10. DHCP

The Dynamic Host Configuration Protocol (DHCP) automatically assigns IP addresses and related configuration information, such as the subnet mask and default gateway. The general DHCP settings are under Network -> DHCP and DNS -> General Settings. 

Interface DHCP server

An interface with the “static address” protocol can be set up to serve DHCP requests. To do this, navigate to Network -> Interfaces and create or edit an interface. Ensure the protocol under General Settings is set to “Static address,” then under the interface tab DHCP Server, use the Set up DHCP Server button to configure the server for the interface. Under the tab General Setup, ensure the Ignore interface option is unchecked, and set the desired Start of the leased address range, Limit on the maximum number of leased addresses, and expiry Lease time.

Static lease

To ensure the DHCP always leases the same IP address, a static lease can be set up to assign a fixed IP address.

If it is required that the DHCP always assigns the same IP address to a connected device, a static lease has to be set up. This can be done in two ways: either the required static IP address is specified, or we only need the address to stay the same, but the specific address is not unspecified.

Specified

To set up a static lease with a specified IP address, navigate to Network -> DHCP and DNS -> Static Leases. Any active DHCP leases can be seen under the section Active DHCP leases, and new leases can be set via the Add button.

Then, the parameters of the static lease can be set:

Hostname: The symbolic name which is assigned to the requesting host.

MAC address: MAC address of the device to which the fixed IP address will be assigned.

IPv4 address: The fixed IP address which will be assigned.

Lease time: A non-standard host-specific lease time can be set, e.g., 12h, 3d or infinite.

Optionally, the DHCP Unique Identifier (DUID) and the IPv6 suffix (hex) can be set.

Unspecified

If the assigned IP address is irrelevant, an active DHCP lease can be set as static in Status -> Overview under the section Active DHCP Leases via the Set Static button. 

Deleting or editing a static lease

Any active static lease can be changed or removed under Network -> DHCP and DNS -> Static Leases.