Subtitle: Configure the DHCP

Version and revision: V1.0 / R 0.0.

For Nethserver 6.6 and above.

Accessible to: Novice / Beginner

Date of presentation: Released on 2016-03-19

The DHCP ( Dynamic Host Configuration Protocol) server centralizes the management of the local network configuration for any device connected to it. When a computer (or a device such as a printer, smartphone, etc.) connects to the local network, it can ask the network configuration parameters by means of the DHCP protocol. The DHCP server replies, providing the IP, DNS, and other relevant network parameters.

In most cases, the devices are already configured to use DHCP protocol on start up.

The Preboot eXecution Environment (PXE) specification allows a network device to retrieve the operating system from a centralized network location while starting up, through the DHCP and TFTP protocols.

DHCP configuration

The DHCP server can be enabled on all green and blue interfaces (see Network). NethServer will assign a free IP address within the configured DHCP range in DHCP > DHCP server page.

The DHCP range must be defined within the network of the associated interface. For instance, if the green interface has IP/netmask 192.168.1.1/255.255.255.0 the range must be 192.168.1.2 - 192.168.1.254.

Host IP reservation

The DHCP server leases an IP address to a device for a limited period of time. If a device requires to always have the same IP address, it can be granted an IP reservation associated to its MAC address.

The page DHCP > IP reservation lists the currently assigned IP addresses:

a line with IP reservation button identifies an host with a temporary lease (gray color); a line with Edit button identifies an host with a reserved IP (black color). A small two arrows icon near the host name says the DHCP lease is expired: this is a normal condition for hosts with static IP configuration, as they never contact the DHCP server.