SMTP

Enumeration

Configuration

cat /etc/postfix/main.cf | grep -v "#" | sed -r "/^\s*$/d"

Commands

AUTH PLAIN # AUTH is a service extension used to authenticate the client.
HELO # The client logs in with its computer name and thus starts the session.
MAIL FROM # The client names the email sender.
RCPT TO # The client names the email recipient.
DATA # The client initiates the transmission of the email.
RSET # The client aborts the initiated transmission but keeps the connection between client and server.
VRFY # The client checks if a mailbox is available for message transfer.
EXPN # The client also checks if a mailbox is available for messaging with this command.
NOOP # The client requests a response from the server to prevent disconnection due to time-out.
QUIT # The client terminates the session.

Authentication

telnet 10.10.10.10 25

List existing users

VRFY root

smtp-user-enum -m VRFY -U names.txt "10.10.10.10" 25