Re: How to find out if SMTP mailserver supports STARTTLS or (only) SSL/TLS ?
"Watson, Patrick" <[email protected]>
| Newsgroups | gmane.comp.security.nmap.devel |
|---|---|
| Message-ID | <[email protected]> |
There are 4 possible states: Service STARTTLS Meaning smtp not present TLS is not supported at all; everything is plain text smtp present TLS is only supported via STARTTLS. The connection begins unencrypted. This is called “Opportunistic TLS” ssl/smtp not present TLS is only supported at the connection level, which begins encrypted. STARTTLS is not supported ssl/smtp present TLS is supported at the connection level, which begins encrypted. You can also issue a STARTTLS command to turn on TLS, but that doesn’t make any sense because it’s already on. Thus, you probably won’t see this often in real life. -- Patrick From: Ben Stover <[email protected]> Date: Thursday, October 26, 2017 at 1:41 AM To: "Watson, Patrick" <[email protected]> Cc: nmap MailList <[email protected]> Subject: Re: How to find out if SMTP mailserver supports STARTTLS or (only) SSL/TLS ? 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 gmail’s SMTP as an example below, I’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 ( https://urldefense.proofpoint.com/v2/url?u=http-3A__nmap.org&d=DwIGaQ&c=gJN2jf8AyP5Q6Np0yWY19w&r=kb9QwPhIkTE-L66gFI1opw&m=s8JxJ-fU_qbm7YH4oBQ8uMUgZAV8ET5iZIDqyV98gvo&s=b0y1xBqw7py4alngGsxcNNnZhSjLufkihM2OWI33OOw&e= ) 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://urldefense.proofpoint.com/v2/url?u=https-3A__www.google.com_search-3FbtnI-26q-3DRFC-2B5321&d=DwIGaQ&c=gJN2jf8AyP5Q6Np0yWY19w&r=kb9QwPhIkTE-L66gFI1opw&m=s8JxJ-fU_qbm7YH4oBQ8uMUgZAV8ET5iZIDqyV98gvo&s=stH4noXGzfFQQu-2spT_vqbo9Qc8yy5lKZ9r0H2X9j8&e= 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://urldefense.proofpoint.com/v2/url?u=https-3A__www.google.com_search-3FbtnI-26q-3DRFC-2B5321&d=DwIGaQ&c=gJN2jf8AyP5Q6Np0yWY19w&r=kb9QwPhIkTE-L66gFI1opw&m=s8JxJ-fU_qbm7YH4oBQ8uMUgZAV8ET5iZIDqyV98gvo&s=stH4noXGzfFQQu-2spT_vqbo9Qc8yy5lKZ9r0H2X9j8&e= b129sm3894212ywe.99 - gsmtp Service Info: Host: smtp.gmail.com Service detection performed. Please report any incorrect results at https://urldefense.proofpoint.com/v2/url?u=http-3A__nmap.org_submit_&d=DwIGaQ&c=gJN2jf8AyP5Q6Np0yWY19w&r=kb9QwPhIkTE-L66gFI1opw&m=s8JxJ-fU_qbm7YH4oBQ8uMUgZAV8ET5iZIDqyV98gvo&s=xj0gIqAn0WHjtYs7IMh9n8ML6znv5PNfOegwUl3GWHI&e= . Nmap done: 1 IP address (1 host up) scanned in 19.84 seconds -- Patrick _______________________________________________ Sent through the dev mailing list https://nmap.org/mailman/listinfo/dev Archived at http://seclists.org/nmap-dev/