Date: 4 Jun 1997 00:00:01 EST

  Many thanks to Miguel Sanchez <miguel@oasis.csd.sgi.com> for
  providing the original version of the following discussion, and to
  Dave Olson <olson@sgi.com> for comments. Andrew Cherenson
  <arc@sgi.com> reminded us that all these methods except the first
  apply to FDDI as well, but we'll just say "Ethernet" below.

  Every system on an Ethernet network must have a unique Ethernet
  address for the network to operate properly. The physical Ethernet
  address of your system is the unique number assigned to the Ethernet
  hardware on your system. This unique number is assigned to the
  manufacturer of your Ethernet hardware by the IEEE (formerly by
  Xerox, one of the original developers of Ethernet). This is not to be
  confused with the IP address, which can be set arbitrarily.

  You may need to determine your system's Ethernet address if your
  network manager requires it before connecting your system to a
  network.  How to do so depends on whether IRIX is running and what
  operating system version is loaded.  Method 1 only provides the
  Ethernet address of the primary interface.  If you have multiple
  Ethernet interfaces (boards) in a system, use method 2, 3, 4 or 5 to
  determine the address(es) of any other interface(s).

  METHOD 1: eaddr

      If IRIX is not running, and the system is a Personal IRIS (4D20,
      25, 30, or 35), Indigo, Crimson, Onyx, Challenge, Indy, O2, 
      or Indigo2, you can obtain the Ethernet address by typing 'eaddr'
      (older machines) or 'printenv eaddr' (newer) at the PROM monitor .
      prompt.  On some machines (4D30 or later) you can say 'nvram eaddr'
      while IRIX is running to get the same result.

  METHOD 2: netstat

      Under IRIX 4.0.1 or later, you can use the netstat command. For
      example,

      % /usr/etc/netstat -ia
      Name  Mtu    Network   Address            Ipkts   Ierrs   Opkts  Oerrs  Coll
      ec0   1500   siligrph  luey7              7765678 21648  384477     0  30338
  			    192.48.200.251
  			    192.0.0.1
  			    08:00:69:06:17:c2
      lo0   32880  loopback localhost           41438       0   41438     0      0
  			    192.0.0.1

      As seen on the fourth address line, the address of the system
      luey7's primary Ethernet interface, "ec0", is 08:00:69:06:17:c2.

  METHOD 3: arp

      You can obtain the Ethernet address of a Silicon Graphics system
      by using another system on your network. 'ping' the system whose
      Ethernet address you want, then use 'arp'. For example,

      % /usr/etc/ping -c 1 luey6
      PING luey6.sgi.com (192.48.200.250): 56 data bytes
      64 bytes from 192.48.200.250: icmp_seq=0 ttl=255 time=0 ms
      ----luey6.sgi.com PING Statistics----
      3 packets transmitted, 3 packets received, 0% packet loss
      round-trip (ms)  min/avg/max = 0/0/0
      % /usr/etc/arp luey6
      luey6 (192.48.200.250) at 8:0:69:6:c:40
      %

  METHOD 4: NetVizualyzer/FDDIVizualyzer and the like

      SGI's NetVizualyzer/FDDIVizualyzer network monitoring software
      and at least one public domain equivalent ('netman', at
      ftp://ftp.cs.curtin.edu.au/pub/netman/) allow you to find the
      Ethernet address corresponding to any IP address. Read the
      manual.

  METHOD 5: System Manager

      The Network Setup part ('cnet') of the Indigo Magic System Manager 
      tool ('chost') shows the Ethernet address of each interface.

  4DDN: A Special Case

      DECnet uses a one-to-one relationship between the DECnet node ID
      and the Ethernet address. If the DECnet address is changed the
      Ethernet address is changed. DECnet Ethernet addresses always
      start with aa:, so you can identify systems running DECnet with
      'arp -a'.

      4DDN is Silicon Graphics' DECnet interconnection product. The
      Ethernet address of an IRIS running 4DDN will change when 4DDN is
      started.  Method 1 will return the original Ethernet address for
      the system.  Methods 2-5 will show the Ethernet address currently
      in use.

  sysinfo

      /etc/sysinfo is intended to return a unique identifier, which on
      some machines includes part or all of the Ethernet address. This
      is best regarded as an amusing coincidence, like HAL's name in
      "2001".  Don't rely on it.

  You can find an Ethernet address from a program most efficiently by
  using the SIOCGIFADDR ioctl on a raw socket (SOCK_RAW) using the
  RAWPROTO_SNOOP protocol (thanks to David Peter
  <davep@isltd.insignia.com>) but the program must run as root. If you
  can't run as root, call one of the above programs with system().