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Internet Technologies/Telnet

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Telnet is a protocol designed to remotely access computers in a client-server fashion. Telnet is inherently insecure, as the data passed from the client to the server or vice-versa is not encrypted. For connections through insecure networks (such as the Internet), SSH (Secured SHell), should be used so all communications between the client and server are encrypted.

Examples

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Test if the HTTP port is open and its service listening

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telnet localhost 80

Send an email

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telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.localdomain.
Escape character is '^]'.
220 smtp.mydomain.com
mail from:<[email protected]>
250 2.1.0 <[email protected]>... Sender ok
rcpt to:<[email protected]>
250 2.1.5 <[email protected]>... Recipient ok
data
354 Enter mail, end with "." on a line by itself
Let's meet
.
250 2.0.0 n514OvkN019941 Message accepted for delivery
quit
221 2.0.0 smtp.mydomain.com closing connection
Connection closed by foreign host.