dhcpcemu - Emulate a DHCP client
/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
-b Sets the broadcast bit.
-q Runs quietly: display neither the contents of the incoming nor the out-
-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.
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.
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
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.
Sets the hostname option in the outgoing packet to the given value.
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.
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.
Sends a packet of size octets (by default 548 octets).
Exits after timeout seconds if no responses are received.
Sets the file field in the outgoing packet to the given string.
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.
A cluster member should never be a DHCP client. It should always use static
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.