函数名称： pcap_t *pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
函数功能：获得用于捕获网络数据包的数据包捕获描述字。
参数说明：device参数为指定打开的网络设备名。snaplen参数定义捕获数据的最大字节数。promisc指定是否将网络接口置于混杂模式。toms参数指*定超时时间（毫秒）。ebuf参数则仅在pcapopen_live()函数出错返回NULL时用于传递错误消息。

/*************************************************************************
        > File Name : pcap_example.c
        > Author : TL Song
        > EMail : songtianlun@frytea.com
        > Created Time : Thu Feb 18 18:57:20 2021
     ************************************************************************/
    #include <stdio.h>
    #include <string.h>
    #include <pthread.h>
    #include <pcap.h>
     
    #define RECV_DEVICE      "ens3"
    #define RECV_DEVICE_SEND "docker0"
    #define RECV_FILTER      "arp or icmp"
     
    #define dPrint(fmt, ...) do{fprintf(stderr, "[%s:%d] " fmt "\r\n", __FUNCTION__, __LINE__, ##__VA_ARGS__);}while(0)
     
    int main()
    {
        char err_buf[PCAP_ERRBUF_SIZE];
        struct bpf_program fp_recv;      /* The compiled filter expression */
        char filter_recv[] = RECV_FILTER;  /* The filter expression (filter 53 port)*/
        pcap_t *handle_recv;
        pcap_t *handle_recv_send;
        bpf_u_int32 mask_recv;       /* The netmask of our sniffing device */
        bpf_u_int32 net_recv;        /* The IP of our sniffing device */
        u_char *pkt_data = NULL;
        int rst;
        struct pcap_pkthdr header;
        struct pcap_pkthdr *p_header = &header;
     
        printf("Recv Device: %s\n", RECV_DEVICE);
     
        /*Step1, Open the session in promiscuous mode*/
        handle_recv = pcap_open_live(RECV_DEVICE, BUFSIZ, 1, 1, err_buf);
        if (handle_recv == NULL) {
            fprintf(stderr, "Couldn't open device %s: %s\n", RECV_DEVICE, err_buf);
            return 0;
        }
     
        handle_recv_send = pcap_open_live(RECV_DEVICE_SEND, BUFSIZ, 1, 1, err_buf);
        if (handle_recv_send == NULL) {
            printf("Couldn't open device %s: %s\n", RECV_DEVICE_SEND, err_buf);
            return 0;
        }
     
        /*Step2, get network mask*/
        if (pcap_lookupnet(RECV_DEVICE, &net_recv, &mask_recv, err_buf) == -1) {
            fprintf(stderr, "Can't get netmask for device %s\n", RECV_DEVICE);
            net_recv = 0;
            mask_recv = 0;
        }
     
        /* Step3, Compile and apply the filter */
        if (pcap_compile(handle_recv, &fp_recv, filter_recv, 0, net_recv) == -1) {
            fprintf(stderr, "Couldn't parse filter %s: %s\n", filter_recv, pcap_geterr(handle_recv));
            return 0;
        }
        if (pcap_setfilter(handle_recv, &fp_recv) == -1) {
            fprintf(stderr, "Couldn't install filter %s: %s\n", filter_recv, pcap_geterr(handle_recv));
            return 0;
        }
     
        /* Step4, get frame. */
        while(1){
            pkt_data = (unsigned char * )pcap_next(handle_recv, p_header);
            rst = pcap_sendpacket(handle_recv_send, pkt_data, p_header->caplen);
            printf("Send to %s ret : %d\n", RECV_DEVICE_SEND, rst);
        }
     
        /* Step5, cleanup */
        pcap_freecode(&fp_recv);
        pcap_close(handle_recv);
        pcap_close(handle_recv_send);
        dPrint("Capture complete.");
        return 0;
    }