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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
      outgoing 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
      emulate 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
  asynchronous 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
  possible 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

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