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For any subnet on which addresses will be assigned dynamically, there must be at least one
range
statement. The range statement gives the lowest and highest IP addresses in a range. All IP addresses in
the range should be in the subnet in which the
range
statement is declared. The
dynamic-bootp
flag may
be specified if addresses in the specified range may be dynamically assigned to BOOTP clients as well as
DHCP clients. When specifying a single address,
high-address
can be omitted.
Host
host
hostname
{
[
parameters
]
[
declarations
]
}
There must be at least one
host
statement for every BOOTP client that is to be served.
Host
statements
may also be specified for DHCP clients, although this is not required unless booting is only enabled for
known hosts. If it is desirable to be able to boot a DHCP or BOOTP client on more than one subnet with
fixed addresses, more than one address may be specified in the
fixed-address
parameter, or more than one
host statement may be specified. If client-specific boot parameters must change based on the network to
which the client is attached, then multiple
host
statements should be used. If a client is to be booted using
a fixed address if it’s possible, but should be allocated a dynamic address otherwise, then a
host
statement must be specified without a
fixed-address
clause.
hostname
should be a name identifying the
host. If a
hostname
option is not specified for the host,
hostname
is used. Host declarations are matched to
actual DHCP or BOOTP clients by matching the
dhcp-client-identifier
option specified in the
host
declaration to the one supplied by the client, or, if the
host
declaration or the client does not provide a
dhcp-client-identifier
option, by matching the
hardware
parameter in the
host
declaration to the network
hardware address supplied by the client. BOOTP clients do not normally provide a
dhcp-client-identifie
r,
so the hardware address must be used for all clients that may boot using the BOOTP protocol.
Group
group { [ parameters ] [ declarations ] }
The group statement is used simply to apply one or more parameters to a group of declarations.
It can be used to group hosts, shared networks, subnets, or even other groups.
8.4.3 ALLOW and DENY
The
allow
and
deny
statements can be used to control the behaviour of the DHCP server in response to
various sorts of requests.
unknown-clients
allow unknown-clients;
deny unknown-clients;
The
unknown-clients
flag is used to tell the DHCP server whether or not to dynamically assign addresses
to unknown clients. Dynamic address assignment to unknown clients is
allo
wed by default.
bootp
allow bootp;
deny bootp;
The
bootp
flag is used to tell the DHCP server whether or not to respond to BOOTP queries. BOOTP
queries are
allo
wed by default.
booting
allow booting;
deny booting;
The
booting
flag is used to inform the DHCP server whether or not to respond to queries from a
particular client. This keyword only has meaning when it appears in a
host
declaration. By default,
booting is
allo
wed, but if it is disabled for a particular client, then that client will not be able to get and
address from the DHCP server.
8.4.4 Parameters
default-lease-time
