But now I wonder; in the docs it is stated that ethernet-frames
are passed trough this interface, but when I run something simple
as:
(some code removed)
fdin = open("/dev/tap0", O_RDWR);
for(;;)
{
char buf[1514];
int n;
n = read(fdin, buf, 1514, 0);
if (n>0)
{
struct ethhdr *eth = (struct ethhdr *)buf;
struct iphdr *iph = (struct iphdr
*)(eth+ETH_HLEN);
cnt++;
printf("%03d] ", cnt); disp_mac(eth ->
h_source);
printf(" "); disp_mac(eth -> h_dest);
printf(" %04x|", eth -> h_proto);
if (eth -> h_proto == 0x0800)
{
disp_ipa(iph -> saddr); printf(" ");
disp_ipa(iph -> daddr);
printf(" %02x %d %d", iph -> protocol,
iph -> tot_len, iph -> ttl);
}
printf("\n");
}
}
and I do a ping to some non-existing host on the tap0-device
I get output like:
001] ff:ff:fe:fd:00:00 fb:0f:ff:ff:ff:ff 0000|
002] ff:ff:fe:fd:00:00 fb:0f:ff:ff:ff:ff 0000|
003] ff:ff:fe:fd:00:00 fb:0f:ff:ff:ff:ff 0000|
004] ff:ff:fe:fd:00:00 fb:0f:ff:ff:ff:ff 0000|
I'm not sure about the hardware-address (which looks funny to me - maybe
I have to little endian some things), but that protocol-field:
0x0000?!?!
( the disp_mac-routine:
void disp_mac(unsigned char *adr)
{
int loop;
for(loop=0; loop<ETH_ALEN; loop++)
{
printf("%02x", adr[loop]);
if (loop<(ETH_ALEN-1))
{
printf(":");
}
}
}
)
-- ------------------------------------------------------------ Folkert van Heusden some e-mail addresses: f.v.heusden@ftr.nl, flok99@dds.nl mobile phone: +31-6-22390057
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/