Fortinet FortiGate Series Administration Guide

System DHCP FortiGate DHCP servers and relays
FortiGate Version 4.0 MR1 Administration Guide
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System DHCP
This section describes how to use DHCP to provide convenient automatic network
configuration for your clients.
DHCP is not available in Transparent mode. DHCP requests are passed through the
FortiGate unit when it is in Transparent mode.
If you enable virtual domains (VDOMs) on the FortiGate unit, DHCP is configured
separately for each virtual domain. For details, see “Using virtual domains” on page 159.
This section describes:
• FortiGate DHCP servers and relays
• Configuring DHCP services
• Viewing address leases
FortiGate DHCP servers and relays
The DHCP protocol enables hosts to automatically obtain an IP address from a DHCP
server. Optionally, they can also obtain default gateway and DNS server settings. A
FortiGate interface or VLAN subinterface can provide the following DHCP services:
• Basic DHCP servers for non-IPSec IP networks
• IPSec DHCP servers for IPSec (VPN) connections
• DHCP relay for regular Ethernet or IPSec (VPN) connections
An interface cannot provide both a server and a relay for connections of the same type
(regular or IPSec).
You can configure one or more DHCP servers on any FortiGate interface. A DHCP server
dynamically assigns IP addresses to hosts on the network connected to the interface. The
host computers must be configured to obtain their IP addresses using DHCP.
If an interface is connected to multiple networks via routers, you can add a DHCP server
for each network. The IP range of each DHCP server must match the network address
range. The routers must be configured for DHCP relay.
To configure a DHCP server, see “Configuring a DHCP server” on page 229.
You can configure a FortiGate interface as a DHCP relay. The interface forwards DHCP
requests from DHCP clients to an external DHCP server and returns the responses to the
DHCP clients. The DHCP server must have appropriate routing so that its response
packets to the DHCP clients arrive at the FortiGate unit.
To configure a DHCP relay see “Configuring an interface as a DHCP relay agent” on
page 229.
DHCP services can also be configured through the Command Line Interface (CLI). See
the FortiGate CLI Reference for more information.
Note: You can configure a Regular DHCP server on an interface only if the interface has a
static IP address. You can configure an IPSec DHCP server on an interface that has either
a static or a dynamic IP address.

Fortinet FortiGate Series Specifications

General

Brand	Fortinet
Model	FortiGate Series
Category	Firewall
Language	English