


dhcpd.leases(5)                                   dhcpd.leases(5)


NAME
       dhcpd.leases - DHCP client lease database

DESCRIPTION
       The  Internet Software Consortium DHCP Server keeps a per-
       sistent database of leases that  it  has  assigned.   This
       database  is  a  free-form ASCII file containing one valid
       declaration per  lease.   If  more  than  one  declaration
       appears  for  a  given  lease, the last one in the file is
       used.  The file is written as a log, so  this  is  not  an
       unusual occurrence.

       When dhcpd is first installed, there is no lease database.
       However, dhcpd requires that a lease database  be  present
       before it will start.  To make the initial lease database,
       just create an empty file called /var/db/dhcpd.leases.

       In order to prevent the lease database from growing  with-
       out  bound,  the  file  is  rewritten  from  time to time.
       First, a temporary lease database is created and all known
       leases are dumped to it.   Then, the old lease database is
       renamed /var/db/dhcpd.leases~.   Finally, the newly  writ-
       ten lease database is moved into place.

       There is a window of vulnerability where if the dhcpd pro-
       cess is killed or the system crashes after the  old  lease
       database  has been renamed but before the new one has been
       moved into place, there will be  no  /var/db/dhcpd.leases.
       In this case, dhcpd will refuse to start, and will require
       manual intervention.   DO NOT simply create  a  new  lease
       file when this happens - if you do, you will lose all your
       old bindings, and  chaos  will  ensue.    Instead,  rename
       /var/db/dhcpd.leases~  to  /var/db/dhcpd.leases, restoring
       the old, valid lease file, and then  start  dhcpd.    This
       guarantees that a valid lease file will be restored.

FORMAT
       The format of the lease declarations is not currently doc-
       umented.

FILES
       /var/db/dhcpd.leases

SEE ALSO
       dhcpd(8),   dhcp-options(5),    dhcpd.conf(5),    RFC2132,
       RFC2131.

AUTHOR
       dhcpd(8) was written by Ted Lemon <mellon@vix.com> under a
       contract with Vixie Labs.   Funding for this  project  was
       provided  by  the Internet Software Corporation.  Informa-
       tion about the Internet Software Consortium can  be  found
       at http://www.isc.org/isc.




                                                                1


