c - 套接字权限ubuntu

Question

您好，我是 Linux 新手，有一个与套接字相关的项目。我面临的问题是，当我使用输入 eth0 for interface 和我的路由器的 ip 地址运行代码时，即 ./mycode eth0 192.168.1.1 报错

You don't have permission to capture on that device (socket: Operation not permitted)

我从链接中获取的代码是:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pcap.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <net/ethernet.h>
#include <netinet/if_ether.h>
#include <sys/ioctl.h>

int main(int argc,const char* argv[]) {
    // Get interface name and target IP address from command line.
    if (argc<2) {
        fprintf(stderr,"usage: send_arp <interface> <ipv4-address>\n");
        exit(1);
    }
    const char* if_name=argv[1];
    const char* target_ip_string=argv[2];

    // Construct Ethernet header (except for source MAC address).
    // (Destination set to broadcast address, FF:FF:FF:FF:FF:FF.)
    struct ether_header header;
    header.ether_type=htons(ETH_P_ARP);
    memset(header.ether_dhost,0xff,sizeof(header.ether_dhost));

    // Construct ARP request (except for MAC and IP addresses).
    struct ether_arp req;
    req.arp_hrd=htons(ARPHRD_ETHER);
    req.arp_pro=htons(ETH_P_IP);
    req.arp_hln=ETHER_ADDR_LEN;
    req.arp_pln=sizeof(in_addr_t);
    req.arp_op=htons(ARPOP_REQUEST);
    memset(&req.arp_tha,0,sizeof(req.arp_tha));

    // Convert target IP address from string, copy into ARP request.
    struct in_addr target_ip_addr={0};
    if (!inet_aton(target_ip_string,&target_ip_addr)) {
       fprintf(stderr,"%s is not a valid IP address",target_ip_string);
       exit(1);
    }
    memcpy(&req.arp_tpa,&target_ip_addr.s_addr,sizeof(req.arp_tpa));

    // Write the interface name to an ifreq structure,
    // for obtaining the source MAC and IP addresses.
    struct ifreq ifr;
    size_t if_name_len=strlen(if_name);
    if (if_name_len<sizeof(ifr.ifr_name)) {
        memcpy(ifr.ifr_name,if_name,if_name_len);
        ifr.ifr_name[if_name_len]=0;
    } else {
        fprintf(stderr,"interface name is too long");
        exit(1);
    }

    // Open an IPv4-family socket for use when calling ioctl.
    int fd=socket(AF_INET,SOCK_DGRAM,0);
    if (fd==-1) {
        perror(0);
        exit(1);
    }

    // Obtain the source IP address, copy into ARP request
    if (ioctl(fd,SIOCGIFADDR,&ifr)==-1) {
        perror(0);
        close(fd);
        exit(1);
    }
    struct sockaddr_in* source_ip_addr = (struct sockaddr_in*)&ifr.ifr_addr;
    memcpy(&req.arp_spa,&source_ip_addr->sin_addr.s_addr,sizeof(req.arp_spa));

    // Obtain the source MAC address, copy into Ethernet header and ARP request.
    if (ioctl(fd,SIOCGIFHWADDR,&ifr)==-1) {
        perror(0);
        close(fd);
        exit(1);
    }
    if (ifr.ifr_hwaddr.sa_family!=ARPHRD_ETHER) {
        fprintf(stderr,"not an Ethernet interface");
        close(fd);
        exit(1);
    }
    const unsigned char* source_mac_addr=(unsigned char*)ifr.ifr_hwaddr.sa_data;
    memcpy(header.ether_shost,source_mac_addr,sizeof(header.ether_shost));
    memcpy(&req.arp_sha,source_mac_addr,sizeof(req.arp_sha));
    close(fd);

    // Combine the Ethernet header and ARP request into a contiguous block.
    unsigned char frame[sizeof(struct ether_header)+sizeof(struct ether_arp)];
    memcpy(frame,&header,sizeof(struct ether_header));
    memcpy(frame+sizeof(struct ether_header),&req,sizeof(struct ether_arp));

    // Open a PCAP packet capture descriptor for the specified interface.
    char pcap_errbuf[PCAP_ERRBUF_SIZE];
    pcap_errbuf[0]='\0';
    pcap_t* pcap=pcap_open_live(if_name,96,0,0,pcap_errbuf);
    if (pcap_errbuf[0]!='\0') {
        fprintf(stderr,"%s\n",pcap_errbuf);
    }
    if (!pcap) {
        exit(1);
    }

    // Write the Ethernet frame to the interface.
    if (pcap_inject(pcap,frame,sizeof(frame))==-1) {
        pcap_perror(pcap,0);
        pcap_close(pcap);
        exit(1);
    }

    // Close the PCAP descriptor.
    pcap_close(pcap);
    return 0;
}

Answer 1

您需要 root 权限才能执行此操作。尝试以 root 身份运行您的程序。