Port scanning with Netcat (connect)

Since Netcat is a network socket connection and management utility, it can easily be transformed into a TCP port-scanning utility. This specific recipe demonstrates how we can use Netcat to perform a TCP connect scan.

Getting ready

To use Netcat to perform a full connect scan, you will need to have a remote system that is running network services over TCP. In the examples provided, an instance of Metasploitable2 is used to perform this task. For more information on how to set up Metasploitable2, refer to Chapter 1, Getting Started.

How to do it…

Netcat is an extremely useful, multipurpose networking utility that can be used for a plethora of purposes. One effective use of Netcat is to perform port scans:

1. To identify the usage options, Netcat (nc) should be called with the -h option, as follows:

2. As indicated by the usage output, the -z option can effectively be used for scanning. To scan the TCP port 80 on a target system, we use the -n option to indicate that...