Re: How to find out if SMTP mailserver supports STARTTLS or (only) SSL/TLS ?

[Ben Stover via dev <dev () nmap org>]

Hello Patrick,

thank you for the information.

Just to clarify:

If in the list of reported smtp-commands the tag "STARTTLS" appears then (only) the STARTTLS protocol is valid on this 
port.
If the tag STARTTLS is NOT listed in the output of smtp-commands then (only) SSL/TLS is supported

Correct?

Ben


--Original Message Text---
From: Watson, Patrick
Date: Mon, 23 Oct 2017 16:59:10 +0000

Combining the smtp-commands script with the normal version scanning, you can figure this out. 

Using gmailâ¬"s SMTP as an example below, Iâ¬"ve highlighted in yellow the parts you want to pay attention to. Port 465 
uses TLS from the start (aka SMTPS). Port 587 uses 
STARTTLS to switch from plain text to TLS after connecting. 

# nmap -sV -Pn -p 465,587 --version-intensity 8 --script smtp-commands.nse smtp.gmail.com 

Starting Nmap 6.47 ( http://nmap.org ) at 2017-10-23 16:49 UTC 

Nmap scan report for smtp.gmail.com (74.125.136.108) 

Host is up (0.012s latency). 

Other addresses for smtp.gmail.com (not scanned): 74.125.136.109 

PORT STATE SERVICE VERSION 

465/tcp open ssl/smtp Google gsmtp 

| smtp-commands: smtp.gmail.com at your service, [73.237.100.36], SIZE 35882577, 8BITMIME, AUTH LOGIN PLAIN XOAUTH2 
PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH, 
ENHANCEDSTATUSCODES, PIPELINING, CHUNKING, SMTPUTF8, 

|_ 2.0.0 https://www.google.com/search?btnI&q=RFC+5321 j14sm454180ywg.74 - gsmtp 

587/tcp open smtp Google gsmtp 

| smtp-commands: smtp.gmail.com at your service, [73.237.100.36], SIZE 35882577, 8BITMIME, STARTTLS, 
ENHANCEDSTATUSCODES, PIPELINING, CHUNKING, SMTPUTF8, 

|_ 2.0.0 https://www.google.com/search?btnI&q=RFC+5321 b129sm3894212ywe.99 - gsmtp 

Service Info: Host: smtp.gmail.com 

Service detection performed. Please report any incorrect results at http://nmap.org/submit/ . 

Nmap done: 1 IP address (1 host up) scanned in 19.84 seconds 

-- Patrick 




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