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omshell(1)              FreeBSD General Commands Manual             omshell(1)

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 being shepherded by Ted Lemon, and 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 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.  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 was written by Ted Lemon of Nominum, Inc.  Information about
       Nominum and support contracts for DHCP and BIND can be found at
       http://www.nominum.com. This preliminary documentation was written by
       Wendy Verschoor of Nominum, Inc., while she was testing omshell.

                                                                    omshell(1)

NAME | SYNOPSIS | DESCRIPTION | CONTRIBUTIONS | LOCAL AND REMOTE OBJECTS | OPENING A CONNECTION | CREATING LOCAL OBJECTS | ASSOCIATING LOCAL AND REMOTE OBJECTS | VIEWING A REMOTE OBJECT | MODIFYING A REMOTE OBJECT | NEW REMOTE OBJECTS | RESETTING ATTRIBUTES | REFRESHING OBJECTS | DELETING OBJECTS | HELP | SEE ALSO | AUTHOR

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