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Netstat (Network Statistics) is a command-line tool that displays network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. It is a powerful utility for network troubleshooting and monitoring. Below, we’ll explore how to use netstat effectively, along with practical commands and examples.
You Should Know: Essential Netstat Commands
1. Display All Active Connections
To list all active connections, use:
netstat -a
This command shows both listening and non-listening sockets.
2. Show Listening Ports
To display only the ports that are listening for incoming connections:
netstat -l
3. Display TCP and UDP Connections
To show only TCP connections:
netstat -at
For UDP connections:
netstat -au
4. Show Process ID and Program Name
To display the process ID (PID) and program name associated with each connection:
netstat -p
5. Display Statistics by Protocol
To view statistics for TCP, UDP, ICMP, and IP protocols:
netstat -s
6. Check Routing Table
To display the kernel routing table:
netstat -r
7. Show Network Interface Information
To display information about network interfaces:
netstat -i
8. Continuous Monitoring
To refresh the netstat output every few seconds (e.g., every 2 seconds):
netstat -c 2
Practical Examples
- Check for Open Ports
If you suspect unauthorized open ports, use:
netstat -tuln
This lists all listening TCP and UDP ports.
- Identify Established Connections
To see active connections:
netstat -an | grep ESTABLISHED
- Kill a Process Using a Specific Port
If you find an unwanted process using a port, identify the PID with:netstat -tulnp | grep :<port_number>
Then, terminate the process using:
kill -9 <PID>
What Undercode Say
Netstat is an indispensable tool for network administrators and cybersecurity professionals. It provides deep insights into network activity, helping you detect suspicious connections, troubleshoot issues, and optimize performance. Mastering netstat commands can significantly enhance your ability to manage and secure networks. For further reading, check out these resources:
By combining netstat with other tools like ss, lsof, and nmap, you can build a robust network monitoring and security strategy. Keep practicing these commands to become proficient in network analysis and troubleshooting.
References:
Reported By: Chuckkeith How – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
