How to Use dnsmasq on Linux

The dnsmasq utility is a compact server application for Linux. It handles DNS, DHCP, PXE, TFTP, and router advertisement tasks. Unlike heavyweight DNS solutions, dnsmasq keeps things simple. It works best for home networks and small office setups.

When a query arrives, dnsmasq checks its local cache first. If no match is found, it passes the request to an upstream resolver, such as Google’s public DNS. The tool also reads your system’s /etc/hosts file for local name resolution and responds to DHCP-configured machines.

Getting dnsmasq Ready on Your Machine

Confirm whether dnsmasq already exists on your system:

$ dnsmasq --version

If you see a version number, everything is set. Otherwise, grab it with your package manager.

On Ubuntu or Debian-based distros:

$ sudo apt install dnsmasq

On Fedora:

$ sudo dnf install dnsmasq

Basic dnsmasq Command Format

The general pattern looks like this:

$ dnsmasq [options]

Pass flags to control DNS cache capacity, DHCP address pools, config file paths, and more.

Key dnsmasq Flags and Their Purpose

If your dnsmasq instance will listen on a non-standard port, make sure that port is open in your firewall. The guide to opening ports on Linux walks through the steps for ufw and firewalld.

Practical dnsmasq Usage Scenarios

Launching with default behavior

Run dnsmasq without any flags to fire it up using standard settings:

$ dnsmasq

Your configuration must be valid before doing this. Review config files with a terminal editor like nano to check for syntax problems.

Activating query logging

Track every DNS request by appending the -q flag. To redirect logs into a separate file, pair it with -8:

$ dnsmasq -q --log-facility=/home/user/dnsmasq.log

This approach is helpful for troubleshooting network problems. Inspect log output with tools like grep or tail.

Running dnsmasq as a DHCP provider

Assign addresses automatically across your LAN by specifying an IP pool and lease duration:

$ dnsmasq -F 192.168.10.80,192.168.10.160,6h

Addresses between 192.168.10.80 and 192.168.10.160 get allocated here. Each lease lasts six hours.

Restricting to one network adapter

Force dnsmasq to accept traffic on a single interface only:

$ dnsmasq -i enp0s0

Combining several flags together

Mix multiple options in one command. The example below listens on a specific adapter, allocates DHCP addresses, blocks host file loading, and enables query logging:

$ dnsmasq --interface=enp0s0 --dhcp-range=192.168.10.80,192.168.10.160,6h --no-hosts --log-queries

Storing All dnsmasq Options Inside a Config File

Typing long commands repeatedly gets tedious. Place every setting inside a dedicated file instead. Open a new file with any editor:

$ sudo nano /etc/custom.conf

Add your preferred settings there. Before launching, validate the syntax:

$ dnsmasq -C /etc/custom.conf --test

If no errors appear, boot the server with:

$ dnsmasq -C /etc/custom.conf

To confirm dnsmasq is listening after startup, list running processes with ps aux | grep dnsmasq or check with ss -lntp | grep :53.

Wrapping Up

dnsmasq remains one of the most practical solutions for managing DNS and DHCP on small networks. Its low resource footprint makes it a good fit where a full-featured server would be overkill. With caching, forwarding, filtering, and PXE boot support packed into a single binary, dnsmasq covers a wide range of networking needs without added complexity.