omshell(1)						      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 pro-
       vides 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 com-
       mand.  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  (local-
	    host).

       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 was written by Ted Lemon of Nominum, Inc.  Information about Nominum can be found at http://www.nominum.com.  This preliminary doc-
       umentation was written by Wendy Verschoor of Nominum, Inc., while she was testing omshell.

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