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server.pcy(4)
NAME
  server.pcy - BOOTP and DHCP server policy

DESCRIPTION
  server.pcy is a text database which governs the behavior of BOOTP and DHCP
  servers.  If joind is invoked to use text databases, it expects to read
  server.pcy on startup. If the variable JOINCONFIG is present in joind's
  environment, it is taken to be the directory where server.pcy is housed;
  otherwise /etc/join is searched.  Defaults exist for all parameters and
  switches, so it is not an error if the file does not exist.

  FORMAT


  Blank lines are ignored.  The character '#' introduces a comment which
  continue to the next newline. Each new policy option must begin and end on
  a separate line.  Policy options are introduced by a keyword, and may be
  boolean, or may take a value separated from the keyword by whitespace (but
  not a newline). If an option is present more than once, only the value
  attached to the last occurrence will be take effect - earlier value(s) will
  be forgotten.

  KEYWORDS AND VALUES


  provisional_ttl seconds
  For each subnet that the BOOTP and DHCP server administers two lists are
  maintained in memory: a "free" list containing IP addresses available for
  allocation, and a "provisional" list contain addresses which have been
  tentatively assigned, which are awaiting client approval in the form of a
  DHCPREQUEST packet.

  The value seconds determines how long an address will remain on the free
  list before the server determines that the client does not want the offered
  address.  The free list does not contain every address available to the
  server; instead it acts as a cache of addresses which the server can offer
  without reading the disk.

  If a new client makes a DHCPDISCOVER, and no IP address exists for the
  client in permanent store, the server will first go to the free list for an
  unused address.  If the free list is exhausted, the server will first
  reclaim any addresses on the provisional list which have expired.  It will
  then extend this list to be free_list_size(qv.) in length by reading from
  the disk.  This has  a benefit in that addresses are usually offered in
  numerically increasing order. Making the ttl too short will not give
  clients an opportunity to confirm offered addresses; making it too long
  will waste memory.
  Default: 60

  free_list_size integer See the explanation under provisional_ttl.  If this
  number is too low, server response time will suffer. If it is too large it
  has the undesirable effect of requiring the server to reclaim expired
  leases before they are actually needed for re-allocation to new clients.
  Although this is not an error, a desirable feature of server operation is
  that, whenever possible, a client requesting a new IP address should get
  back its old address, unless that address has been leases to a new client.
  Default: 8

  assign_name_by_hwaddr This and the next option are mutually exclusive.
  They govern how the server assigns names to hosts.  This option tells the
  server to make a name "move with" the MAC address. I.e. if the client moves
  to a new address, it keeps the same name.

  assign_name_by_ipaddr This tells the server that if a lookup to the name
  service ( gethostbyaddr(3) succeeds, the client should receive the name
  that was found at the IP address.

  accept_client_name This boolean option is not incompatible with previous
  options. It essentially tells the server that, if it has not be able to
  find a name for the client by application of the two previous policies,
  then it can accept the name the client suggests for itself providing that
  this would not be in contradiction with values currently in the name
  service. If a contradiction exists, or this policy is not enabled, then
  joind would consult its namepool or prefix.  (See namepool(4)).

  support_bootp This boolean tells joind to support BOOTP clients. When
  replying to BOOTP clients, the server does not use the DHCP extensions to
  the BOOTP protocol.  This is disabled by default.

  bootp_addr_from_pool This boolean is only valid if support_bootp option is
  enabled.  When on it permits the server to permanently assign an IP address
  from its free pool to a BOOTP client in the event that no permanent binding
  exists in dhcpcap.  Normally the BOOTP and DHCP server can only service
  BOOTP clients for which such a binding pre-exists.

  ping_timeout Before the server offers an IP address to a client it may
  first check that the address is not in use by sending an ICMP echo request.
  If an echo is received it means that the address is in use, and the server
  will select another. This parameter specifies the time (in milliseconds)
  that the server will wait for the echo. If this value is zero or negative
  the server will not perform this check. Disabling this check may be
  necessary in certain environments to decrease server response time to an
  acceptable level - this release of joind is not multi-threaded, so the
  server idles while awaiting the response.

RELATED INFORMATION
  namepool(4),
  DARPA Internet Request For Comments RFC1541, RFC1542.