74 lines
1.4 KiB
Markdown
74 lines
1.4 KiB
Markdown
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---
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title: "e-mail"
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tags: [ "data", "smtp" ]
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---
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This is bare-bones, original, primitive e-mail.
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Install `opensmtpd` (or similar), then `ncat` or `nc` or `netcat` (this mysterious cat has many names).
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Start the `opensmtpd` service, then use netcat to speak with the mail-daemon:
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```
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nc localhost 25
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```
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The computer should respond with code `220`, which means 'I am listening'.
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> 220 hex ESMTP OpenSMTPD
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```
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HELO gmail.com
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```
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You say `HELO` and say where you are coming from.
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The `smtpd` will not check, so I am going to lie to it.
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Mail servers are easily impressed, so it will be pleased to meet you.
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> 250 hex Hello gmail.com [::1], pleased to meet you
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```
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MAIL FROM: <admin@gmail.com>
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```
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All the mail commands start with 4 bytes, because it's easier for admins to program.
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Tell the mail daemon who you are in this format.
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> 250 2.0.0 Ok
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Then tell it who you're sending to.
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```
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RCPT TO: <www@dmz.rs>
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```
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> 250 2.1.5 Destination address valid: Recipient ok
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Finally, tell it that you want to send `DATA`.
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```
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DATA
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```
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> 354 Enter mail, end with "." on a line by itself
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```
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Subject: turn off server please
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very urgent
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.
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```
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> 250 2.0.0 73864a49 Message accepted for delivery
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You will find the email under `/var/spool` or `/var/mail` or similar.
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If unsure, just take a part of your email, like `FRAGMENT="turn off server please"`, then `grep` for it:
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```bash
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sudo grep -r $FRAGMENT /var/spool/*
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```
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