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server.pcy(4)							 server.pcy(4)

       server.pcy - BOOTP and DHCP server policy

       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	direc‐
       tory  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.

       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 iden‐
       tifiers.	  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 idetfi‐
       fiers).	 This  is disabled by default.	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 containing  addresses	 that  have  been  tentatively
       assigned,  which	 are awaiting client approval in the form of a DHCPRE‐
       QUEST 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  con‐
	      tain 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 confirm 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
	      reallocation to new clients.  Although this is not an  error,  a
	      desirable	 feature  of server operation is that, whenever possi‐
	      ble, a client requesting a new IP address should	get  back  its
	      old  address,  unless  that  address  has	 been  leased to a new

	      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 name‐
	      pool(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  mil‐
	      liseconds) that the server waits for the echo.  If this value is
	      zero or negative, the server does not perform this check.	  Dis‐
	      abling  this  check  may be necessary in certain environments to
	      decrease server response	time  to  an  acceptable  level;  this
	      release of joind is not multithreaded, so the server idles while
	      awaiting the response.

       Files: namepool(4)

       Specifications: RFC 1541, RFC 1542 delim off


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