RPi-DHCP-Server

This project aims to prepare a RPi 3 as a DHCP server for an intranet (no Internet).

Enable SSH (Optional)

sudo raspi-config

From the menu, select 5 Interfacing Options --> P2 SSH.

Install TightVNC¹ & XRDP² servers (Optional)

Note¹: TightVNC is a cross-platform free and open-source remote desktop software application.

Note²: XRDP is an open-source implementation of Microsoft RDP (Remote Desktop Protocol) server.

sudo apt-get install tightvncserver -y
sudo apt-get install xrdp -y

Install gedit³ (Optional)

Note³: gedit is a general-purpose text editor with a clean and simple GUI.

sudo apt-get install gedit -y

Install ISC DHCP server⁴

sudo apt-get install isc-dhcp-server -y

Note⁴: ISC DHCP server is a DHCP server program that operates as a daemon to provide Dynamic Host Configuration Protocol service to a network.

Assign static IP 192.168.1.1 to the RPi

Edit dhcpcd.conf with gedit (you can replace gedit with nano).

sudo gedit /etc/dhcpcd.conf

Add the following lines to the end of the document, save, and then exit.

interface eth0
static ip_address=192.168.1.1/24
static routers=192.168.1.1

Setup the DHCP Server

Edit dhcpd.conf with gedit (you can replace gedit with nano).

sudo gedit /etc/dhcp/dhcpd.conf

Add the following lines to the end of the document, save, and then exit.

subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.16 192.168.1.239;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255;
option routers 192.168.1.1;
}

The DHCP server will allocate IP addresses ranging from 192.168.1.16 to 192.168.1.239 to all clients connected to its eth0 which are running as DHCP clients.

Edit isc-dhcp-server with gedit (you can replace gedit with nano).

sudo gedit /etc/default/isc-dhcp-server

Add eth0 to INTERFACESv4, such that

INTERFACESv4="eth0"
INTERFACESv6=""

Load the new settings and reboot.

sudo dhcpd -cf /etc/dhcp/dhcpd.conf
sudo reboot

Remarks [1]

The DHCP server may not load properly when eth0 is not yet ready while booting. To solve that, one can enable Restart on Failure and add a delay of 5-10 seconds. To do that, edit isc-dhcp-server.service as follows

sudo cp /run/systemd/generator.late/isc-dhcp-server.service /etc/systemd/system
sudo gedit /etc/systemd/system/isc-dhcp-server.service

At the [Service] section, modify the add the following

Restart=on-failure,
RestartSec=5

At the end of the document, add the following

[Install]
WantedBy=multi-user.target

Apply the new settings.

sudo systemctl daemon-reload
sudo systemctl disable isc-dhcp-server
sudo systemctl enable isc-dhcp-server

References

[1] https://raspberrypi.stackexchange.com/questions/70517/isc-dhcp-server-needs-to-be-restarted-after-reboot?rq=1