mac-address

after ARP protocol in a frame, there are many 0 bytes. Does anyone know the reason for the existence of these 0 bytes? Check the Ethernet II accordion, all the 0 are labelled as padding. Ethernet requires that all packets be at least 60 bytes long (64 bytes if you include the Frame Check Sequence at the end), so if a packet is less than 60 bytes long (including the 14-byte Ethernet header), additional padding bytes have to be added to the end of the packet. (Those padding bytes will not show up on packets sent by the machine running Wireshark; the padding is added by the Ethernet hardware, and

I am using the following code to retrieve all MAC addresses for current computer: ifreq ifr; ifconf ifc; char buf[1024]; int sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); if (sock == -1) { ... }; ifc.ifc_len = sizeof(buf); ifc.ifc_buf = buf; if (ioctl(sock, SIOCGIFCONF, &ifc) == -1) { ... } ifreq *it = ifc.ifc_req; const ifreq* const end = it + (ifc.ifc_len / sizeof(ifreq)); for (; it != end; ++it) { strcpy(ifr.ifr_name, it->ifr_name); if (ioctl(sock, SIOCGIFFLAGS, &ifr) == 0) { if (!(ifr.ifr_flags & IFF_LOOPBACK)) { if (ioctl(sock, SIOCGIFHWADDR, &ifr) == 0) { unsigned char mac_address[6];

I hope this was the right place to post this, sorry if it isn't. Also, I know next to nothing about networks. I'm trying to allocate bandwidth to different devices on my Linksys E1200 router. When I check my computer's MAC address, it comes back as 74:E5:0B:10:01:04 . I turned off everything in my apartment besides my xbox and notebook, and under the DHCP client table under my router settings I see the xbox along with " Owner-PC " and a MAC address of 00:21:6B:10:A8:6E . Is this my computer, and if so, why are there different MAC addresses? MAC Addresses are NIC specific.. Each Network

Os:REDHAT LINUX Linux manage: 2.6.18.8-1 # Is this possible to read MAC address form NIC directly ? I have below code but it just read from above layer but not the card itself !!! I'm trying to figure out how to find the original MAC address of an ethernet NIC on my linux box. I understand how to find the current MAC address using ifconfig, but if the address has been changed, say by using 'ifconfig eth0 hw ether uu:vv:ww:yy:xx:zz' ,or I set "permanent" it using vi /etc/sysconfig/network-scripts/ifcfg-eth0 .this file...I can successfully UP it in REBOOT also. how do I find the original? There

I want to ping a known MAC address, I tried to use nmap: sudo nmap -sP 192.168.15.1/24 | grep 20:64:32:3F:B1:A9 But in this case its ping all the 255 IP address (from 192.168.15.1 to 192.168.15.255) until get my MAC address, and that take a long time about 4 sec.! any idea please? The only way to make it faster is to test if the mac address is already into your arp table #!/bin/bash # extract ip from local arp table ip=$(arp | grep 20:64:32:3F:B1:A9 | awk ' { print $1 } ') # found an ip tied to the mac address? if [ ! -z $ip ]; then # if found, do you want to ping it? ping $ip else echo "Not