Telnet

telnet(1) is a text-based communication protocol and virtual terminal.

Historically, telnet(1) was used in a similar manner to modern SSH.

Contents

  1. Telnet
    1. Installation
    2. Configuration
    3. Usage
      1. Star Wars
      2. SMTP

Installation

Configuration

Usage

Star Wars

telnet towel.blinkenlights.nl

SMTP

To use telnet(1) for SMTP, try running telnet smtp.example.com 25. This opens a REPL, which is annotated here with arrows denoting user input (->), server response (<-), and local client messages (-). 

 -  Trying smtp.example.com...
 -  Connected smtp.example.com.
 -  Escape character is '^]'.
<-  220 smtphostname ESMTP Postfix
 -> ehlo smtphostname
<-  250-smtphostname
<-  250-PIPELINING
<-  250-SIZE 10240000
<-  250-VRFY
<-  250-ETRN
<-  250-ENHANCEDSTATUSCODES
<-  250-8BITMIME
<-  250-DSN
<-  250-SMTPUTF8
<-  250-CHUNKING
 -> mail from: [email protected]
<-  250 2.1.0 Ok
 -> rcpt to: [email protected]
<-  250 2.1.5 Ok
 -> data
<-  354 End data with <CR><LF>.<CR><LF>
 -> This is the body of an email.
 -> Exit this REPL by submitting a line that only contains a period.
 -> .
<-  250 2.0.0 Ok: queued as 0123456789ab
 -> quit
<-  221 2.0.0 Bye
 -  Connection closed by foreign host.

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