Apple

Hello all,

I’m writing a program on Mac-OS-X to get the Mac address(hardware address) of a host on LAN according to its IP, so I try to use socket with ARP protocol to make it.

But things does not works as I expected:

n when I was constructing the socket on Mac-OS-X , like doing the same thing on Linux:

…

int fd_arp;

if((fd_arp = socket(AF_INET, SOCK_SEQPACKET, htons(0x0806))) < 0)

{

perror("socket error");

goto _ERROR_HANDLER;

}

…

I got the error message on console: ‘socket error: Protocol not supported’. But when I open /etc/protocols, I found that NARP & LARP were declared.

àDoes it means Mac-OS-X socket does not support ARP? Is there any way to make it work?

n When I trying to use the command “arp –a” on the terminal, I can get some of the hosts on the LAN cannot get all of them. Even more, when I use the tool ettercap with the command “./ettercap -l”, ettercap can only list out my own host on LAN but cannot find the others, which confuses me a lot –

àCan anyone here tell me why the arp and ettercap tools cannot work as we expected?

n I’m trying to open device ‘/dev/bpf%d’ and use write()/read() to send/receive ARP packet directly. But I also cannot get the reply packet as I expected.

àCan anyone kindly show me some guideline to make it work in this way or show me other programming ways on Mac-OS-X to get the Mac address of a host by its IP?

Thanks a lot!

Best Regards

Kan Cheng