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
Sets the broadcast bit. Runs quietly: display neither the
contents of the incoming nor the outgoing packets. 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 0.0.0.0.
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. 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. 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
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.
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.
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