-iTCP -sTCP:LISTEN - Shows only network files with TCP state LISTEN.ĬOMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME.-p - Do not resolve hostnames, show numerical addresses.-n - It does not convert port numbers to port names.You can imagine a socket as a file that writes to the network.Ģ) Next, get a list of all listening TCP ports with the lsof type: sudo lsof -nP -iTCP -sTCP:LISTENįollowing are some of the options which are used: It provides information about files opened by the processes. Step 3 - Check the Listening Ports with lsofġ) The lsof is a powerful command-line utility. State Recv-Q Send-Q Local Address:Port Peer Address:Port The output is the same as the one reported by netstat: Output You can get a list of all listening ports with ss by using the following command: sudo ss -tunlp As the command options are mainly the same, the transition from netstat to ss is not difficult. It lacks few netstat features but exposes more TCP states and is faster. Step 2 - Check the Listening Ports with ssġ) Now ss has replaced netstat. Still, it is one of the most used commands to check the network connections. Netstat is obsolete and is replaced by ss and ip. It is also possible to filter the list based on PID, protocol, state. If the output is empty, then it simply means that nothing is listening on that particular port. The output shows that the port is being used by SSH server: Output You will type: sudo netstat -tnlp | grep :22 For example, if you want to find what process listens on TCP port 22. PID/Program name - PID and the name of the process.Ģ) If you want to filter the results, use the grep command.Local Address - The IP Address and Port Number on which the process listens.Proto - Protocol that is used by the socket.Udp 0 0 0.0.0.0:68 0.0.0.0:* 966/dhclientįollowing are some important columns in our case: Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name You need to run the command as a root user or with sudo privileges to get the information. -p - It shows the PID and the name of the listener’s process.-n - Show the numerical addresses instead of resolving the hosts.The different options of this command and their meaning is listed below:
Step 1 - Check the Listening Ports with netstatġ) netstat is a command-line tool that provides information about the network connections.Īll the TCP or UDP ports that are being listened on along with the services using ports and the socket status can be listed using the following command: sudo netstat -tunlp We will also address some of the FAQs related to Listening Ports. In this tutorial, you will learn how to check for Listening Ports in Linux.
Then, the latter will fail to start as the HTTP and HTTPS ports are already in use. If you are running an Apache web server that listens on both ports 80 and 443 and later you are trying to install NGINX. There can be only one application listening to a specific port on the same IP address. Generally, the open port is a network port that accepts incoming packets from remote locations. Each listening port is either open or closed using a firewall. While dealing with network connectivity or application-specific issues, firstly you should check which ports are in use and which application is running on that specific port.Ī listening port is a network port on which an application or the process listens. Let’s briefly understand - What is Listening Port? Before we begin talking about how to check for Listening Ports in Linux.
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