Netstat is a powerful command-line tool that provides detailed information about network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. It is essential for network troubleshooting and monitoring. While Netstat is commonly associated with Unix-like systems, it is also available on macOS, making it a valuable tool for Apple users.

In this article, we will explore how to use Netstat on macOS, providing practical examples and commands to help you understand and leverage this tool effectively.

Examples:

1. Display All Active Connections:
To display all active network connections, open the Terminal application on your macOS and run the following command:

   netstat -an

This command lists all active connections along with their respective IP addresses and port numbers.

2. Display Listening Ports:
To see which ports your macOS system is listening on, use the following command:

   netstat -an | grep LISTEN

This command filters the output to show only the ports that are in the LISTEN state.

3. Show Routing Table:
To display the routing table, which shows how data packets are directed through the network, use:

   netstat -nr

The -n flag ensures that the addresses are shown in numeric format, and the -r flag displays the routing table.

4. Display Interface Statistics:
To view statistics for all network interfaces, run:

   netstat -i

This command provides information about the packets received and transmitted on each network interface.

5. Monitor Network Traffic:
To continuously monitor network traffic, you can use the following command:

   netstat -w 1

The -w flag followed by a number specifies the interval (in seconds) at which the statistics should be updated.

6. Display Protocol Statistics:
To get detailed statistics for specific protocols (e.g., TCP, UDP), use:

   netstat -s

This command provides a summary of statistics for each protocol.