_OID_DATA) + sizeof(ULONG) - 1);
PPACKET_OID_DATA OidData;

  OidData = (struct _PACKET_OID_DATA *)malloc(IoCtlBufferLength);
  OidData->Oid = OID_802_3_CURRENT_ADDRESS;
  OidData->Length = 6;
  if(PacketRequest(lpAdapter, FALSE, OidData) == FALSE)
      memcpy(ether_addr, 0, 6);
  else
      memcpy(ether_addr, OidData->Data, 6);
  free(OidData);
}
int GetARPReply(LPPACKET lpPacket, unsigned char *iptarget, unsigned char

*result)
{
  unsigned short int ether_type;
  unsigned char      ipsender[4];
  unsigned int       off=0;
  unsigned int       tlen;
  struct bpf_hdr     *hdr;
  char              *pChar;
  char              *buf;

  buf = (char *)lpPacket->Buffer;
  hdr = (struct bpf_hdr *)(buf + off);
  tlen = hdr->bh_caplen;
  off += hdr->bh_hdrlen;
  pChar = (char*)(buf + off);
  off = Packet_WORDALIGN(off + tlen);
  memcpy(&ether_type, pChar + 12, 2);
  ether_type = ntohs(ether_type);
  if(ether_type == ETH_TYPE_ARP)
  {
    memcpy(ipsender, pChar + 28, 4);
    if((iptarget[0] == ipsender[0])&&(iptarget[1] == ipsender[1])&&
       (iptarget[2] == ipsender[2])&&(iptarget[3] == ipsender[3]))
      memcpy(result, pChar + 22, 6);
    else
        return(EXIT_FAILURE);
  }
  else
      return(EXIT_FAILURE);
return(EXIT_SUCCESS);
}
int CheckPROMode(LPADAPTER lpAdapter, unsigned char *iptarget, unsigned char

*remotemac)
{

  LPPACKET lpPacketRequest;
  LPPACKET lpPacketReply;
  char     buffer[256000];

  TArpPacket ArpPacket;
  unsigned char magicpack[ETH_ADD_LEN]= {0xFF,0xFF,0xFF,0xFF,0xFF,0xFE};
  unsigned char mactarget[ARP_ETH_ADD_SPACE];

  DWORD timestamp = 0;
  int numPacks = 0;
  /* Init fields */
  memset(mactarget, 0, 6);
  /* Allocate PACKET structure for ARP Request packet */
  if((lpPacketRequest = PacketAllocatePacket()) == NULL)
  {
    msgStatus =  "Error : failed to allocate the LPPACKET structure..";
    SHOWSTAT(msgStatus);
    return(EXIT_FAILURE);
  }

/* Init packet structure */
memset(&ArpPacket, 0, sizeof(TArpPacket));

/* Build ARP Request packet */
BuildARPPacket(&ArpPacket, magicpack, wParams.srcMAC, ARP_OP_REQUEST,

wParams.srcMAC, wParams.srcIPAdd, mactarget, iptarget,wParams.ar_hw);

  /* Init ARP Request packet */
  PacketInitPacket(lpPacketRequest, &ArpPacket, sizeof(ArpPacket));

  /* Set number of ARP Request packets to send */
  if(PacketSetNumWrites(lpAdapter, 1) == FALSE)
  {
    msgStatus = "Warning : unable to send more than one packet in a single write..";
    SHOWSTAT(msgStatus);
  }
  /* Set hardware filter to directed mode */
  if(PacketSetHwFilter(lpAdapter, NDIS_PACKET_TYPE_DIRECTED) == FALSE)
  {
    msgStatus ="Warning: unable to set directed mode..";
    SHOWSTAT(msgStatus);
  }
  /* Set a 512K buffer in the driver */
  if(PacketSetBuff(lpAdapter, 512000) == FALSE)
  {
    msgStatus = "Error: unable to set the kernel buffer..";
    SHOWSTAT(msgStatus);
    PacketFreePacket(lpPacketRequest);
    return(EXIT_FAILURE);
  }
  /* Set a 1 second read timeout */
  if(PacketSetReadTimeout(lpAdapter, -1) == FALSE)
  {
    msgStatus = "Warning: unable to set the read tiemout..";
    SHOWSTAT(msgStatus);
  }

  /* Allocate PACKET structure for ARP Reply packet */
  if((lpPacketReply = PacketAllocatePacket()) == NULL)
  {
    msgStatus = "Error: failed to allocate the LPPACKET structure..";
    SHOWSTAT(msgStatus);
    PacketFreePacket(lpPacketRequest);
    return(EXIT_FAILURE);
  }
  /* Init ARP Reply packet */
  PacketInitPacket(lpPacketReply, (char*)buffer, 256000);
  /* Allocate memory for remote MAC address */
  timestamp = GetTickCount();

  /* Main capture loop */
  for(;;)
  {
    if(numPacks < wParams.numPacks)
    {
   /* Send packet */
      if(PacketSendPacket(lpAdapter, lpPacketRequest, TRUE) == FALSE)
      {
        msgStatus ="Error : unable to send the packets..";
        SHOWSTAT(msgStatus);
        PacketFreePacket(lpPacketRequest);
        PacketFreePacket(lpPacketReply);
        return(EXIT_FAILURE);
      }
      /* Free packet */
      PacketFreePacket(lpPacketRequest);
      numPacks += 1;
    }
    /* Capture the packets */
    if(PacketReceivePacket(lpAdapter, lpPacketReply, TRUE) == FALSE)
    {
        msgStatus = "Error: PacketReceivePacket failed..";
        SHOWSTAT(msgStatus);
PacketFreePacket(lpPacketReply);
   return(EXIT_FAILURE);
    }
    if(lpPacketReply->ulBytesReceived > 0)
   if(GetARPReply(lpPacketReply, iptarget, remotemac) == EXIT_SUCCESS)
         break;
    if((GetTickCount() - timestamp) > wParams.delay)
    {
      PacketFreePacket(lpPacketReply);
      return(EXIT_FAILURE);
    }
  }
  /* Free packet */
  PacketFreePacket(lpPacketReply);
  return(EXIT_SUCCESS);
}


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