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Difference between Telnet and SSH

noviembre 30, 2019

Telnet and FTP are the TCP / IP protocols, application layers, connection-oriented that establish a connection to the server from the remote host to remotely access a system or transfer a file. These protocols can be used collaboratively, to access the FTP server transparently and therefore can be used to transfer files.

The common difference between Telnet and FTP that Telnet allows a client user to access the remote server to access its resources while FTP is used to transfer a file to the remote computer.

Comparative graph

Base for TelnetFTP comparison
BasicAllows a user to log in to the remote server.Allows a user to transfer a file to the remote computer.
Functions on the port number2321 and 20
SafetyYou may have some security issues.More secure than Telnet.
Remote access required to access system resources.Not necessarily necessary.

Definition of Telnet

Telnet a standard TCP / IP protocol to provide virtual terminal services standardized by ISO. In this protocol, the client-server first sets up a connection connection with the remote server and therefore the keys from the user's keyboard are transferred directly to the remote computer, which resembles the keystrokes transmitted by the keyboard connected to the machine. The result is also reported to the user by the remote machine. The process is considered transparent for users because it seems that the user is directly connected to the remote machine.

The remote machine is identified by the Telnet client software by defining its IP address or domain name. The process of accessing a remote machine can be complicated because the different operating system can be run on a different machine and even each machine and its operating system accept a combination of unique characters such as tokens. So here we are managing a heterogeneous system where we need a mechanism to find the type of computer and its specific terminal emulator that we want to access remotely.

Here Network Virtual Terminal (NVT) a universal interface defined by Telnet. With the help of NVT, the Telnet client software transforms characters (data or commands) from the local terminal into an NVT form and transmits them to the network. So the Telnet server translates the NVT form of data and commands into the module that can be accepted by the remote computer.

There are three standard services provided by Telnet. First, it provides interface to the remote system defined by Network Virtual Terminal (NVT) as mentioned above. The client program designed to use the standard interface and not need to understand the internal details of all possible remote systems. Second, Telnet provides a mechanism that allows the client and server to adjust options and a set of standard options. Finally, both ends of the connection are treated the same way by Telnet.

Definition of FTP

The FTP protocol (File Transfer Protocol) it is mainly used to transfer files from the local machine to the remote machine. The FTP client establishes the connection with the help of the TCP. The FTP server allows multiple clients to access the server simultaneously. Transferring a file to the remote machine can encounter some problems such as file name conventions, the directory structure and the representation of text and data in two different systems can be distinguished, which would make file transfer difficult.

FTP sets up two connections between hosts which makes it more efficient. The first connection is used for data transfer and others for information control (commands and responses). In the control connection, only one command line or response is transferred at a time. FTP uses port 21 for the control connection and port 20 for the data connection. In the entire FTP session, the control connection remains activated while the data connection is opened for file transfer and then closed when the file is transferred completely.

Key differences between Telnet and FTP

  1. Telnet allows a client user to access resources on a server remotely while FTP is used to copy a file from one machine to another.
  2. The Telnet protocol uses port number 23 for the connection. In contrast, FTP uses ports 21 and 20 respectively for control and data connections.
  3. Telnet does not use security measures, so it is not secure. As against, FTP uses encryption methods that implement security.
  4. In Telnet, the user must first log in to the remote computer and then perform any operation. On the contrary, in FTP the user does not have to access the remote device.

Conclusion

Telnet is used to access the remote machine to access its resources while FTP is a file transfer protocol used to transfer a file from one host to another on a network or the Internet.

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