Technical Tip: How to configure a FortiGate interface to use DHCP

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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.

The steps to edit an interface and enable DHCP are shown only for the GUI.

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 (non-HA).

Solution

Configuration (GUI).

1. Log in to the FortiGate.

2. From the navigation pane, go to Network -> Interfaces.

3. Edit the interface connecting to the ISP, by selecting the 'edit' icon.

4. Change the addressing mode to DHCP  .

5. 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.

6. If the ISP also provides the DNS settings, enable the field 'Override internal DNS'.

7. Select OK.

8. The 'Status' should change to connected and show the IP information obtained (IP address, default gateway, DNS).
   
   

GUI page: FortiGate Interface to use DHCP.