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How To Identify the Program Listening on a Port in Ubuntu

Ubuntu 10

In the world of networking, ports are crucial for establishing connections between different applications. However, there may be times when you need to identify which program is using a specific port. In this article, we will delve into various ways to identify the program listening on a port in Ubuntu using command-line tools such as lsof, netstat, ss, and socklist.

Quick Answer

To identify the program listening on a port in Ubuntu, you can use command-line tools such as lsof, netstat, ss, and socklist. These tools provide information about open files, network connections, and socket statistics, allowing you to determine which program is using a specific port.

Using the lsof Command

lsof stands for ‘List Open Files’. It’s a powerful command-line tool that provides information about files that are opened by processes. To use lsof to identify the program listening on a specific port, say port 8000, open your terminal and type the following command:

lsof -i :8000

In this command, -i selects the listing of files any of whose Internet address matches :8000. If you don’t see any results, try running the command with sudo since you might not have permission to certain processes.

Using the netstat Command

netstat is another command-line tool that can be used to display network connections, routing tables, interface statistics, and more. To identify the program listening on a specific port using netstat, type the following command in your terminal:

netstat -peanut | grep ":8000 "

In this command, the options -peanut break down as follows:

  • -p shows the PID and name of the program to which each socket belongs.
  • -e provides additional information.
  • -a displays both listening and non-listening sockets.
  • -n shows numerical addresses instead of trying to determine symbolic host, port, or user names.
  • -t displays TCP connections.

The grep command is used to filter out the output for port 8000.

Using the ss Command

ss is a utility to investigate sockets, and it’s a part of the iproute2 package. It’s used to dump socket statistics and displays information in a similar manner to netstat. To use ss to identify the program listening on a specific port, type the following command in your terminal:

ss -nlp | grep 8000

In this command, the options -nlp break down as follows:

  • -n shows numerical addresses instead of trying to determine symbolic host, port, or user names.
  • -l displays only listening sockets.
  • -p shows the process using the socket.

Using the socklist Command

The socklist command is part of the procinfo package, and it displays a list of open sockets, showing the type, port, and owning process ID. To use socklist, type the following command in your terminal:

sudo socklist

Look for the entry with port 8000 to find the program listening on that port.

Conclusion

In conclusion, identifying the program listening on a specific port in Ubuntu can be accomplished using various command-line tools such as lsof, netstat, ss, and socklist. Understanding how to use these tools can be incredibly helpful in managing and troubleshooting your network connections.

How can I identify the program listening on a port in Ubuntu?

To identify the program listening on a port in Ubuntu, you can use command-line tools such as lsof, netstat, ss, or socklist. These tools provide information about the processes and sockets associated with specific ports.

How do I use the `lsof` command to identify the program listening on a port?

To use the lsof command, open your terminal and type lsof -i :<port number>. For example, to identify the program listening on port 8000, you would type lsof -i :8000. If you don’t see any results, try running the command with sudo.

How can I use the `netstat` command to identify the program listening on a port?

To use the netstat command, type netstat -peanut | grep ":<port number>" in your terminal. Replace <port number> with the actual port number you want to check. For example, to identify the program listening on port 8000, you would type netstat -peanut | grep ":8000 ". This command will display the PID and name of the program associated with the specified port.

What is the `ss` command and how can I use it to identify the program listening on a port?

The ss command is a utility used to investigate sockets and is part of the iproute2 package. To identify the program listening on a port using ss, type ss -nlp | grep <port number> in your terminal. Replace <port number> with the actual port number you want to check. For example, to identify the program listening on port 8000, you would type ss -nlp | grep 8000. This command will display the process using the socket on the specified port.

How can I use the `socklist` command to identify the program listening on a port?

The socklist command is part of the procinfo package and displays a list of open sockets, including the port and owning process ID. To use socklist, type sudo socklist in your terminal. Look for the entry with the port number you want to check to find the program listening on that port. For example, if you want to identify the program listening on port 8000, you would look for the entry with port 8000 in the output of socklist.

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