Installation and all commands are based on Ubuntu 24.04.

installation

Linux environment

sudo apt update
sudo apt install netcat

Windows environment (11)
https://nmap.org/ncat/

Ncat - Netcat for the 21st Century

Download Reference Guide Book Docs Zenmap GUI In the Movies . . \`-”’”-’/ } 6 6 { ==. Y ,== /^^^\ . / \ ) ( )-( )/ _ -""---""--- / / Ncat \_/ ( ____ \_.=|____E Ncat is a feature-packed networking utility which reads and writes data across networks from the

nmap.org

Download the installation file from the above site and install.

Command used

#Linux
nc {host} {port}

In the problem description in CTF:
nc 123.456.789 1234
If it is written like this, you can connect to nc and solve it.