• Run the following command to start the installation:

sudo apt update
sudo apt install isc-dhcp-server

• You may check the DHCP version:

dhcpd --version

• Configure the network interfaces that the DHCP server will use by editing the config file:

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

• For example, if your DHCP interface is tap_vpn, update the line as follows:

INTERFACESv4="tap_vpn"

• Configure the DHCP setting by editing the config file:

sudo nano /etc/dhcp/dhcpd.conf

• This part set the domain name and DNS servers:

option domain-name "example.com";
option domain-name-servers 8.8.8.8, 8.8.4.4;

• This part set the subnet and IP address range:

subnet 192.168.30.0 netmask 255.255.255.0 {
range 192.168.30.100 192.168.30.200;
option routers 192.168.30.1;
}

• Set the lease time:

default-lease-time 600;
max-lease-time 7200;

• Assign IP address to the device before started the DHCP service (this is mandatory):

sudo ip addr add 192.168.30.1/24 dev tap_vpn

• Start the service:

sudo systemctl start isc-dhcp-server

• Enable the service:

sudo systemctl enable isc-dhcp-server

• Show the service status:

sudo systemctl status isc-dhcp-server

• Check the DHCP server logs for any error messages:

sudo tail -f /var/log/syslog | grep dhcpd

• Verify that the DHCP server is listening on the correct network interface:

sudo netstat -uap | grep dhcpd