Networking on macOS

macOS provides a sophisticated networking stack that blends traditional BSD networking tools with Apple’s modern network configuration frameworks. If you’re coming from Linux, you’ll find familiar concepts but different tools: there’s no ip command, no NetworkManager, and no systemd-networkd. Instead, macOS uses a combination of BSD utilities and Apple-specific tools like networksetup, scutil, and the configd daemon.

The macOS Network Architecture

At its core, macOS networking is built on:

┌─────────────────────────────────────────────────────────────┐
│                    Applications                              │
├─────────────────────────────────────────────────────────────┤
│                    Network Framework                         │
│              (URLSession, Network.framework)                 │
├─────────────────────────────────────────────────────────────┤
│  SystemConfiguration    │    Bonjour/mDNS    │    VPN       │
│     Framework           │   (mDNSResponder)  │   Framework  │
├─────────────────────────────────────────────────────────────┤
│                    configd daemon                            │
│              (System Configuration Agent)                    │
├─────────────────────────────────────────────────────────────┤
│                    BSD Network Stack                         │
│              (Sockets, TCP/IP, Routing)                     │
├─────────────────────────────────────────────────────────────┤
│                    XNU Kernel                                │
│        (Network interfaces, drivers, packet filtering)      │
└─────────────────────────────────────────────────────────────┘

Key Components

configd: The system configuration daemon that manages network state, detects changes, and notifies applications.

mDNSResponder: Handles Bonjour/mDNS, multicast DNS, and DNS service discovery. Also serves as the local DNS resolver.

SystemConfiguration Framework: Provides APIs for network configuration and state monitoring.

Command-Line Tools Overview

macOS provides several categories of networking tools:

Configuration Tools

Diagnostic Tools

DNS and Discovery

Wi-Fi Tools

Quick Network Status Check

Get a quick overview of your network configuration:

# Show all active interfaces with IPs
$ ifconfig | grep -E "^[a-z]|inet "
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
	inet 127.0.0.1 netmask 0xff000000
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	inet 192.168.1.100 netmask 0xffffff00 broadcast 192.168.1.255

# Show current default gateway
$ route get default | grep gateway
    gateway: 192.168.1.1

# Show DNS servers
$ scutil --dns | grep nameserver | head -5
  nameserver[0] : 192.168.1.1
  nameserver[1] : 8.8.8.8

# Show active network service
$ networksetup -listallnetworkservices | head -3
An asterisk (*) denotes that a network service is disabled.
Wi-Fi
Ethernet

Network Locations

macOS supports “Locations”—saved network configurations you can switch between:

# List locations
$ networksetup -listlocations
Automatic
Home
Office

# Get current location
$ networksetup -getcurrentlocation
Automatic

# Switch location
$ networksetup -switchtolocation "Office"

Locations are useful for laptops that move between different network environments with different proxy settings, DNS servers, or IP configurations.

What You’ll Learn in This Part

Network Configuration from CLI covers the essential tools for configuring network interfaces, IP addresses, DNS, and routing using networksetup, ipconfig, ifconfig, and scutil.

Understanding Network Services explains how macOS organizes network interfaces into services, how to manage network locations, and configure advanced features like VLANs.

Bonjour and mDNS introduces Apple’s zero-configuration networking technology, including how to browse and advertise services using the dns-sd command.

VPN Configuration shows how to configure and manage VPN connections from the command line, including IKEv2, L2TP/IPSec, and third-party VPN solutions.

Sharing Services via Command Line explains how to enable and configure macOS sharing services like SSH, Screen Sharing, and File Sharing from Terminal.

Network Diagnostics and Troubleshooting provides a comprehensive guide to troubleshooting network issues using ping, traceroute, mtr, nettop, tcpdump, and other diagnostic tools.

Wi-Fi Management from Terminal covers the hidden airport utility and other tools for scanning networks, connecting, and diagnosing Wi-Fi issues.

Quick Troubleshooting Guide

Common network issues and quick fixes:

Can’t Connect to Network

# Check if interface is up
$ ifconfig en0 | grep status
	status: active

# Renew DHCP lease
$ sudo ipconfig set en0 DHCP

# Restart network service
$ sudo ifconfig en0 down && sudo ifconfig en0 up

DNS Not Resolving

# Flush DNS cache
$ sudo dscacheutil -flushcache
$ sudo killall -HUP mDNSResponder

# Check DNS servers
$ scutil --dns | grep nameserver

# Test with specific DNS server
$ dig @8.8.8.8 example.com

Slow Network

# Test network quality (macOS 12+)
$ networkQuality -s

# Check for packet loss
$ ping -c 100 gateway_ip | grep "packet loss"

# Monitor real-time network activity
$ nettop -m tcp

Check What’s Using the Network

# See network connections by process
$ lsof -i -P | grep ESTABLISHED

# Real-time network usage by process
$ nettop -P

# See what's listening
$ lsof -i -P | grep LISTEN

The following chapters dive deep into each of these areas, providing the knowledge you need to configure, secure, and troubleshoot networking on macOS.