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  man pages->OpenBSD man pages -> dhcpd.leases (5)              



NAME    [Toc]    [Back]

     dhcpd.leases - DHCP client lease database

DESCRIPTION    [Toc]    [Back]

     The Internet Software Consortium DHCP Server keeps a persistent database
     of  leases  that  it has assigned.  This database is a freeform ASCII file
     containing a series of lease  declarations.   Every  time  a
lease is acquired,
  renewed  or  released, its new value is recorded at
the end of the
     lease file.  So if more than one declaration appears  for  a
given lease,
     the last one in the file is the current one.

FORMAT    [Toc]    [Back]

     Lease  descriptions are stored in a format that is parsed by
the same recursive
 descent parser used to read the dhcpd.conf(5) and
     dhclient.conf(5) files.   Currently,  the  only  declaration
that is used in
     the dhcpd.leases file is the lease declaration.

          lease ip-address { statements... }

     Each  lease  declaration includes the single IP address that
has been
     leased to the client.  The statements within the braces  define the duration
 of the lease and to whom it is assigned.

     The  start  and  end  time of a lease are recorded using the
``starts'' and
     ``ends'' statements:

           starts date;
           ends date;

     Dates are specified as follows:

          weekday year/month/day hour:minute:second

     The weekday is present to make it easy for a human  to  tell
when a lease
     expires  - it's specified as a number from zero to six, with
zero being
     Sunday.  The day of week is ignored on input.  The  year  is
specified with
     the  century,  so  it should generally be four digits except
for really long
     leases.  The month is specified as a number starting with  1
for January.
     The  day of the month is likewise specified starting with 1.
The hour is
     a number from 0 to 23, the minute a number from 0 to 59, and
the second
     also a number from 0 to 59.

     Lease  times  are  specified  in  Coordinated Universal Time
(UTC), not in the
     local time zone.

     The MAC address of the network interface that  was  used  to
acquire the
     lease is recorded with the hardware statement:

           hardware hardware-type mac-address;

     The  MAC  address  is  specified  as a series of hexadecimal
octets, separated
     by colons.

     If the client uses a client identifier to  acquire  its  address, the client
     identifier is recorded using the uid statement:

           uid client-identifier;

     The client identifier is recorded as a series of hexadecimal
octets, regardless
 of whether the client specifies an ASCII string  or
uses the newer
 hardware type/MAC address format.

     If the client sends a hostname using the Client Hostname option, as specified
 in some versions of the  DHCP-DNS  Interaction  draft,
that hostname
     is recorded using the client-hostname statement.

           client-hostname "hostname";

     If  the client sends its hostname using the Hostname option,
it is recorded
 using the hostname statement.

           hostname "hostname";

     The DHCP server may determine that a lease has been  misused
in some way,
     either  because a client that has been assigned a lease NAKs
it, or because
 the server's own attempt to see if an  address  is  in
use prior to
     reusing  it  reveals  that the address is in fact already in
use.  In that
     case, the abandoned statement will be used to indicate  that
the lease
     should not be reassigned.


     Abandoned leases are reclaimed automatically.  When a client
asks for a
     new address, and the server finds that there are no new  addresses, it
     checks  to  see if there are any abandoned leases, and allocates the least
     recently  abandoned  lease.   The  standard  mechanisms  for
checking for lease
     address  conflicts  are  still followed, so if the abandoned
lease's IP address
 is still in use, it will be reabandoned.

     If a client requests an abandoned address,  the  server  assumes that the
     reason the address was abandoned was that the lease file was
     and that the client is the machine that responded  when  the
lease was
     probed,  causing  it to be abandoned.  In that case, the address is immediately
 assigned to the client.

FILES    [Toc]    [Back]


SEE ALSO    [Toc]    [Back]

     dhcp-options(5), dhcpd.conf(5), dhcpd(8)

     RFC 2132, RFC 2131.

AUTHORS    [Toc]    [Back]

     dhcpd(8) was written by Ted Lemon <mellon@vix.com>  under  a
contract with
     Vixie Labs.

     The current implementation was reworked by
     Henning Brauer <henning@openbsd.org>.

OpenBSD      3.6                          January     1,     1997
[ Back ]
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