linux tcpdump C++代码

以下是一个简单的 Linux tcpdump C 代码示例：

#include <stdio.h>
#include <stdlib.h>
#include <pcap.h>

void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data);

int main(int argc, char **argv)
{
    pcap_t *adhandle;
    char errbuf[PCAP_ERRBUF_SIZE];
    struct bpf_program fp;
    char filter_exp[] = "port 80";
    bpf_u_int32 mask;
    bpf_u_int32 net;

    // Open the pcap device
    if ((adhandle = pcap_open_live("eth0", 65536, 1, 1000, errbuf)) == NULL)
    {
        fprintf(stderr, "Unable to open the adapter: %s\n", errbuf);
        exit(EXIT_FAILURE);
    }

    // Compile and apply the filter
    if (pcap_compile(adhandle, &fp, filter_exp, 0, net) == -1)
    {
        fprintf(stderr, "Error compiling filter expression\n");
        exit(EXIT_FAILURE);
    }
    if (pcap_setfilter(adhandle, &fp) == -1)
    {
        fprintf(stderr, "Error setting filter\n");
        exit(EXIT_FAILURE);
    }

    // Start capturing packets
    pcap_loop(adhandle, 0, packet_handler, NULL);

    return 0;
}

void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data)
{
    // Process the packet data here
    printf("Packet captured.\n");
}

该代码打开一个名为 "eth0" 的网卡设备，并使用过滤器仅捕获端口号为 80 的流量。在 packet_handler() 函数中，您可以处理捕获到的数据包。在本例中，该函数简单地打印一条消息。