Every admin knows as to use
telnet to test remote port connectivity. But did you know that you can use this command in more ‘creative’ manners ?
For example to send mail in a fully manual mode:
# telnet localhost smtp Connected to localhost. Escape character is '^]'. 220 sd-35049.dedibox.fr ESMTP Exim 4.72 Mon, 16 Jan 2012 12:56:06 +0100 HELO sd-35049.dedibox.fr 250 sd-35049.dedibox.fr Hello localhost [::1] mail from: email@example.com 250 OK rcpt to: firstname.lastname@example.org 250 Accepted data 354 Enter message, ending with "." on a line by itself Hey genius buddy This is a test! . 250 OK id=1cT5uM-0001oK-Dm quit 221 sd-35049.dedibox.fr closing connection Connection closed by foreign host.