认识pcap_t
实例
 handle = {
  fd = 7,        // 文件描述符
  snapshot = 
8192, 
  linktype = 1,    // LINKTYPE_ETHERNET 1 
链路层的类型
  tzoff = 0,    /* timezone offset */
  offset = 
2,      /* offset for proper alignment */
  sf = 
{    // struct pcap_sf sf; sf =  savefile
    rfile = 
0x0,  // File *
    swapped = 0, 
    
version_major = 0, 
    version_minor = 0, 
    base = 0x0
  }, 
  md = {   // 
struct pcap_md md;
    stat = { //  struct pcap_stat 
stat; As returned by the pcap_stats() 
      ps_recv 
= 0,  /* number of packets received */
      
ps_drop = 0, /* number of packets dropped */
      
ps_ifdrop = 0 /* drops by interface XXX not yet supported 
*/
    }, 
    use_bpf = 0,  // 
    TotPkts = 0,  /* can‘t oflow for 79 hrs on ether 
*/
    TotAccepted = 0,  /* count accepted by filter 
*/
    TotDrops = 0,      /* count of 
dropped packets */
    TotMissed = 0,    /* 
missed by i/f during this run */
    OrigMissed = 0,  /* 
missed by i/f before this run */
    pad = 0, 
    skip = 0, 
    device = 0x80627a8 
"eth0" // 使用哪个设备
  }, 
  bufsize = 1564,   // buf的大小
  
buffer = 0x8062180 "",  // buffer的指向
  bp = 0x0, 
  cc = 0, 
  pkt = 0x0,     //  Place holder for pcap_next().
  fcode 
= {   // Placeholder for filter code if bpf not in 
kernel.
    bf_len = 0, 
    bf_insns = 
0x0
  }, 
  errbuf = ‘\000‘ <repeats 255 times> // 
错误信息
}
原文:http://www.cnblogs.com/kwingmei/p/3622224.html