Monitoring network traffic is crucial for maintaining the security and performance of your systems. For macOS users, understanding how to monitor network traffic can help in diagnosing connectivity issues, detecting unauthorized access, and optimizing network performance. This article will guide you through the process of monitoring network traffic on macOS using built-in tools and third-party applications.

Examples:

1. Using Activity Monitor:

   • Open Activity Monitor from the Applications > Utilities folder.
   • Click on the "Network" tab to view real-time network usage.
   • This tab displays data sent and received, packets sent and received, and other relevant network statistics.

2. Using Terminal and nettop:

   • Open the Terminal application.
   • Run the command nettop to display a detailed view of network activity.
   • The nettop command provides a real-time, text-based interface that shows the network connections and bandwidth usage for each process.

   nettop

3. Using tcpdump:

   • Open Terminal.
   • Run the tcpdump command to capture and analyze network packets.
   • For example, to capture packets on the default network interface:

   sudo tcpdump -i en0

   • To save the captured packets to a file for later analysis:

   sudo tcpdump -i en0 -w capture.pcap

4. Using Wireshark:

   • Download and install Wireshark from Wireshark's official website.
   • Open Wireshark and select the network interface you want to monitor.
   • Click "Start" to begin capturing network traffic.
   • Wireshark provides a comprehensive graphical interface for analyzing network packets in detail.

5. Using Little Snitch:

   • Download and install Little Snitch from Little Snitch's official website.
   • Little Snitch allows you to monitor and control outgoing network connections.
   • It provides real-time notifications and detailed logs of network activity.