dhcpd.leases - DHCP client lease database
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.
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;
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
corrupted,
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.
/var/db/dhcpd.leases
dhcp-options(5), dhcpd.conf(5), dhcpd(8)
RFC 2132, RFC 2131.
dhcpd(8) was written by Ted Lemon <[email protected]> under a
contract with
Vixie Labs.
The current implementation was reworked by
Henning Brauer <[email protected]>.
OpenBSD 3.6 January 1, 1997
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