Configure an Interface as a DHCP Server

Select an interface to be a DHCP Server.
Select
Network
DHCP
DHCP Server
and
Add
an
Interface
name or select one.
For
Mode
, select
enabled
or
auto
mode. Auto mode enables the server and disables it if another DHCP server is detected on the network. The
disabled
setting disables the server.
(
Optional
) Select
Ping IP when allocating new IP
if you want the server to ping the IP address before it assigns that address to its client.
If the ping receives a response, that means a different device already has that address, so it is not available. The server assigns the next address from the pool instead. This behavior is similar to Optimistic Duplicate Address Detection (DAD)forIPv6,RFC 4429.
After you set options and return to the DHCP server tab, the
Probe IP
column for the interface indicates if
Ping IP when allocating new IP
was selected.
Configure the predefined DHCP Options that the server sends to its clients.
In the Options section, select a
Lease
type:
Unlimited
causes the server to dynamically choose IP addresses from the
IP Pools
and assign them permanently to clients.
Timeout
determines how long the lease will last. Enter the number of
Days
and
Hours
, and optionally the number of
Minutes
.
Inheritance Source
—Leave
None
or select a source DHCP client interface or PPPoE client interface to propagate various server settings into the DHCP server. If you specify an
Inheritance Source
, select one or more options below that you want
inherited
from this source.
Specifying an inheritance source allows the firewall to quickly add DHCP options from the upstream server received by the DHCP client. It also keeps the client options updated if the source changes an option. For example, if the source replaces its NTP server (which had been identified as the
Primary NTP
server), the client will automatically inherit the new address as its
Primary NTP
server.
When inheriting DHCP option(s) that contain multiple IP addresses, the firewall uses only the first IP address contained in the option to conserve cache memory. If you require multiple IP addresses for a single option, configure the DHCP options directly on that firewall rather than configure inheritance.
Check inheritance source status
—If you selected an
Inheritance Source
, clicking this link opens the
Dynamic IP Interface Status
window, which displays the options that were inherited from the DHCP client.
Gateway
—IP address of the network gateway (an interface on the firewall) that is used to reach any device not on the same LAN as this DHCP server.
Subnet Mask
—Network mask used with the addresses in the
IP Pools
.
For the following fields, click the down arrow and select
None
, or
inherited
, or enter a remote server’s IP address that your DHCP server will send to clients for accessing that service. If you select
inherited
, the DHCP server inherits the values from the source DHCP client specified as the
Inheritance Source
.
Primary DNS
,
Secondary DNS
—IP address of the preferred and alternate Domain Name System (DNS) servers.
Primary WINS
,
Secondary WINS
—IP address of the preferred and alternate Windows Internet Naming Service (WINS) servers.
Primary NIS
,
Secondary NIS
—IP address of the preferred and alternate Network Information Service (NIS) servers.
Primary NTP
,
Secondary NTP
—IP address of the available Network Time Protocol servers.
POP3 Server
—IP address of Post Office Protocol (POP3) server.
SMTP Server
—IP address of a Simple Mail Transfer Protocol (SMTP) server.
DNS Suffix
—Suffix for the client to use locally when an unqualified hostname is entered that it cannot resolve.
(
Optional
) Configure a vendor-specific or custom DHCP option that the DHCP server sends to its clients.
In the Custom DHCP Options section,
Add
a descriptive
Name
to identify the DHCP option.
Enter the
Option Code
you want to configure the server to offer (range is 1-254). (See RFC 2132 for option codes.)
If the
Option Code
is
43
, the
Vendor Class Identifier
field appears. Enter a VCI, which is a string or hexadecimal value (with 0x prefix) used as a match against a value that comes from the client Request containing option 60. The server looks up the incoming VCI in its table, finds it, and returns Option 43 and the corresponding option value.
Inherit from DHCP server inheritance source
—Select it only if you specified an
Inheritance Source
for the DHCP Server predefined options and you want the vendor-specific and custom options also to be
inherited
from this source.
Check inheritance source status
—If you selected an
Inheritance Source
, clicking this link opens
Dynamic IP Interface Status
, which displays the options that were inherited from the DHCP client.
If you did not select
Inherit from DHCP server inheritance source
, select an
Option Type
:
IP Address
,
ASCII
, or
Hexadecimal
. Hexadecimal values must start with the 0x prefix.
Enter the
Option Value
you want the DHCP server to offer for that
Option Code
. You can enter multiple values on separate lines.
Click
OK
.
(
Optional
) Add another vendor-specific or custom DHCP option.
Repeat the prior step to enter another custom DHCP Option.
You can enter multiple option values for an
Option Code
with the same
Option Name
, but all values for an
Option Code
must be the same type (
IP Address
,
ASCII
, or
Hexadecimal
). If one type is inherited or entered and a different type is entered for the same
Option Code
and the same
Option Name
, the second type will overwrite the first type.
When entering multiple values for an option, enter the values in the order of preference, or else move the Custom DHCP Options to achieve the preferred order in the list. Select an option and click
Move Up
or
Move Down
.
You can enter an
Option Code
more than once by using a different
Option Name
. In this case, the
Option Type
for the Option Code can differ among the multiple option names.
Click
OK
.
Identify the stateful pool of IP addresses from which the DHCP server chooses an address and assigns it to a DHCP client.
If you are not the network administrator for your network, ask the network administrator for a valid pool of IP addresses from the network plan that can be designated to be assigned by your DHCP server.
In the
IP Pools
field,
Add
the range of IP addresses from which this server assigns an address to a client. Enter an IP subnet and subnet mask (for example, 192.168.1.0/24) or a range of IP addresses (for example, 192.168.1.10-192.168.1.20).
An IP Pool or a
Reserved Address
is mandatory for dynamic IP address assignment.
An IP Pool is optional for static IP address assignment as long as the static IP addresses that you assign fall into the subnet that the firewall interface services.
(
Optional
) Repeat this step to specify another IP address pool.
(
Optional
) Specify an IP address from the IP pools that will not be assigned dynamically. If you also specify a
MAC Address
, the
Reserved Address
is assigned to that device when the device requests an IP address through DHCP.
See the DHCP Addressing section for an explanation of allocation of a
Reserved Address
.
In the
Reserved Address
field, click
Add
.
Enter an IP address from the
IP Pools
(format x.x.x.x) that you do not want to be assigned dynamically by the DHCP server.
(
Optional
) Specify the
MAC Address
(format xx:xx:xx:xx:xx:xx) of the device to which you want to permanently assign the IP address you just specified.
(
Optional
) Repeat the prior two steps to reserve another address.
Commit your changes.
Click
OK
and
Commit
.