dhcp_network man page on SmartOS

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       dhcp_network - DHCP network tables

       The  Dynamic Host Configuration Protocol (DHCP) network tables are used
       to map the client identifiers of DHCP clients to IP addresses  and  the
       associated  configuration  parameters of that address. One DHCP network
       table exists for each network served by the DHCP server, and each table
       is named using the network's IP address. There is no table or file with
       the name dhcp_network.

       The DHCP network tables can exist as  ASCII  text  files,  binary  text
       files, or NIS+ tables, depending on the data store used. Since the for‐
       mat of the file could change, the preferred method of managing the DHCP
       network tables is through the use of dhcpmgr(1M) or the pntadm(1M) com‐

       The dhcp_network file  is  used	as  a  policy  mechanism  for  whether
       in.dhcpd(1M) leases addresses on a given network. If the DHCP server is
       not serving leases or information to a  network,	 there	should	be  no
       dhcp_network  file for that network. To set the DHCP server in informa‐
       tional mode, where it responds to INFORM messages but  does  not	 lease
       addresses  on  that network, create an empty dhcp_network file for that
       network. For normal operations,	where  the  DHCP  server  both	leases
       addresses  and  responds	 to INFORM packets, create a dhcp_network file
       using  dhcpmgr(1M)  or  pntadm(1M)  and	populate  it   with   leasable

       The  format  of the records in a DHCP network table depends on the data
       store used to maintain the table. However, an entry in a	 DHCP  network
       table must contain the following fields:

		     The client identifier field, Client_ID, is an ASCII hexa‐
		     decimal representation of the unique octet	 string	 value
		     of	 the  DHCP  Client  Identifier	Option (code 61) which
		     identifies a DHCP client. In  the	absence	 of  the  DHCP
		     Client  Identifier	 Option, the DHCP client is identified
		     using the form given below for BOOTP clients. The	number
		     of	 characters in this field must be an even number, with
		     a maximum length of 64 characters. Valid characters are 0
		     - 9 and A-F.  Entries with values of 00 are freely avail‐
		     able for dynamic allocation to requesting clients.	 BOOTP
		     clients  are  identified by the concatenation of the net‐
		     work's hardware type (as  defined	by  RFC	 1340,	titled
		     "Assigned	Numbers")  and	the client's hardware address.
		     For example, the following BOOTP client  has  a  hardware
		     type  of  '01'  (10mb ethernet) and a hardware address of
		     8:0:20:11:12:b7,  so  its	client	identifier  would  be:

		     The  Flags	 field	is  a decimal value, the bit fields of
		     which can have a combination of the following values:

		     1 (PERMANENT)
				       Evaluation of the Lease field is turned
				       off  (lease  is permanent). If this bit
				       is not set,  Evaluation	of  the	 Lease
				       field  is  enabled  and	the  Lease  is

		     2 (MANUAL)
				       This entry has a manual client ID bind‐
				       ing   (cannot   be  reclaimed  by  DHCP
				       server). Client will not	 be  allocated
				       another address.

		     4 (UNUSABLE)
				       When  set, this value means that either
				       through ICMP echo  or  client  DECLINE,
				       this address has been found to be unus‐
				       able. Can also be used by  the  network
				       administrator   to  prevent  a  certain
				       client from booting, if	used  in  con‐
				       junction with the MANUAL flag.

		     8 (BOOTP)
				       This  entry  is reserved for allocation
				       to BOOTP clients only.

		     The Client_IP field holds the IP address for this	entry.
		     This value must be unique in the database.

		     This  field holds the IP address of the DHCP server which
		     owns this client IP address, and thus is responsible  for
		     initial  allocation  to  a requesting client. On a multi-
		     homed DHCP server, this IP	 address  must	be  the	 first
		     address returned by gethostbyname(3NSL).

		     This numeric field holds the entry's absolute lease expi‐
		     ration time, and is in seconds since January 1, 1970.  It
		     can  be  decimal, or hexadecimal (if 0x prefixes number).
		     The special value -1 is used to denote a permanent lease.

		     This ASCII text field contains  the  dhcptab  macro  name
		     used  to look up this entry's configuration parameters in
		     the dhcptab(4) database.

		     This ASCII text field contains an optional comment.

       This section describes how the DHCP/BOOTP server calculates a  client's
       configuration  lease  using information contained in the dhcptab(4) and
       DHCP network tables. The server consults the LeaseTim and LeaseNeg sym‐
       bols  in	 the  dhcptab, and the Flags and Lease fields of the chosen IP
       address record in the DHCP network table.

       The server first examines the Flags field for the identified DHCP  net‐
       work table record. If the PERMANENT flag is on, then the client's lease
       is considered permanent.

       If the PERMANENT flag is not on, the  server  checks  if	 the  client's
       lease as represented by the Lease field in the network table record has
       expired. If the lease is not expired, the server checks if  the	client
       has requested a new lease. If the LeaseNeg symbol has not been included
       in the client's dhcptab parameters, then the client's  requested	 lease
       extension  is ignored, and the lease is set to be the time remaining as
       shown by the Lease field. If the LeaseNeg  symbol  has  been  included,
       then  the  server  will	extend	the  client's  lease  to  the value it
       requested if this requested lease is less than or equal to the  current
       time plus the value of the client's LeaseTim dhcptab parameter.

       If the client's requested lease is greater than policy allows (value of
       LeaseTim), then the client is given a lease equal to the	 current  time
       plus  the  value	 of LeaseTim. If LeaseTim is not set, then the default
       LeaseTim value is one hour.

       For more information about the dhcptab symbols, see dhcptab(4).

       See attributes(5) for a description of the following attribute:

       │Interface Stability │ Evolving	      │

       dhcpconfig(1M),	dhcpmgr(1M),  dhtadm(1M),  in.dhcpd(1M),   pntadm(1M),
       dhcptab(4), dhcp(5), dhcp_modules(5), attributes(5)

       Solaris DHCP Service Developer's Guide

       System Administration Guide: IP Services

       Reynolds,  J.  and  J.  Postel,	Assigned  Numbers,  STD	 2,  RFC 1340,
       USC/Information Sciences Institute, July 1992.

				  Mar 5, 2004		       DHCP_NETWORK(4)

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