Idea of Protocol – Telnet, SSH, FTP



Telnet is a terminal emulation protocol that enables a user at one site to simulate a session on a remote host. It does this by translating keystrokes from the user’s terminal to instructions recognized by the remote host, and then carrying the output back to the user’s terminal and displaying it in a format native to the remote host. This service is transparent; it gives users the impression that their terminals are directly attached to the remote host.



Secure Shell (SSH) is a protocol that enables a user or application to log on to another computer over a network, execute commands, and manage files. It provides strong authentication methods and secure communications over insecure channels. It is a more secure version of remote connection programs that transmit passwords unencrypted, such as Telnet. With the SSH slogin command, the entire login session, including the password, is encrypted and protected against attack.


SSH Clients

There are many popular SSH clients, though not all clients work with all operating systems.

1. Operating System: Windows

Available SSH Client(s): PuTTY, AbsoluteTelnet, CopSSH, eSSH Client, OpenSSH, SFTPPlus, Tera Term, WinSCP, XShell

2. Operating System: Mac®OS X

Available SSH Client(s): Dropbear, eSSH Client, lsh

3. Operating System: Linux®/UNIX

Available SSH Client(s): PuTTY, Dropbear, eSSH Client, lsh, SFTPPlus, SSH Tectia



File Transfer Protocol (FTP) is a protocol used to upload or download files to or from an FTP file server. The FTP protocol predates current web protocols such as HTTP, but unlike other legacy Internet protocols that have been superseded by HTTP, FTP remains in use because it provides much more efficient transfer of large amounts of data between systems. FTP servers may require users to log on, or they may allow anonymous connections.


FTP Client-side Issues

Most of these issues can be addressed and fixed within the FTP client’s configuration settings. Possible issues include:

  • The client is not set to receive/send on the correct ports.
  • The client is trying to establish an FTP connection with the wrong IP address.
  • The client’s firewall is too strict, and does not allow exceptions through.
  • Sometimes, clients send an FTP site as a hyperlink. If your workplace does not

allow the use of browsers as FTP clients, and prefers to instead use a standalone client, then this hyperlink will not work if the user clicks on it.



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