Knowledge base → Installing and configuring a DHCP server in Linux Debian 12

A DHCP server is required to allocate IP addresses to devices connected to the server directly or through a router. This service is usually used on local networks. In this guide, we will configure a DHCP server on which there are 2 external ports, 1 for connecting to the Internet and the other for the local network.

#1. Install packages

apt install isc-dhcp-server

1.1 Pre-configuration

In file:

nano /etc/default/isc-dhcp-server

Let's uncomment the timing and bring the file to the form where in the INTERFACESv4 field we indicate the port for the local network, in our case enp1s0.

DHCPDv4_CONF=/etc/dhcp/dhcpd.conf
DHCPDv4_PID=/var/run/dhcpd.pid
INTERFACESv4="enp1s0"

1.2 Configuring the enp1s0 interface itself if it is not configured

/etc/network/interfaces

auto enp1s0
     iface enp1s0 inet static
     address 100.100.100.1
     netmask 255.255.255.0

1.2.1 Restart the service

service networking restart

1.3 Basic settings for dhcp service

nano /etc/dhcp/dhcpd.conf

option domain-name "localhost.localdomain";
option domain-name-servers 100.100.100.1;
default-lease-time 32400;
max-lease-time 604800;
log-facility local7;
authoritative;

subnet 100.100.100.0 netmask 255.255.255.0 {
   range 100.100.100.2 100.100.100.250;
   option broadcast-address 100.100.100.255;
   option routers 100.100.100.1;
}

1.3.1 Setting up a static IP by MAC address

nano /etc/dhcp/dhcpd.conf

host mini-pc {
     hardware ethernet 06:e0:4c:6a:04:14;
     fixed-address 100.100.100.101;
}

1.4 Let's start the service and add it to startup

systemctl start isc-dhcp-server
systemctl enable isc-dhcp-server

1.5 Add rules to iptables

iptables -A INPUT -p tcp --dport 67 -j ACCEPT
iptables-save > /etc/iptables/rules.v4

1.6 Logging

If it is necessary to include a log file, install the service:

apt install rsyslog

Let's add the configuration:

nano /etc/rsyslog.conf

local7.* /var/log/dhcpd.log

Let's restart the service

systemctl restart rsyslog
systemctl restart isc-dhcp-server.service

A log file will be created and accessed at /var/log/dhcpd.log

The setup is complete, the server is configured and distributes IP addresses to devices connected via a port dedicated to the local network.