3 Ways to Check if a Port is Open on a Remote Linux System

In this article, we will show you how to check which ports are open on a remote Linux system using three methods.

This can be done with the following Linux commands.

nc: Netcat is a simple Unix utility that reads and writes data over network connections using the TCP or UDP protocol.
nmap: Nmap (“Network Mapper”) is an open source tool for network exploration and security auditing. It was designed to quickly scan large networks.
telnet: The telnet command is used to communicate interactively with another host using the TELNET protocol.

How to check if a port is open on a remote Linux system using nc (netcat) command?

nc stands for netcat.

Netcat is a simple Unix utility that reads and writes data over network connections using the TCP or UDP protocol. It is designed to be a reliable “internal” tool that can be used directly or easily manipulated by other programs and scripts. At the same time, it is a multi-functional network debugging and exploration tool because it can create almost any type of connection you need and has some interesting built-in features.

Netcat has three main modes of operation. These are connect mode, listen mode and tunnel mode.

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