Provided by: isc-dhcp-server_4.3.5-3ubuntu9_amd64 bug

NAME

       omshell - OMAPI Command Shell

SYNOPSIS

       omshell

DESCRIPTION

       The  OMAPI  Command  Shell, omshell, provides an interactive way to connect to, query, and
       possibly change, the ISC DHCP Server's state via OMAPI, the  Object  Management  API.   By
       using  OMAPI and omshell, you do not have to stop, make changes, and then restart the DHCP
       server, but can make the changes while the server is running.  Omshell provides a  way  of
       accessing OMAPI.

       OMAPI  is  simply  a  communications  mechanism that allows you to manipulate objects.  In
       order to actually use omshell, you must understand what objects are available and  how  to
       use  them.   Documentation  for  OMAPI  objects  can be found in the documentation for the
       server that provides them - for example, in the dhcpd(1) manual page and  the  dhclient(1)
       manual page.

CONTRIBUTIONS

       This software is free software.  At various times its development has been underwritten by
       various organizations, including the ISC and Vixie Enterprises.  The  development  of  3.0
       has been funded almost entirely by Nominum, Inc.

       At  this point development is hosted by the ISC, but the future of this project depends on
       you.  If you have features you want, please consider implementing them.

LOCAL AND REMOTE OBJECTS

       Throughout this document, there are references to local and remote objects.  Local objects
       are  ones created in omshell with the new command.  Remote objects are ones on the server:
       leases, hosts, and groups that the DHCP server knows about.  Local and remote objects  are
       associated  together  to  enable viewing and modification of object attributes.  Also, new
       remote objects can be created to match local objects.

OPENING A CONNECTION

       omshell is started from the command line.  Once omshell  is  started,  there  are  several
       commands that can be issued:

       server address
            where  address  is  the  IP address of the DHCP server to connect to.  If this is not
            specified, the default server is 127.0.0.1 (localhost).

       port number
            where number is the port that OMAPI listens on.  By default, this is 7911.

       key name secret
            This specifies the TSIG key to use to authenticate the OMAPI transactions.   name  is
            the  name of a key defined in dhcpd.conf with the omapi-key statement.  The secret is
            the secret key generated from dnssec-keygen or another key generation program.

       connect
            This starts the OMAPI connection to the server as specified by the server statement.

CREATING LOCAL OBJECTS

       Any object defined in OMAPI can be created, queried, and/or modified.   The  object  types
       available  to  OMAPI are defined in dhcpd(8) and dhclient(8).  When using omshell, objects
       are first defined locally, manipulated as desired, and then associated with an  object  on
       the server.  Only one object can be manipulated at a time.  To create a local object, use

       new object-type
            object-type is one of group, host, or lease.

       At  this  point, you now have an object that you can set properties on.  For example, if a
       new lease object was created with new lease, any of a lease's attributes  can  be  set  as
       follows:

       set attribute-name = value
            Attribute  names are defined in dhcpd(8) and dhclient(8).  Values should be quoted if
            they are strings.  So, to set a lease's IP address, you would do the following:
             set ip-address = 192.168.4.50

ASSOCIATING LOCAL AND REMOTE OBJECTS

       At this point, you can query the server for information about this lease, by

       open

       Now, the local lease object you created and set the IP address for is associated with  the
       corresponding  lease object on the DHCP server.  All of the lease attributes from the DHCP
       server are now also the attributes on the local object, and will be shown in omshell.

VIEWING A REMOTE OBJECT

       To query a lease of address 192.168.4.50, and find out its attributes, after connecting to
       the server, take the following steps:

       new lease

       This creates a new local lease object.

       set ip-address = 192.168.4.50

       This sets the local object's IP address to be 192.168.4.50

       open

       Now,  if  a  lease  with that IP address exists, you will see all the information the DHCP
       server has about that particular lease.  Any data that isn't readily printable  text  will
       show  up  in  colon-separated  hexadecimal  values.  In this example, output back from the
       server for the entire transaction might look like this:

       > new "lease"
       obj: lease
       > set ip-address = 192.168.4.50
       obj: lease
       ip-address = c0:a8:04:32
       > open
       obj: lease
       ip-address = c0:a8:04:32
       state = 00:00:00:02
       dhcp-client-identifier = 01:00:10:a4:b2:36:2c
       client-hostname = "wendelina"
       subnet = 00:00:00:06
       pool = 00:00:00:07
       hardware-address = 00:10:a4:b2:36:2c
       hardware-type = 00:00:00:01
       ends = dc:d9:0d:3b
       starts = 5c:9f:04:3b
       tstp = 00:00:00:00
       tsfp = 00:00:00:00
       cltt = 00:00:00:00

       As you can see here, the IP address is represented in hexadecimal, as are the starting and
       ending times of the lease.

MODIFYING A REMOTE OBJECT

       Attributes  of  remote  objects  are  updated by using the set command as before, and then
       issuing an update command.  The set command sets  the  attributes  on  the  current  local
       object, and the update command pushes those changes out to the server.

       Continuing  with  the  previous  example,  if a set client-hostname = "something-else" was
       issued, followed by an update command, the output would look about like this:

       > set client-hostname = "something-else"
       obj: lease
       ip-address = c0:a8:04:32
       state = 00:00:00:02
       dhcp-client-identifier = 01:00:10:a4:b2:36:2c
       client-hostname = "something-else"
       subnet = 00:00:00:06
       pool = 00:00:00:07
       hardware-address = 00:10:a4:b2:36:2c
       hardware-type = 00:00:00:01
       ends = dc:d9:0d:3b
       starts = 5c:9f:04:3b
       tstp = 00:00:00:00
       tsfp = 00:00:00:00
       cltt = 00:00:00:00
       > update
       obj: lease
       ip-address = c0:a8:04:32
       state = 00:00:00:02
       dhcp-client-identifier = 01:00:10:a4:b2:36:2c
       client-hostname = "something-else"
       subnet = 00:00:00:06
       pool = 00:00:00:07
       hardware-address = 00:10:a4:b2:36:2c
       hardware-type = 00:00:00:01
       ends = dc:d9:0d:3b
       starts = 5c:9f:04:3b
       tstp = 00:00:00:00
       tsfp = 00:00:00:00
       cltt = 00:00:00:00

NEW REMOTE OBJECTS

       New remote objects are created much in the same  way  that  existing  server  objects  are
       modified.   Create  a local object using new, set the attributes as you'd wish them to be,
       and then create the remote object with the same properties by using

       create

       Now a new object exists on the DHCP server which matches the properties that you gave your
       local object.  Objects created via OMAPI are saved into the dhcpd.leases file.

       For  example,  if  a  new  host with the IP address of 192.168.4.40 needs to be created it
       would be done as follows:

       > new host
       obj: host
       > set name = "some-host"
       obj: host
       name = "some-host"
       > set hardware-address = 00:80:c7:84:b1:94
       obj: host
       name = "some-host"
       hardware-address = 00:80:c7:84:b1:94
       > set hardware-type = 1
       obj: host
       name = "some-host"
       hardware-address = 00:80:c7:84:b1:94
       hardware-type = 1
       > set ip-address = 192.168.4.40
       obj: host
       name = "some-host"
       hardware-address = 00:80:c7:84:b1:94
       hardware-type = 1
       ip-address = c0:a8:04:28
       > create
       obj: host
       name = "some-host"
       hardware-address = 00:80:c7:84:b1:94
       hardware-type = 00:00:00:01
       ip-address = c0:a8:04:28
       >

       Your dhcpd.leases file would then have an entry like this in it:

       host some-host {
         dynamic;
         hardware ethernet 00:80:c7:84:b1:94;
         fixed-address 192.168.4.40;
       }

       The dynamic; line is to denote that this host entry did not come from dhcpd.conf, but  was
       created dynamically via OMAPI.

RESETTING ATTRIBUTES

       If you want to remove an attribute from an object, you can do this with the unset command.
       Once you have unset an attribute, you must use the update command  to  update  the  remote
       object.   So,  if the host "some-host" from the previous example will not have a static IP
       address anymore, the commands in omshell would look like this:

       obj: host
       name = "some-host"
       hardware-address = 00:80:c7:84:b1:94
       hardware-type = 00:00:00:01
       ip-address = c0:a8:04:28
       > unset ip-address
       obj: host
       name = "some-host"
       hardware-address = 00:80:c7:84:b1:94
       hardware-type = 00:00:00:01
       ip-address = <null>
       >

REFRESHING OBJECTS

       A local object may be refreshed with  the  current  remote  object  properties  using  the
       refresh  command.  This is useful for object that change periodically, like leases, to see
       if they have been updated.  This isn't particularly useful for hosts.

DELETING OBJECTS

       Any remote object that can be created can also be destroyed.  This is done by  creating  a
       new  local object, setting attributes, associating the local and remote object using open,
       and then using the remove command.  If the host "some-host" from  before  was  created  in
       error, this could be corrected as follows:

       obj: host
       name = "some-host"
       hardware-address = 00:80:c7:84:b1:94
       hardware-type = 00:00:00:01
       ip-address = c0:a8:04:28
       > remove
       obj: <null>
       >

HELP

       The help command will print out all of the commands available in omshell, with some syntax
       pointers.

SEE ALSO

       dhcpctl(3), omapi(3), dhcpd(8), dhclient(8), dhcpd.conf(5), dhclient.conf(5).

AUTHOR

       omshell is maintained by ISC.  To  learn  more  about  Internet  Systems  Consortium,  see
       https://www.isc.org

                                                                                       omshell(1)