20 Netstat Commands for Linux Network Management

netstat (network statistics) is a command line tool for monitoring network connections both incoming and outgoing as well as viewing routing tables, interface statistics etc. netstat is available on all Unix-like Operating Systems and also available on Windows OS as well. It is very useful in terms of network troubleshooting and performance measurement. netstat is one of the most basic network service debugging tools, telling you what ports are open and whether any programs are listening on ports.

This tool is very important and much useful for Linux network administrators as well as system administrators to monitor and troubleshoot their network related problems and determine network traffic performance. This article shows usages of netstat command with their examples which may be useful in daily operation.

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1. Listing all the LISTENING Ports of TCP and UDP connections

Listing all ports (both TCP and UDP) using netstat -a option.

2. Listing TCP Ports connections

Listing only TCP (Transmission Control Protocol) port connections using netstat -at.

3. Listing UDP Ports connections

Listing only UDP (User Datagram Protocol ) port connections using netstat -au.

4. Listing all LISTENING Connections

Listing all active listening ports connections with netstat -l.

5. Listing all TCP Listening Ports

Listing all active listening TCP ports by using option netstat -lt.

6. Listing all UDP Listening Ports

Listing all active listening UDP ports by using option netstat -lu.

7. Listing all UNIX Listening Ports

Listing all active UNIX listening ports using netstat -lx.

8. Showing Statistics by Protocol

Displays statistics by protocol. By default, statistics are shown for the TCP, UDP, ICMP, and IP protocols. The -s parameter can be used to specify a set of protocols.

9. Showing Statistics by TCP Protocol

Showing statistics of only TCP protocol by using option netstat -st.

10. Showing Statistics by UDP Protocol

11. Displaying Service name with PID

Displaying service name with their PID number, using option netstat -tp will display “PID/Program Name”.

12. Displaying Promiscuous Mode

Displaying Promiscuous mode with -ac switch, netstat print the selected information or refresh screen every five second. Default screen refresh in every second.

13. Displaying Kernel IP routing

Display Kernel IP routing table with netstat and route command.

14. Showing Network Interface Transactions

Showing network interface packet transactions including both transferring and receiving packets with MTU size.

15. Showing Kernel Interface Table

Showing Kernel interface table, similar to ifconfig command.

16. Displaying IPv4 and IPv6 Information

Displays multicast group membership information for both IPv4 and IPv6.

17. Print Netstat Information Continuously

To get netstat information every few second, then use the following command, it will print netstat information continuously, say every few seconds.

18. Finding non supportive Address

Finding un-configured address families with some useful information.

19. Finding Listening Programs

Find out how many listening programs running on a port.

20. Displaying RAW Network Statistics

That’s it, If you are looking for more information and options about netstat command, refer netstat manual docs or use man netstat command to know all the information. If we’ve missed anything in the list, please inform us using our comment section below. So, we could keep updating this list based on your comments.

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