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Local Network Host Discovery via mDNS ( .local )

This guide explains how to configure macOS and Linux machines to advertise and resolve .local hostnames on your local network using Multicast DNS (mDNS) .

Use case: IP addresses change often on home networks. With mDNS, you can access machines via names like mymachine.local instead of tracking dynamic IPs.

Overview

Platform mDNS Support Required Setup
macOS Built-in (Bonjour) None
Linux Requires avahi Install + setup

macOS Setup (Zero Config)

macOS comes with Bonjour pre-installed. It automatically advertises your hostname on the .local domain.

View macOS Hostname 

scutil --get LocalHostName

Test from another device 

ping <mac-hostname>.local

Example: 

ping Jeremy-MacBook.local

Linux Setup (Ubuntu, Debian, Arch, etc.)

Linux systems require avahi-daemon and proper NSS configuration.

1. Install Required Packages 

sudo apt install avahi-daemon avahi-utils libnss-mdns

2. Enable and Start Avahi 

sudo systemctl enable --now avahi-daemon

3. Configure NSS ( /etc/nsswitch.conf )

Ensure this line includes mdns4_minimal : 

hosts: files mdns4_minimal [NOTFOUND=return] dns

4. Optional: Set a Friendly Hostname 

sudo hostnamectl set-hostname mymachine

This will advertise your machine as mymachine.local .

5. Test From Another Host 

ping mymachine.local

Or resolve the name: 

avahi-resolve-host-name mymachine.local

Firewall Requirements

Ensure your firewall allows:

Optional: List .local Devices on the Network 

avahi-browse -at

Or just scan for hostnames: 

avahi-browse -a | grep '^+.*IPv4' | awk '{print \$4}' | sort -u

Notes