Finding your MAC on Macintosh

/sbin/ifconfig

and read off the "ether" value for en0.

For example:

$ /sbin/ifconfig
lo0: flags=8049 mtu 16384
       inet6 ::1 prefixlen 128
       inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
       inet 127.0.0.1 netmask 0xff000000
gif0: flags=8010 mtu 1280
stf0: flags=0<> mtu 1280
en0: flags=8863 mtu 1500
       inet6 fe80::216:cbff:fecd:3b4d%en0 prefixlen 64 scopeid 0x4
       inet 172.17.102.238 netmask 0xffff0000 broadcast 172.17.255.255
       ether 00:16:cb:cd:3b:4d
       media: autoselect (100baseTX ) status: active
       supported media: autoselect 10baseT/UTP  10baseT/UTP  10baseT/UTP  10baseT/UTP  100baseTX  100baseTX  100baseTX  100baseTX  1000baseT  1000baseT  1000baseT  none
en1: flags=8863 mtu 1500
       ether 00:16:cb:bc:cb:0a
       media: autoselect () status: inactive
       supported media: autoselect
wlt1: flags=41 mtu 1500
fw0: flags=8863 mtu 2030
       lladdr 00:16:cb:ff:fe:de:8e:7a
       media: autoselect  status: inactive
       supported media: autoselect