#top Konfiguracja¶

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O ile nie zdefiniowano inaczej wszystkie poniższe opcje dotyczą pliku konfiguracyjnego dhcpd.conf dostępnego standardowo w lokalizacji /etc/dhcp/dhcpd.conf (lub /etc/dhcpd/dhcpd.conf).

#top include¶

Dokumentacja DHCPd: REFERENCE: DECLARATIONS
Składnia include "filename";
Opis: The include statement

The include statement is used to read in a named file, and process the contents of that file as though it were entered in place of the include statement.

Examples:
Zmiany jakie należy wprowadzić w pliku /etc/dhcpd/dhcpd.conf:

# dhcpd eth0 and eth1 moved
#include "/etc/dhcpd/eth0-dhcpd.conf";
#include "/etc/dhcpd/eth1-dhcpd.conf";
include "/etc/dhcpd/virbr1-dhcpd.conf";
include "/etc/dhcpd/virbr2-dhcpd.conf";
include "/etc/dhcpd/virbr3-dhcpd.conf";
include "/etc/dhcpd/virbr4-dhcpd.conf";
include "/etc/dhcpd/virbr5-dhcpd.conf";

Zmiany jakie należy wprowadzić w pliku /etc/dhcpd/virbr1-dhcpd.conf:

#
# virbr1-dhcpd.conf
#

subnet ... netmask ... {
	# hosts fixed address
	include "/etc/dhcpd/virbr1-hosts.conf";
}

#top Listen¶

Dokumentacja DHCPd: COMMAND LINE
Dokumentacja DHCPd: PORTS
Składnia (argumenty wiersza poleceń): dhcpd [...] [ if0 [ ...ifN ]]
Opis:

The names of the network interfaces on which dhcpd should listen for broadcasts may be specified on the command line. This should be done on systems where dhcpd is unable to identify non-broadcast interfaces, but should not be required on other systems. If no interface names are specified on the command line dhcpd will identify all network interfaces which are up, eliminating non-broadcast interfaces if possible, and listen for DHCP broadcasts on each interface.

Examples:
Zmiany jakie należy wprowadzić w pliku /etc/sysconfig/dhcpd:

# Define INTERFACES to limit which network interfaces dhcpd listens on.
# The default null value causes dhcpd to listen on all interfaces.
# INTERFACES=""
INTERFACES="virbr1 virbr2 virbr3 virbr4 virbr5"

#top ddns-updates¶

Dokumentacja DHCPd: REFERENCE: PARAMETERS
Składnia ddns-updates flag;
Opis: The ddns-updates statement

The ddns-updates parameter controls whether or not the server will attempt to do a DNS update when a lease is confirmed. Set this to off if the server should not attempt to do updates within a certain scope. The ddns-updates parameter is on by default. To disable DNS updates in all scopes, it is preferable to use the ddns-update-style statement, setting the style to none.

Examples:
Zmiany jakie należy wprowadzić w pliku /etc/dhcpd/dhcpd.conf:

# Use this to enble / disable dynamic dns updates globally.
ddns-updates on;

#top ddns-update-style¶

Dokumentacja DHCPd: REFERENCE: PARAMETERS
Składnia ddns-update-style style;
Opis: The ddns-update-style parameter

The style parameter must be one of ad-hoc, interim or none. The ddns-update-style statement is only meaningful in the outer scope - it is evaluated once after reading the dhcpd.conf file, rather than each time a client is assigned an IP address, so there is no way to use different DNS update styles for different clients. The default is none.

Examples:
Zmiany jakie należy wprowadzić w pliku /etc/dhcpd/dhcpd.conf:

# Use this to enble / disable dynamic dns updates globally.
#ddns-update-style none;
#ddns-update-style on;
ddns-update-style ad-hoc;

#top authoritative¶

Dokumentacja DHCPd: REFERENCE: PARAMETERS
Składnia authoritative;, not authoritative;,
Opis: The authoritative statement

The DHCP server will normally assume that the configuration information about a given network segment is not known to be correct and is not authoritative. This is so that if a naive user installs a DHCP server not fully understanding how to configure it, it does not send spurious DHCPNAK messages to clients that have obtained addresses from a legitimate DHCP server on the network.
Network administrators setting up authoritative DHCP servers for their networks should always write authoritative; at the top of their configuration file to indicate that the DHCP server should send DHCPNAK messages to misconfigured clients. If this is not done, clients will be unable to get a correct IP address after changing subnets until their old lease has expired, which could take quite a long time.
Usually, writing authoritative; at the top level of the file should be sufficient. However, if a DHCP server is to be set up so that it is aware of some networks for which it is authoritative and some networks for which it is not, it may be more appropriate to declare authority on a per-network-segment basis.
Note that the most specific scope for which the concept of authority makes any sense is the physical network segment - either a shared-network statement or a subnet statement that is not contained within a shared-network statement. It is not meaningful to specify that the server is authoritative for some subnets within a shared network, but not authoritative for others, nor is it meaningful to specify that the server is authoritative for some host declarations and not others.
The style parameter must be one of ad-hoc, interim or none. The ddns-update-style statement is only meaningful in the outer scope - it is evaluated once after reading the dhcpd.conf file, rather than each time a client is assigned an IP address, so there is no way to use different DNS update styles for different clients. The default is none.

Examples:
Zmiany jakie należy wprowadzić w pliku /etc/dhcpd/dhcpd.conf:

# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;
authoritative;

#top subnet statement¶

Dokumentacja DHCPd: REFERENCE: DECLARATIONS
Składnia

subnet subnet-number netmask netmask {
[ parameters ]
[ declarations ]
}

Opis: The subnet statement

The subnet statement is used to provide dhcpd with enough information to tell whether or not an IP address is on that subnet. It may also be used to provide subnet-specific parameters and to specify what addresses may be dynamically allocated to clients booting on that subnet. Such addresses are specified using the range declaration.
The subnet-number should be an IP address or domain name which resolves to the subnet number of the subnet being described. The netmask should be an IP address or domain name which resolves to the subnet mask of the subnet being described. The subnet number, together with the netmask, are sufficient to determine whether any given IP address is on the specified subnet.
Although a netmask must be given with every subnet declaration, it is recommended that if there is any variance in subnet masks at a site, a subnet-mask option statement be used in each subnet declaration to set the desired subnet mask, since any subnet-mask option statement will override the subnet mask declared in the subnet statement.

Examples:
Zmiany jakie należy wprowadzić w pliku /etc/dhcpd/dhcpd.conf:

#
# virbr1-dhcpd.conf
#

subnet 10.41.0.0 netmask 255.255.0.0 {
[...]
}

#top option values¶

#top option routers¶

Dokumentacja DHCPd: SETTING OPTION VALUES USING EXPRESSIONS
Składnia option routers ip-address [, ip-address... ];
Opis:

The routers option specifies a list of IP addresses for routers on the client’s subnet. Routers should be listed in order of preference.