Telnet

The Telecommunication Network protocol allows users to remotely access and control devices over a network, typically using port 23. It was widely used for remote administration of systems before being largely replaced by SSH due to security concerns about sending the data in plain text, making it vulnerable to interception.

Interaction with the protocol

• Install

sudo apt install telnet

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• Connect using the protocol

sudo telnet $ip $port
telnet: \>      #Text based interface
telnet: \> exit #Close connection

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• Interact with other protocols

#Example
sudo telnet $ip 80 #We connect to HTTP service

#We send a petition
GET / HTTP/1.1
host: telnet      #After finishing, hit enter twice to send

If the host isn't specified, we will get an error