Do you have a VPS or server? How do you access it? You probably use SSH hopefully, right? Well before SSH there was something called telnet, telnet is a protocol on the internet(uses TCP/IP), telnet allows you to enter commands and execute them through the telnet program as if you were there. Telnet was developed roughly 48 years ago, it was great back in the day because cybersecurity wasn’t really an issue, but today it is a billion dollar market. One of the main flaws behind telnet today is that the traffic sent through telnet is not encrypted meaning that anyone watching your internet traffic can look through all the commands you run through telnet and may even see credentials you entered in. But good news, a new protocol was invented to take the place of telnet called SSH, data sent through SSH is encrypted fixing one of the main flaws behind telnet today.
Source for telnet: telnet