Ways to find out which process is listening on a specific port

Date Tags linux

Abstract

There are at least three ways to find out which process is listening on a particular port.

A port is a logical object that represents a communication endpoint and is associated with a process or service in the operating system.

In this article, we will show three different ways to find the process listening on a specific port in Linux.

Contents

Using the netstat command

The netstat (network statistics) command is used to display information about network connections, routing tables, interface statistics, and beyond. It is available on all Unix-like operating systems, including Linux, as well as on Windows.

If netstat is not installed by default, use the following command to install it:

sudo yum install net-tools #RHEL/CentOS
sudo apt install net-tools #Debian/Ubuntu
sudo dnf install net-tools #Fedora 22+

Once installed, you can use netstat along with grep to find the process listening on a specific port on Linux like so:

sudo netstat -ltnp | grep -w ':80'

The above command uses the following options:

  • l instructs netstat to show only listening sockets.
  • t - indicates the display of tcp connections.
  • n - indicates that it is necessary to show ip-addresses.
  • p - allows you to show the process ID and process name.
  • grep -w - matches exact string (':80').

Using the lsof command

The lsof (LiSt Open Files) command is used to list all open files on a Linux system. To install it on your system, enter the command below.

sudo yum install lsof #RHEL/CentOS
sudo apt install lsof #Debian/Ubuntu
sudo dnf install lsof #Fedora 22+

To find the process listening on a specific port, type:

sudo lsof -i :80

The above command uses the following options:

  • i lists IP sockets.

Using the fuser command

fuser shows the PID of processes using specified files or filesystems on Linux.

You can install it like this:

sudo yum install psmisc #RHEL/CentOS
sudo apt install psmisc #Debian/Ubuntu
sudo dnf install psmisc #Fedora 22+

You can find the process listening on a specific port by running the command below:

sudo fuser 22/tcp

Then find the process name using the PID number, with the ps command:

sudo ps -p 177

The above command uses the following options:

  • p specific process PID

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