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dhcpcemu(8)							  dhcpcemu(8)



NAME

  dhcpcemu - Emulate a DHCP client

SYNOPSIS

  /usr/sbin/dhcpcemu [-b] [-q] [-m  | -n  | -v]	[-dn] [-a server_address] [-c
  client_address] [-e hardware_address]	[-h hostname] [-i client_identifier]
  [-r requested_address] [-p bootp | discover |	renew |	rebind | request |
  select | decline] [-s	size] [-t timeout] [-f file] interface

OPTIONS

  -b  Sets the broadcast bit.

  -q  Runs quietly: display neither the	contents of the	incoming nor the out-
      going packets.

  -m |-n |-v
      Sets the magic cookie in the outgoing packet to be the CMU (-m) or the
      RFC1048 (-v ) value (the default).  The -n option	means to use no
      cookie at	all.

  -a server_address
      The server identifier field in the options of the	outgoing packet	is
      set to the IP address.  To properly emulate a client in the selecting
      DHCP state, this field is	required regardless of the value given with
      the -p option.

  -c client_address
      Sets the ciaddr field in the packet to the value client_address or to
      the IP address of	the interface chosen if	client_address equals
      0.0.0.0.

  -e hardware_address
      Pretend to be at the given hardware (MAC)	address. The chaddr field is
      set to hardware_address.	Unless the broadcast bit is also set, this
      usually means that no replies will be received, as the server or relay
      agents will normally try a link-level unicast to the phony address.

  -h hostname
      Sets the hostname	option in the outgoing packet to the given value.

  -i client_identifier
      Sets the client identifier option	in the outgoing	packet to the given
      string. The string is treated literally, not as a	hex representation of
      an arbitrary octet string.

  -r requested_address
      Sets the IP address value	in the outgoing	packet.	This option is
      required if the outgoing packet is to validly represent a	client in the
      DHCP states selecting or rebooting or in a DHCP DECLINE message.

  -p  The string following determines the kind of BOOTP	or DHCP	packet sent,
      and whether the packet is	broadcast or unicast.  The default is to emu-
      late a BOOTP client.

  -s size
      Sends a packet of	size octets (by	default	548 octets).

  -t timeout
      Exits after timeout seconds if no	responses are received.

  -f file
      Sets the file field in the outgoing packet to the	given string.

DESCRIPTION

  The dhcpcemu command emulates	a DHCP/BOOTP client.  Options are provided to
  set the most important fields	in the BOOTP request packet.  A	packet is
  constructed, is sent through the interface specified,	and a reply awaited.
  The emulator exits after the first reply is received or for a	length of
  time specified by the	-t option. Depending on	the options specified and/or
  the DHCP server configuration, no reply may in fact be forthcoming. If no
  timeout is specified,	the emulator may be killed with	any suitable asyn-
  chronous signal.  The	SIGINT signal (usually generated from the keyboard
  with Ctrl/c) is available if dhcpcemu	is running in the foreground.

  It is	important to note that with the	options	available, it is quite possi-
  ble to create	an illegal packet. This	is one of the primary functions	of
  dhcpcemu; to test the	behavior of servers when confronted with packets that
  do not conform to the	standards.

RESTRICTIONS

  A cluster member should never	be a DHCP client. It should always use static
  addressing.

  If a cluster is to support a DHCP server, there can be only one DHCP server
  for all the cluster members using a common database with failover.

SEE ALSO

  RFC2031, RFC2032