75
dynamic-bootp-lease-length
dynamic-bootp-lease-length
lengt
h;
The
dynamic-bootp-lease-length
statement is used to set the length of leases dynamically assigned to
BOOTP clients. At some sites, it may be possible to assume that a lease is no longer in use if its holder
has not used BOOTP or DHCP to get its address within a certain time period. The period is specified in
length
as a number of seconds. If a client reboots using BOOTP during the timeout period, the lease
duration is reset to
lengt
h, so a BOOTP client that boots frequently enough will never lose its lease.
Needless to say, this parameter should be adjusted with extreme caution.
use-host-decl-names
use-host-decl-names flag;
If the
use-host-decl-names
parameter is true in a given scope, then for every host declaration within that
scope, the name provided for the host declaration will be supplied to the client as its hostname. For
example:
group {
use-host-decl-names on;
host joe {
hardware ethernet 08:00:2b:4c:29:32;
fixed-address joe.fugue.com;
}
}
is equivalent to
host joe {
hardware ethernet 08:00:2b:4c:29:32;
fixed-address joe.fugue.com;
option host-name "joe";
}
An
option host-name
statement within a host declaration will override the use of the name in the host
declaration.
server-identifier
server-identifier
hostnam
e;
The server-identifier statement can be used to define the value that is sent in the DHCP Server Identifier
option for a given scope. The value specified
must
be an IP address for the DHCP server, and must be
reachable by all clients served by a particular scope. The use of the server-identifier statement is not
recommended - the only reason to use it is to force a value other than the default value to be sent on
occasions where the default value would be incorrect. The default value is the first IP address associated
with the physical network interface on which the request arrived. The usual case where the
server-identifier
statement needs to be sent is when a physical interface has more than one IP address, and
the one being sent by default is not appropriate for some or all clients served by that interface.
8.4.5 Option statements
The DHCP server can supply values for all options given in RFC2132, including those which the DHCP
client cannot use for configuration (this is to allow option support on, for example, Microsoft clients,
which should support a much wider range of configuration options). The available options are as
follows.
option subnet-mask
ip-addres
s;
The subnet mask option specifies the client’s subnet mask as per RFC 950. If no subnet mask option
is provided anywhere in scope, DHCP will use the subnet mask from the subnet declaration for the
network on which an address is being assigned. However, any subnet-mask option declaration that
is in scope for the address being assigned will override the subnet mask specified in the subnet
declaration.
option time-offset
int3
2;
The time-offset option specifies the offset of the client’s subnet in seconds from Coordinated
Universal Time (UTC).
