| NDBOOTD(8) | System Manager's Manual | NDBOOTD(8) | 
ndbootd —
| ndbootd | [ -sboot2]
      [-iinterface]
      [-wwindowsize]
      [-d] boot1 | 
ndbootd is a server which supports the Sun Network Disk
  (ND) Protocol. This protocol was designed by Sun before they designed NFS. ND
  simply makes the raw blocks of a disk available to network clients. Contrast
  this with the true namespace and file abstractions that NFS provides.
The only reason you're likely to encounter ND nowadays is if you have an old Sun 2 machine, like the 2/120 or 2/50. The Sun 2 PROMs can only use ND to boot over the network. (Later, the Sun 3 PROMs would use RARP and TFTP to boot over the network.)
ndbootd is a very simple ND server that
    only supports client reads for booting. It exports a disk that the clients
    consider to be /dev/ndp0 (ND public unit zero). The
    disk is available only to clients that are listed in
    /etc/ethers and have valid hostnames. (Sun 2 PROMs
    don't do RARP, but they do learn their IP address from the first ND response
    they receive from the server.)
boot1 is a file containing the mandatory first-stage network boot program, typically /usr/mdec/bootyy. The layout of the exported disk is:
With the -s boot2
    option, ndbootd will also make a second-stage
    network boot program available to clients, typically
    /usr/mdec/netboot. When boot2
    is a filename, that file is the single second-stage network boot program to
    be served to all clients.
When boot2 is a directory name, typically
    /tftpboot, ndbootd finds a
    client's second-stage network boot program by turning its IP address into a
    filename in that directory, in the same manner later Sun 3 PROMs do when
    TFTPing (i.e., if a client has IP address 192.168.1.10,
    ndbootd expects to find
    /tftpboot/C0A8010A.SUN2 ).
When used in this last manner with an ND-aware first-stage boot
    program, ndbootd serves the same purpose in the Sun
    2 netboot process as tftpd(8)
    serves in the Sun 3 netboot process.
Any second-stage network boot program always begins at block 16 of the exported disk, regardless of the length of the first-stage network boot program.
All first- and second-stage network boot programs must have all executable headers stripped off; they must be raw binary programs.
The remaining options are:
-i
    interfacendbootd listens for clients on the first
      non-loopback IP interface that is up and running.-w
    windowsize-d| May 9, 2001 | NetBSD 10.1 |