Description
This article describes how a user can configure a FortiGate interface to use DHCP (Dynamic Host Configuration Protocol). DHCP is a way to assign automatically an IP address to a network device.
In a FortiGate where an interface IP is assigned by an ISP, DHCP may have to be used. In these scenarios an ISP will often also provide a Default Route and the DNS settings.
Scope
Applies only to:
- FortiGate or VDOM in NAT mode.
- FortiGate in Standalone mode or in HA mode, when in HA mode (Technical Tip: FortiGate HA and dynamic interface support (DHCP, PPPoE)) it is suggested to enable DHCP after the cluster has been configured.
Solution
Configuration (GUI):
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Log in to the FortiGate.
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From the navigation pane, go to Network -> Interfaces.
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Edit the interface connecting to the ISP by selecting the 'edit' icon.
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Change the addressing mode to DHCP.
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Enable 'Retrieve default gateway from server'. This will place a default route in the routing table with a distance as shown in the distance field. In this example, the distance is 5.
- If the ISP also provides the DNS settings, enable the field 'Override internal DNS'.
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Select OK.
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The 'Status' should change to connected and show the IP information obtained (IP address, default gateway, DNS).
GUI page: FortiGate Interface to use DHCP.
Example configuration in the CLI:
config system interface
edit "port1"
set mode dhcp
set defaultgw enable
set dns-server-override enable
next
end
