谁成功使用过SIOCGARP获取过ARP的一个表项？
如题，在 http://www3.amherst.edu/~jwmanly/resnet97/getarp.c 找了个程序：

/*  getarp.c -- This simple program uses an IOCTL socket call to read an entry  */
/*  from the ARP cache of the local machine.  Original source unknown.  */ 
/*  Usage:  getarp <ip-number>   */ 
/*  Example:  getarp  148.85.2.1 */ 
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if_arp.h>

/*  arp_flags and at_flags field values */
#defineATF_INUSE0x01/* entry in use */
#define ATF_COM0x02/* completed entry (enaddr valid) */
#defineATF_PERM0x04/* permanent entry */
#defineATF_PUBL0x08/* publish entry (respond for other host) */
#defineATF_USETRAILERS0x10/* has requested trailers */
#defineATF_PROXY0x20/* Do PROXY arp */

main (int argc, char *argv[]) {

    int s;
    struct arpreq arpreq;
    struct sockaddr_in *sin;
    unsigned char *eap;

    if (argc < 2) exit(0);

    memset(&arpreq, 0, sizeof(arpreq));

    sin = (struct sockaddr_in *) &arpreq.arp_pa;
    sin->sin_family = AF_INET;
    sin->sin_addr.s_addr = inet_addr(argv[1]);

    s = socket(AF_INET, SOCK_DGRAM, 0);
    if (s < 0) {
    perror("socket");
    exit(0);
    }
    if (ioctl(s, SIOCGARP, &arpreq) < 0) {
    perror("ioctl");
    exit(0);
    }
    printf("IP address:       %s\n", inet_ntoa(sin->sin_addr));

    if (arpreq.arp_flags & ATF_COM) {
    eap = (unsigned char *) &arpreq.arp_ha.sa_data[0];
    printf("Ethernet address: %02X:%02X:%02X:%02X:%02X:%02X",
        eap[0], eap[1], eap[2], eap[3], eap[4], eap[5]);
    if (arpreq.arp_flags & ATF_PERM) printf(" PERM");
    if (arpreq.arp_flags & ATF_PUBL) printf(" PUBLISHED");
    if (arpreq.arp_flags & ATF_USETRAILERS) printf(" TRAILERS");
    if (arpreq.arp_flags & ATF_PROXY) printf(" PROXY");
    printf("\n");
    } else {
    printf("*** INCOMPLETE ***\n");
    }
    close(s);
    exit(0);
}

用arp -n命令查看我机子的arp表，只有192.168.1.1这个地址，于是我输入 “getarp 192.168.1.1”，可是却返回错误信息 ioctl: No such device。难道是这个程序有问题吗？我想问下谁试过用SIOCGARP成功获取过arp的一个表项?
[解决办法]
你没有写设备选项
在44行上加上strcpy(arpreq.arp->dev, "eth0");试试