FortiGate Administration Guide - FirewallShop.com

System DHCP
FortiGate DHCP servers and relays
System DHCP
This section describes how to use DHCP to provide convenient automatic network
configuration for your clients.
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 their assigned IP
address. Optionally, they can also obtain default gateway and DNS server
settings. A FortiGate interface or VLAN subinterface can provide the following
DHCP services:
• Regular DHCP servers for regular Ethernet connections
• 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).
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.
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 131.
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 131.
DHCP services can also be configured through the Command Line Interface
(CLI). See the FortiGate CLI Reference for more information.
FortiGate Version 3.0 MR5 Administration Guide
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