2013/1/9 Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>: > On Wed, 9 Jan 2013 09:37:05 -0600 (CST) > Michael Hennebry <hennebry@xxxxxxxxxxxxxxxxxxxxx> wrote: > >> On Wed, 9 Jan 2013, Khemara Lyn wrote: >> >> > Ok, thank you; it's that simple! I've thought about it in a harder way. >> >> Actually, it's even easier. >> NICs come with built-in six-byte MAC adddresses >> that are supposed to be unique. > > They are supposed to be unique *per machine* - you can have two nics on > the same machine with the same MAC although this is rare. > > Alan Alan, please, verify information before dissemination. MAC address assigned to a physical NIC ought to be globally unique. Ethernet frames are sent to MAC address, so two identical addresses present in any broadcast domain would awfully confuse network switches. See e.g. Wikipedia article on MAC https://en.wikipedia.org/wiki/MAC_address. Hardware producers reserve prefixes (first 3 bytes of the address) and are responsible for not manufacturing devices with identical suffixes (last 3 bytes of the address). This should result in globally unique MAC addresses, however I did encounter NICs with identical ones (cheap stuff of unknown and dubious provenance). Khemara, If you use NetworkManager, then it will present you with graphical tool for configuration of NICs and it will handle identification for you. I think it will also generate a UUID for the card and put it into its config file. However, the required and sufficient entry mapping physical device to logical one is HWADDR="xx:yy:zz:aa:bb:cc" line, where xx:yy:zz:aa:bb:cc from this example would be replaced by the real MAC address of your card. UUID line is for NetworkManager's benefit, see also discussion in the list here: https://lists.fedoraproject.org/pipermail/users/2011-May/396591.html. You can determine NIC's MAC address by running ip addr show <device_name> In my KVM F18 guest it produces: $ ip addr show eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 52:54:00:42:1d:c6 brd ff:ff:ff:ff:ff:ff inet 192.168.122.150/24 brd 192.168.122.255 scope global eth0 inet6 fe80::5054:ff:fe42:1dc6/64 scope link valid_lft forever preferred_lft forever $ The card's MAC address is also present in the ifcfg-eth0 file: $ cat ifcfg-eth0 UUID="06693902-df40-49f6-8f0e-c7bac49531c7" NM_CONTROLLED="yes" HWADDR="52:54:00:42:1D:C6" BOOTPROTO="dhcp" DEVICE="eth0" ONBOOT="yes" $ HTH, Paweł -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
