server.pcy(4)						     Kernel Interfaces Manual						     server.pcy(4)

NAME

       server.pcy - BOOTP and DHCP server policy

DESCRIPTION

       The  server.pcy	file  is  a text database that governs the behavior of BOOTP and DHCP servers.	If the joind daemon is invoked to use text
       databases, it reads the server.pcy file on startup.  If the JOINCONFIG variable is present in  the  joind  environment,	it  specifies  the
       directory  for  the server.pcy file; otherwise, joind searches the /etc/join directory.	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 number sign character (#) introduces a comment, which continues 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	is
       used; earlier value(s) are ignored.

   Keywords and Values
       This Boolean tells the server that if a DHCP client needs a boot file, send the name of that file in the BOOTP file field and not as a DHCP
       option (option 67).  BOOTP clients always receive a boot file name in the file field.  This is disabled by default.  This Boolean tells the
       server  to  ignore  the	value  of the broadcast bit and always broadcast a reply, even when the client can receive a pseudo unicast reply.
       This was needed by some Cabletron smart bridges.  This is disabled by default.  This Boolean is for clients that do  not  use  DHCP  client
       identifiers.   The parameter tells the server to use the client's hardware address as its identifier, but to ignore the hadware type field.
       In the JOIN database, the identifier is stored with a type field of zero (which is also the type for those clients that	are  using  client
       idetfifiers).   This  is disabled by default.  For each subnet that the BOOTP and DHCP server administers, two lists are maintained in mem-
       ory: a "free" list containing IP addresses available for allocation and a "provisional" list containing addresses  that	have  been  tenta-
       tively assigned, which are awaiting client approval in the form of a DHCPREQUEST packet.

	      The  value  of 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 first goes to the free
	      list for an unused address.  If the free list is exhausted, the server first reclaims any addresses on the  provisional  list  which
	      have  expired.   It  then  extends  this	list  to be free_list_size 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 con-
	      firm offered addresses; making it too long will waste memory.

	      Default:	60  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  realloca-
	      tion  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 leased to a new client.

	      Default: 8 This option and the "assign_name_by_ipaddr" option are mutually exclusive.  They govern how the server assigns  names	to
	      hosts.  This option tells the server to bind a name to the MAC address. That way, if the client moves to a new address, it keeps the
	      same name.  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.  This Boolean option is compatible with previous options.	It instructs the server that if it
	      is not able to find a name for the client by application of the two previous policies, it can accept the name  the  client  suggests
	      for  itself  providing  that  this is not in contradiction with values currently in the name service.  If a contradiction exists, or
	      this policy is not enabled, joind consults its namepool or prefix.  (See namepool(4)).  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 enabled by
	      default.	This Boolean is only valid if the support_bootp option is enabled.  When on support_bootp permits  the	server	to  perma-
	      nently  assign  an  IP address from its free pool to a BOOTP client in the event that no permanent binding exists in bootptab.  Nor-
	      mally the BOOTP and DHCP server can only service BOOTP clients for which such a binding pre-exists.  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 selects another.  This parameter specifies the  time  (in  milliseconds)  that  the
	      server  waits for the echo.  If this value is zero or negative, the server does 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

       Files: namepool(4)

       Specifications: RFC 1541, RFC 1542 delim off

																     server.pcy(4)