Hallo everybody,
i write a small program to read from the arp table. It
functions but the output is corrupted.
I would want to know why?
The output of my program:
[root@heghta fleetnet]# ./arp
00 ffffffe0 2b 6f 1c 00
The output of the well-know routine arp:
[root@heghta fleetnet]# arp -a
pern.fokus.gmd.de (193.175.135.3) at 08:00:20:8F:7C:50
[ether] on eth0
buran.fokus.gmd.de (193.175.135.1) at
00:E0:2B:6F:1C:00 [ether] on eth0
The program:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <linux/if_arp.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int main(int argc, char **argv)
{
struct sockaddr_in gw_addr;
struct arpreq myreq;
int sockfd, i;
FILE *logfd;
logfd = fopen("logfile", "w+");
memset(&gw_addr, '\0', sizeof(gw_addr));
gw_addr.sin_family = AF_INET;
gw_addr.sin_addr.s_addr =
inet_addr("193.175.135.1");
memset(&myreq, '\0', sizeof(myreq));
memcpy(&myreq.arp_pa, &gw_addr, sizeof(gw_addr));
memcpy(&myreq.arp_dev, "eth0",
sizeof(myreq.arp_dev));
if ((sockfd = socket(AF_INET,SOCK_DGRAM, 0)) < 0) {
perror("socket");
exit(-1);
}
if (ioctl(sockfd,SIOCGARP,(char *)&myreq) < 0) {
perror("ioctl");
exit(-1);
}
for ( i = 0; i < 6; i++)
fprintf(stdout,"%02x%s",myreq.arp_ha.sa_data[i], i
== 5 ?"\n": " ");
return 0;
}
Please try it on your machine and tell me if it
functions well.
Thanks.
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