【VS开发】【Linux开发】【DSP开发】如何截获以太网帧并解析

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/* capture_packet.c - 截获所有以太网帧数据并进行具体分析 */   /* 常用函数的头文件   */ #include <stdio.h> #include <stdlib.h> #include <string.h>  #include <strings.h> #include <unistd.h>  #include <signal.h>   /* 与网络相关的头文件 */ #include <netinet/ip_icmp.h> #include <net/if_arp.h> #include <sys/socket.h>  #include <netinet/in.h>  #include <arpa/inet.h>   #include <netinet/ip.h>  #include <netdb.h>  #include <netinet/tcp.h>  #include <netinet/udp.h> #include <signal.h>  #include <net/if.h>  #include <sys/ioctl.h>  #include <sys/stat.h>  #include <fcntl.h>  #include <linux/if_ether.h> #include <net/ethernet.h> #include <linux/igmp.h> #include <netinet/tcp.h>     /* 全局变量结构的结构体原型 - 包含要记录的任何全局信息 */ struct global_info {     unsigned int bytes;     /* 网卡接收的总字节数     */     unsigned int packet_num;        /* 网卡接受的帧的总数量   */           unsigned int packet_arp;        /* 接收到的arp包的数量    */     unsigned int packet_rarp;       /* 接收到的rarp包的数量   */       unsigned int packet_ip;     /* 接收到的ip包的数量     */     unsigned int packet_icmp;   /* 接收到的icmp包的数量   */     unsigned int packet_igmp;   /* 接收到的igmp包的数量   */       unsigned int packet_tcp;    /* 接收到的tcp包的数量    */     unsigned int packet_udp;    /* 接收到的udp包的数量    */           int print_flag_frame;       /* 是否打印帧头信息标志, 1表示打印, 0表示不打印 */     int print_flag_arp;     /* 是否打印arp头信息标志  */     int print_flag_ip;      /* 是否打印ip头信息标志   */     int print_flag_rarp;        /* 是否打印rarp头信息标志 */     int print_flag_tcp;     /* 是否打印tcp头信息标志  */     int print_flag_udp;     /* 是否打印udp头信息标志  */     int print_flag_icmp;        /* 是否打印icmp头信息标志 */     int print_flag_igmp;        /* 是否打印igmp头信息标志 */ };     /* 定义一个全局变量，用于存储全局信息 */ struct global_info global;   struct ip_pair {     unsigned int source_ip;     unsigned int dest_ip;     unsigned int count; };   /* 定义一个用于存储ip对的结构体数组 */ struct ip_pair ip_pair[10000];   /* 一个用于初始化全局信息的函数 */ void init_global( struct global_info  * var );   /* 一个用于打印全局信息的函数   */ void print_global( struct global_info var );   /* 打印一个错误,并退出       */ void error_and_exit( char * msg, int exit_code );   /* 设置网卡成混杂模式            */ int set_card_promisc( char * interface_name, int sock );   /* 把mac地址转换一个字符串      */ void mac_to_str( char * buf, char * mac_buf );   /* 用于打印帮助信息         */ void help( void );   /* 截获网卡帧数据,并进行数据分用*/ void do_frame( int sockfd );      /* 处理ip层数据              */ void do_ip( char * data );   /* 打印ip头信息          */ void print_ip( struct iphdr * );   /* 处理arp层数据        */ void do_arp( char * data );   /* 打印arp头信息            */ void print_arp( struct arphdr * );   /* 处理rarp数据            */ void do_rarp( char * data );     /* 处理tcp层数据            */ void do_tcp( char * data );   /* 打印tcp层头信息           */ void print_tcp( struct tcphdr * );   /* 处理udp层数据            */ void do_udp( char * data );   /* 打印udp层头信息           */ void print_udp( struct udphdr * );     /* 处理icmp层数据           */ void do_icmp( char * data );   /* 打印icmp头信息           */ void print_icmp( struct icmphdr * );   /* 处理igmp层数据           */ void do_igmp( char * data );   /* 打印igmp头信息           */ void print_igmp( struct igmphdr * );       /* 初始化一个全局结构体         */ void init_global( struct global_info  * var ) {     var->bytes = 0;     var->packet_num = 0;           var->packet_arp = 0;     var->packet_rarp = 0;     var->packet_ip = 0;     var->packet_icmp = 0;     var->packet_igmp = 0;     var->packet_tcp = 0;     var->packet_udp = 0;           var->print_flag_frame = 0;     var->print_flag_arp = 0;     var->print_flag_ip = 0;     var->print_flag_rarp = 0;     var->print_flag_tcp = 0;     var->print_flag_udp = 0;     var->print_flag_icmp = 0;     var->print_flag_igmp = 0; }   /* 一个用于打印全局信息的函数  */ void print_global( struct global_info var ) {     printf("\n\n********** 全局信息 *****************\n\n");     printf("总共接收字节数: %d kbytes.\n", var.bytes / 1024 );     printf("总共接受包数量: %d\n\n", var.packet_num );           if( var.packet_arp ) printf("接收 arp 包数量: %d\n", var.packet_arp );     if( var.packet_rarp) printf("接收 rarp 包数量: %d\n", var.packet_rarp );     if( var.packet_ip )  printf("接收 ip 包数量: %d\n", var.packet_ip );     if( var.packet_icmp) printf("接收 icmp 包数量: %d\n", var.packet_icmp );     if( var.packet_igmp) printf("接收 igmp 包数量: %d\n", var.packet_igmp );     if( var.packet_tcp ) printf("接收 tcp 包数量: %d\n", var.packet_tcp );     if( var.packet_udp ) printf("接收 udp 包数量: %d\n", var.packet_udp );           printf("\n"); }   /* 用于处理当下按ctrl-c时的处理函数 */ void sig_int( int sig ) {     print_global( global );           int i;           /*     for( i=0; i<global.packet_ip; i++ ){         printf("%15s ==>> ", inet_ntoa( *(struct in_addr *)( &ip_pair[i].source_ip ) ) );         printf("%15s \n", inet_ntoa( *(struct in_addr *)( &ip_pair[i].dest_ip ) ));     }     */       exit( 0 ); }   /* 打印错误信息，并退出            */ void error_and_exit( char * msg, int exit_code )  {      herror( msg );      exit( exit_code );  }    /* 设置网卡模式成混帐模式,这样的话可以截获以太网帧数据 */ int set_card_promisc( char * interface_name, int sock )  {      /* 用于套接口ioctl的接口请求结构体   */     struct ifreq ifr;                       /* 复制网卡名称进入请求结构体的名称元素 */     strncpy(ifr.ifr_name, interface_name ,strlen( interface_name )+1);        /* 通过ioctl获得相应信息            */     if((ioctl(sock, SIOCGIFFLAGS, &ifr) == -1)) {                   error_and_exit("ioctl", 2);      }        /* 设置网卡模式标志为混杂模式           */         ifr.ifr_flags |= IFF_PROMISC;                         /* 通过ioctl把参数传递给网卡         */      if(ioctl(sock, SIOCSIFFLAGS, &ifr) == -1 )                    error_and_exit("ioctl", 3);  }    /* 把mac地址转换成字符串 */ void mac_to_str( char * buf, char * mac_buf ) {     sprintf( mac_buf, "%02x:%02x:%02x:%02x:%02x:%02x",(unsigned char) *buf, (unsigned char)(*(buf+1)),                     (unsigned char)(*(buf+2)), (unsigned char)(*(buf+3)),                     (unsigned char)(*(buf+4)), (unsigned char)(*(buf+5)));     mac_buf[17] = 0; }   void help( void ) {     printf("Usage: capture [-h] [协议名称 ...].\n");     printf("默认情况: 打印所有包信息.\n"); }   void print_udp( struct udphdr * pudp ) {     printf("==================== udp 头信息 ======================\n");     printf("16位源端口号  : %d\n", ntohs( pudp->source ) );     printf("16位目的端口号:   %d\n", ntohs( pudp->dest ) );     printf("16位udp长度: %d\n", ntohs( pudp->len ) );     printf("16位udp校验和: %d\n", ntohs( pudp->check ) );     if( ntohs( pudp->len ) != sizeof(struct udphdr ) && ntohs( pudp->len ) < 20 ){         char * data = ( char * )pudp + sizeof( struct udphdr );         printf("UDP数据: %s\n", data );     } }   void do_udp( char * data ) {     global.packet_udp ++;       struct udphdr * pudp = ( struct udphdr * )data;     if( global.print_flag_udp )         print_udp( pudp );  }     void print_tcp( struct tcphdr * ptcp ) {     printf("==================== tcp 头信息 =====================\n");     printf("源端口号  : %d\n", ntohs( ptcp->source ) );     printf("目的端口号: %d\n", ntohs( ptcp->dest ) );     printf("32位序列号  : %u\n", ntohl( ptcp->seq ) );     printf("32位确认序号: %u\n", ntohl( ptcp->ack_seq ) );     printf("首部长度: %d\n", ptcp->doff * 4 );     printf("6个标志位: \n");     printf("    紧急指针 urg : %d\n", ptcp->urg );     printf("    确认序号位 ack : %d\n", ptcp->ack );     printf("    接受方尽快将报文交给应用层 psh : %d\n", ptcp->psh );     printf("    重建连接 rst : %d\n", ptcp->rst );     printf("    用来发起连接的同步序号 syn : %d\n", ptcp->syn );     printf("    发送端完成任务 fin : %d\n", ptcp->fin );     printf("16位窗口大小: %d\n", ntohs( ptcp->window ) );     printf("16位校验和: %d\n", ntohs( ptcp->check ) );     printf("16位紧急指针: %d\n", ntohs( ptcp->urg_ptr ) );               if( ptcp->doff * 4 == 20 ){         printf("选项数据: 没有\n");     } else {         printf("选项数据: %d 字节\n", ptcp->doff * 4 - 20 );     }           char * data = ( char * )ptcp;     data += ptcp->doff * 4;     printf("数据长度: %d 字节\n", strlen(data) );     if( strlen(data) < 10 )printf("数据: %s\n", data ); }   void do_tcp( char * data ) {     global.packet_tcp ++;       struct tcphdr * ptcp;     ptcp = ( struct tcphdr * )data;           if( global.print_flag_tcp )         print_tcp( ptcp ); }   void print_igmp( struct igmphdr * pigmp ) {     printf("====================  igmp 包信息 ==========================\n");     printf("igmp 版本: %d\n", pigmp->type & 15 );     printf("igmp 类型: %d\n", pigmp->type >> 4 );     printf("igmp 码: %d\n", pigmp->code );     printf("igmp 校验和: %d\n", ntohs( pigmp->csum ) );     printf("igmp 组地址: %d\n", ntohl( pigmp->group ) ); }   void do_igmp( char * data ) {     global.packet_igmp ++;     struct igmphdr * pigmp = ( struct igmphdr * ) data;           if( global.print_flag_igmp )         print_igmp( pigmp ); }   void print_icmp( struct icmphdr * picmp ) {     printf("==================== icmp 包信息 ===========================\n");           printf("消息类型: %d ", picmp->type );         switch( picmp->type ){             case ICMP_ECHOREPLY:                 printf("Ping的回显应答\n");                 break;             case ICMP_DEST_UNREACH:                     printf("目的不可达\n");                 break;             case ICMP_SOURCE_QUENCH:                 printf("源端被关闭\n");                 break;             case ICMP_REDIRECT:                 printf("重定相\n");                  break;             case ICMP_ECHO:                 printf("ping的回显请求\n");                    break;             case ICMP_TIME_EXCEEDED:                 printf("超时\n");                 break;             case ICMP_PARAMETERPROB:                 printf("参数问题\n");                 break;             case ICMP_TIMESTAMP:                 printf("时间戳请求\n");                   break;             case ICMP_TIMESTAMPREPLY:                 printf("时间戳应答\n");                   break;             case ICMP_INFO_REQUEST:                 printf("信息请求\n");                  break;             case ICMP_INFO_REPLY:                 printf("信息应答\n");                 break;             case ICMP_ADDRESS:                 printf("地址掩码请求\n");                 break;             case ICMP_ADDRESSREPLY:                 printf("地址掩码应答\n");                 break;             default:                 printf("未知消息类型\n");                 break;         }     printf("消息类型的子选项: %d ", picmp->code );         switch( picmp->type ){             case ICMP_ECHOREPLY:                 printf("Ping的回显应答\n");                 break;             case ICMP_DEST_UNREACH:                 switch( picmp->type ){                     case ICMP_NET_UNREACH:                         printf("网络不可到达\n");                         break;                     case ICMP_HOST_UNREACH:                         printf("主机不可到达\n");                          break;                     case  ICMP_PROT_UNREACH:                         printf("协议不可到达\n");                         break;                      case  ICMP_PORT_UNREACH:                         printf("端口不可到达\n");                         break;                     case  ICMP_FRAG_NEEDED:                         printf("需要进行分片,但是又设置不分片位\n");                         break;                     case  ICMP_SR_FAILED:                         printf("源站选路失败\n");                         break;                     case  ICMP_NET_UNKNOWN:                         printf("目的网络不认识\n");                         break;                     case  ICMP_HOST_UNKNOWN:                         printf("目的主机不认识\n");                         break;                     case  ICMP_HOST_ISOLATED:                         printf("源主机北隔离\n");                         break;                     case  ICMP_NET_ANO:                         printf("目的网络被强制禁止\n");                         break;                     case  ICMP_HOST_ANO:                         printf("目的主机被强制禁止\n");                         break;                     case  ICMP_NET_UNR_TOS:                         printf("由于服务类型TOS,网络不可到达\n");                         break;                     case  ICMP_HOST_UNR_TOS:                         printf("由于服务类型TOS,主机不可到达\n");                         break;                     case  ICMP_PKT_FILTERED:                         printf("由于过滤,通信被强制禁止\n");                         break;                     case  ICMP_PREC_VIOLATION:                         printf("主机越权\n");                         break;                     case  ICMP_PREC_CUTOFF:                         printf("优先权中止生效\n");                         break;                     default:                         printf("未知代码\n");                         break;                   }                 break;             case ICMP_SOURCE_QUENCH:                 printf("源端被关闭\n");                 break;             case ICMP_REDIRECT:                 switch( picmp->type ){                     case ICMP_REDIR_NET:                         printf("对网络重定向\n");                         break;                     case ICMP_REDIR_HOST:                         printf("对主机重定向\n");                           break;                     case ICMP_REDIR_NETTOS:                         printf("对服务类型和网络重定向\n");                          break;                     case ICMP_REDIR_HOSTTOS:                         printf("对服务类型和主机重定向\n");                         break;                     defalut:                         printf("未知代码\n");                         break;                 }                 break;             case ICMP_ECHO:                 printf("ping的回显请求\n");                    break;             case ICMP_TIME_EXCEEDED:                 switch( picmp->type ){                     case ICMP_EXC_TTL:                         printf("在传输期间生存时间为0\n");                         break;                     case ICMP_EXC_FRAGTIME:                         printf("在数据组装期间生存时间为0\n");                         break;                     default:                         printf("未知代码\n");                         break;                 }                 break;             case ICMP_PARAMETERPROB:                 switch( picmp->type ){                     case 0:                         printf("IP首部错误(包括各种差错)\n");                         break;                     case 1:                         printf("缺少必须的选项\n");                         break;                     default:                         printf("原因未知\n");                         break;                 }                 break;             case ICMP_TIMESTAMP:                 printf("时间戳请求\n");                   break;             case ICMP_TIMESTAMPREPLY:                 printf("时间戳应答\n");                   break;             case ICMP_INFO_REQUEST:                 printf("信息请求\n");                  break;             case ICMP_INFO_REPLY:                 printf("信息应答\n");                 break;             case ICMP_ADDRESS:                 printf("地址掩码请求\n");                 break;             case ICMP_ADDRESSREPLY:                 printf("地址掩码应答\n");                 break;             default:                 printf("未知消息类型\n");                 break;         }       printf("校验和: %d\n", ntohs(picmp->checksum) ); }   void do_icmp( char * data ) {     global.packet_icmp ++;       struct icmphdr * picmp = ( struct icmphdr * ) data;           if( global.print_flag_icmp )         print_icmp( picmp ); }   void print_ip( struct iphdr * iph ) {     printf("=============== ip 头信息 ===============\n");     printf("IP 首部长度:%d\n", iph->ihl * 4 );     printf("IP 版本    :%d\n", iph->version );     printf("服务类型(tos): %d\n", iph->tos );     printf("总长度字节: %d\n", ntohs(iph->tot_len) );     printf("16位标识: %d\n", ntohs(iph->id) );     printf("frag off: %d\n", ntohs(iph->frag_off) );     printf("8位生存事件: %d\n", iph->ttl );     printf("8位协议: %d\n", iph->protocol );     printf("16位首部校验和: %d\n", ntohs(iph->check) );     printf("32位源IP地址  : %s\n", inet_ntoa( *(struct in_addr *)(&iph->saddr)) );     printf("32位目的IP地址: %s\n", inet_ntoa( *(struct in_addr *)(&iph->daddr)) );           }   void ip_count( struct iphdr * iph ) {     ip_pair[ global.packet_ip - 1 ].source_ip = iph->saddr;     ip_pair[ global.packet_ip - 1 ].dest_ip = iph->daddr; }   void do_ip( char * data ) {     global.packet_ip ++;       struct iphdr *pip;             pip = ( struct iphdr * ) data;    /* pip = point to ip layer */     if( global.print_flag_ip )         print_ip( pip );           ip_count( pip );           char * pdata = data + pip->ihl * 4;           switch( pip->protocol ){         case IPPROTO_ICMP:             do_icmp( pdata );             break;         case IPPROTO_IGMP:             do_igmp( pdata );             break;         case IPPROTO_TCP:             do_tcp( pdata );             break;         case IPPROTO_UDP:             do_udp( pdata );             break;         default:             printf("IP: 未知其上层协议.\n");             break;     } }   void print_arp( struct arphdr * parp ) {       printf("硬件类型: %d ", ntohs(parp->ar_hrd) );         switch( ntohs( parp->ar_hrd ) ){             case ARPHRD_ETHER:                 printf("Ethernet 10/100Mbps.\n");                   break;             case ARPHRD_EETHER:                 printf("Experimental Ethernet.\n");                 break;             case ARPHRD_AX25:                 printf("AX.25 Level 2.\n");                 break;             case ARPHRD_PRONET:                 printf("PROnet token ring.\n");                 break;             case ARPHRD_IEEE802:                 printf("IEEE 802.2 Ethernet/TR/TB.\n");                 break;             case ARPHRD_APPLETLK:                 printf("APPLEtalk.\n");                 break;             case ARPHRD_ATM:                    printf("ATM.\n");                                       break;             case ARPHRD_IEEE1394:                 printf("IEEE 1394 IPv4 .\n");                 break;             default:                 printf("Unknow.\n");                 break;         }     printf("映射的协议地址类型: %d ", ntohs(parp->ar_pro) );         switch( ntohs(parp->ar_pro) ){             case ETHERTYPE_IP:                 printf("IP.\n");                 break;             default:                 printf("error.\n");                 break;         }     printf("硬件地址长度: %d\n", parp->ar_hln );     printf("协议地址长度: %d\n", parp->ar_pln );     printf("操作码: %d ", ntohs(parp->ar_op) );         switch( ntohs(parp->ar_op) ){             case ARPOP_REQUEST:                 printf("ARP 请求.\n");                 break;             case ARPOP_REPLY:                   printf("ARP 应答.\n");                 break;             case ARPOP_RREQUEST:                 printf("RARP 请求.\n");                 break;             case ARPOP_RREPLY:                 printf("RARP 应答.\n");                 break;             case ARPOP_InREQUEST:                 printf("InARP 请求.\n");                 break;             case ARPOP_InREPLY:                 printf("InARP 应答.\n");                          break;             case ARPOP_NAK:                 printf("(ATM)ARP NAK.\n");                 break;             default:                 printf("arp 操作码错误.\n");                 break;         }           char * addr = (char*)(parp + 1);     char buf[18];     mac_to_str( addr, buf );     printf("发送端以太网地址: %s\n", buf );     printf("发送端IP地址:     %s\n", inet_ntoa( *(struct in_addr *)(addr+6) ));     mac_to_str( addr+10, buf );     printf("目的以太网地址: %s\n", buf );     printf("目的IP地址:     %s\n", inet_ntoa( *(struct in_addr *)(addr+16) )); }   void do_arp( char * data ) {     global.packet_arp ++;       struct arphdr * parp;     parp = ( struct arphdr * ) data;           if( global.print_flag_arp ) {         printf("============= arp 头信息 ==============\n");         print_arp( parp );     } }   void do_rarp( char * data ) {     global.packet_rarp ++;         struct arphdr * parp;     parp = ( struct arphdr * ) data;           if( global.print_flag_rarp ){         printf("============= rarp 头信息 =============\n");         print_arp( parp );     } }   /* 打印以太网帧的包头信息 */ void print_frame( struct ether_header * peth ) {     /* 定义一个数组，用于存储把mac地址转换成字符串后的字符串 */     char buf[ 18 ];       printf("\n==================================   第 %d 个包  =======================================\n\n", global.packet_num );     printf("==== 以太网帧信息 =====\n");     char * shost = peth->ether_shost;     mac_to_str( shost, buf );           printf("源以太网地址:  %s\n", buf );           char * dhost = peth->ether_dhost;     mac_to_str( dhost, buf );     printf("目的以太网地址:%s\n", buf ); }     /* 用于从网卡接受一帧数据,同时根据以太网协议字段传递数据给相应的上层协议处理 */ void do_frame( int sock ) {     /* 用于存储一帧数据         */     char frame_buf[ 2000 ];           /* 清空帧数据缓冲区     */     bzero( frame_buf, sizeof(frame_buf) );       int len = sizeof( frame_buf );           /* 用于存储接受字节数       */     int recv_num;       /* 用于存储发送方的地址信息 */     struct sockaddr_in addr;       /* 从网卡接收一帧数据       */         recv_num = recvfrom( sock, (char *)frame_buf, sizeof( frame_buf ), 0, ( struct sockaddr * )&addr, &len );        /* 所接收的包的总数自加1    */     global.packet_num ++;       /* 从网卡接收的字节总数     */     global.bytes += recv_num;       /* 打印接收的包是第几个包   */     //printf("此帧数据长度: %d\n", recv_num );           /* 定义一个用于指向以太网帧的指针 (这里我们只考虑最常见的以太网帧的情况) */     struct ether_header * peth;       /* 让以太网头指针指向从网卡接受到的帧的数据的开头 */         peth = (struct ether_header *)frame_buf;       /* 传递以太网帧首地址给打印以太网帧信息的打印函数 */     if( global.print_flag_frame )         print_frame( peth );       /* 定义一个数据指针,用于指向以太网帧的数据部分    */     char * pdata;       /* 让 pdata 指向以太网帧的数据部分                */     pdata = frame_buf + sizeof( struct ether_header );       /* 根据以太网帧的协议字段进行数据分用 － 也就是进行数据拆封，根据协议字段调用相应层的处理函数 */         switch( ntohs( peth->ether_type ) ){             case ETHERTYPE_PUP:             break;         case ETHERTYPE_IP:             do_ip( pdata );             break;         case ETHERTYPE_ARP:             do_arp( pdata );             break;         case ETHERTYPE_REVARP:             do_rarp( pdata );             break;         default:             printf("Unkonw ethernet type  %d %x.\n", ntohs(peth->ether_type), ntohs(peth->ether_type) );             break;        } }     /* 主函数, 处理命令行输入, 设置好全局变量, 并调用接受和处理帧的函数 */   int main( int argc, char ** argv )  {      /* 用于存储套接口文件描述符 */     int sockfd;       /* 初始化全局变量    */     init_global( &global );       if( argc == 1 ) {               /* 表示打印所有包头信息 */         global.print_flag_frame = 1;         global.print_flag_arp = 1;         global.print_flag_ip = 1;         global.print_flag_rarp = 1;         global.print_flag_tcp = 1;         global.print_flag_udp = 1;         global.print_flag_icmp = 1;         global.print_flag_igmp = 1;     } else {               /* 帮助 或者 通过指定协议名称只打印某层些协议 */         if( !strcasecmp( argv[1], "-h" ) ){             help();             exit( 0 );         } else {             int i;             for( i=1; i < argc; i++ ){                 if( !strcasecmp( argv[i], "frame" ) )                     global.print_flag_frame = 1;                 else if( !strcasecmp( argv[i], "arp" ) )                     global.print_flag_arp = 1;                 else if( !strcasecmp( argv[i], "rarp" ) )                     global.print_flag_rarp = 1;                 else if( !strcasecmp( argv[i], "ip" ) )                     global.print_flag_ip = 1;                 else if( !strcasecmp( argv[i], "tcp" ) )                     global.print_flag_tcp = 1;                 else if( !strcasecmp( argv[i], "udp" ) )                     global.print_flag_udp = 1;                 else if( !strcasecmp( argv[i], "icmp" ) )                     global.print_flag_icmp = 1;                 else if( !strcasecmp( argv[i], "igmp" ) )                     global.print_flag_igmp = 1;             }         }     }           /* 通过协议族AF_PACKET类信SOCK_RAW, 类型SOCK_RAW创建一个用于可以接受网卡帧数据的套接口,同时返回套就口文件描述符 */     if( (sockfd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL)) ) == -1 )             error_and_exit( "socket", 1 );  /* 如果发生错误，返回错误值, 并退出 */             /* 设定网卡eth0成混杂模式 */     set_card_promisc( "eth0", sockfd );       /* 设定信号处理函数, 下面是设置当我们按下ctrl-c时所调用的处理函数 */       signal( SIGINT, sig_int );       /* 无限循环接收以太网卡数据帧, 并进行数据分用,直到你按下ctrl-c */     while( 1 ){         do_frame( sockfd );     }        return 0; }

　　参考资料：

http://www.cnblogs.com/rollenholt/articles/2585432.html

http://www.binarytides.com/blog/c-packet-sniffer-code-with-libpcap-and-linux-sockets-bsd/

http://www.binarytides.com/blog/packet-sniffer-code-in-c-using-linux-sockets-bsd-part-2/

http://www.binarytides.com/blog/packet-sniffer-code-in-c-using-linux-sockets-bsd/