How to Configure Internet Sharing in macOS to Share Wi-Fi or Ethernet Connections

In environments where a dedicated wireless router is unavailable, during network troubleshooting in data rooms, or when staying in hotels that limit network access to a single authenticated physical port, a Mac can function as an ad-hoc software access point and router. Using the built-in Internet Sharing feature in macOS, you can route an active internet connection—originating from Ethernet, Thunderbolt, a USB modem, or iPhone USB tethering—to other devices via Wi-Fi or local wired links.

macOS manages this bridging through native Network Address Translation (NAT) and an automated Dynamic Host Configuration Protocol (DHCP) service, assigning local IP addresses to connected clients and forwarding traffic transparently.

Hardware and Adapter Rules for macOS Internet Sharing

Before configuring Internet Sharing, note the physical limitations of your Mac’s network hardware:

• No Dual-Channel Wi-Fi: The built-in wireless adapter on Mac hardware cannot receive Wi-Fi and broadcast a new Wi-Fi network simultaneously. To broadcast a Wi-Fi hotspot, your source connection must come from Ethernet, Thunderbolt, an iPhone USB cable, or a secondary external USB Wi-Fi adapter.
• Wi-Fi to Wired Sharing: If your Mac is connected to Wi-Fi, you can share that connection outbound to other computers, switches, or gaming consoles using an Ethernet cable or Thunderbolt Bridge.

Configuring Internet Sharing in macOS Sequoia and Sonoma

To set up and enable network sharing using the modern System Settings interface:

1. Connect your Mac to your primary internet source (such as an Ethernet cable connected via a USB-C or Thunderbolt adapter).
2. Click the Apple menu in the top-left corner and select System Settings.
3. Navigate to the General category in the sidebar and click Sharing.
4. Scroll down to the Internet Sharing row. Click the small Information (i) button on the right side before turning the service on.

Configuring Input Sources and Target Interfaces

In the configuration panel that appears:

1. In the Share your connection from dropdown menu, select the network adapter providing internet connectivity (such as Ethernet Adapter, Thunderbolt Ethernet, or iPhone USB).
2. In the To devices using checklist below, tick the box for the interface you want to broadcast or share through (for example, Wi-Fi).
3. If sharing through Wi-Fi, click the Wi-Fi Options button at the bottom of the dialogue.

Securing Your Wireless Hotspot with Wi-Fi Options

Do not broadcast an open wireless network. Protect the connection to prevent unauthorised bandwidth consumption:

1. Enter a recognisable name in the Network Name (SSID) field.
2. Leave the Channel setting on default unless operating in an environment with high wireless interference.
3. Click the Security dropdown menu and select WPA2/WPA3 Personal (or WPA2 Personal for compatibility with older legacy equipment).
4. Enter a strong network password in the Password and Verify fields.
5. Click OK to save the wireless security parameters.

Enabling the Connection and Verifying Client Leases

Once parameters are defined:

1. Click Done to exit the configuration sheet.
2. Switch the toggle switch next to Internet Sharing to the On position.
3. A system confirmation prompt will appear explaining that enabling Internet Sharing may disrupt existing local network configurations. Click Start to confirm.

Your Mac immediately initialises its virtual software router. The Wi-Fi menu bar icon changes to an upward-pointing arrow inside a fan shape, signifying active hotspot broadcasting. On connecting client devices (such as smartphones, tablets, or laptops), select your configured SSID and enter the password.

To inspect active DHCP leases issued to connected clients, open Terminal on your Mac and view the system bootpd lease log:

cat /var/db/dhcpd_leases

This displays the client MAC addresses, assigned local IP addresses (typically within the 192.168.2.x range), and lease expiration timestamps.

Preventing Sleep Mode Disconnections

By default, macOS will enter system sleep when idle on battery power, terminating the active software router and dropping connected client sessions. To prevent this when sharing connections:

1. Open System Settings > Energy (or Displays on desktop Mac models).
2. Ensure Prevent automatic sleeping when the display is off is toggled on when connected to a power adapter.
3. Always keep the Mac plugged into mains power during prolonged Internet Sharing sessions.