DHCP and DNS Configuration: Basics

This guide explains how to set up DHCP and DNS servers on a Debian-based system. We'll use isc-dhcp-server for dynamic IP address assignment and bind9 for DNS resolution.

1. Setting Up the DHCP Server

1.1 Install the DHCP server

sudo apt update
sudo apt install isc-dhcp-server

1.2 Configure the DHCP Server

Edit the main configuration file:

sudo nano /etc/dhcp/dhcpd.conf

Add the following configuration:

subnet 192.168.1.0 netmask 255.255.255.0 {
    range 192.168.1.140 192.168.1.150;
    option routers 192.168.1.254;
    option domain-name-servers 192.168.1.100;
}

• range: the IP addresses the server can assign.
• routers: the default gateway.
• domain-name-servers: DNS server to use.

1.3 Set the Listening Interface

Edit:

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

Set the network interface (e.g., eth0, wlan0):

INTERFACESv4="wlan0"

1.4 Restart the DHCP Service

sudo systemctl restart isc-dhcp-server

2. Setting Up the DNS Server (BIND9)

2.1 Install BIND9

sudo apt install bind9 bind9utils bind9-doc -y

2.2 Define a DNS Zone

Edit:

sudo nano /etc/bind/named.conf.local

Add:

zone "0x3adomain.com" IN {
    type master;
    file "/etc/bind/db.0x3adomain.com";
};

2.3 Create the Zone File

Create the file:

sudo nano /etc/bind/db.0x3adomain.com

Example content:

$TTL    604800
@       IN      SOA     0x3adomain.com. root.0x3adomain.com. (
                          1         ; Serial
                          604800    ; Refresh
                          86400     ; Retry
                          2419200   ; Expire
                          604800    ; Negative Cache TTL
)

@       IN      NS      ns.0x3adomain.com.
@       IN      A       192.168.1.100
ns      IN      A       192.168.1.100

2.4 Restart DNS Services

sudo systemctl restart bind9
sudo systemctl restart systemd-resolved

2.5 Test DNS Resolution

Use dig to test:

dig 0x3adomain.com

If there are errors, review the zone file and check the status of bind9.

Conclusion

You’ve now configured a basic DHCP server for IP assignment and a DNS server for name resolution on Debian. This setup provides a solid base for managing a local network. You can explore advanced options like static leases, reverse zones, or DNSSEC as next steps.