Re: Enumerating TLS protocol versions and ciphers supported by the peer

[Mark Hack <markhack@xxxxxxxxxxxx>]

Look at 

https://testssl.sh/

That is an openssl wrapper which enumerates ciphers and protocols ( and a whole lot more)


Hexcode  Cipher Suite Name (OpenSSL)       KeyExch.   Encryption  Bits     Cipher Suite Name (IANA/RFC)

-----------------------------------------------------------------------------------------------------------------------------

SSLv2  

SSLv3  

TLS 1  

TLS 1.1  

TLS 1.2  

 xc030   ECDHE-RSA-AES256-GCM-SHA384       ECDH 521   AESGCM      256      TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384              

 xc02f   ECDHE-RSA-AES128-GCM-SHA256       ECDH 521   AESGCM      128      TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256              

TLS 1.3  

 x1302   TLS_AES_256_GCM_SHA384            ECDH 521   AESGCM      256      TLS_AES_256_GCM_SHA384                             

 x1303   TLS_CHACHA20_POLY1305_SHA256      ECDH 521   ChaCha20    256      TLS_CHACHA20_POLY1305_SHA256                       

 x1301   TLS_AES_128_GCM_SHA256            ECDH 521   AESGCM      128      TLS_AES_128_GCM_SHA256

On Mon, 2021-12-06 at 15:06 +0000, Michael Wojcik wrote:

From: Dr. Matthias St. Pierre <Matthias.St.Pierre@xxxxxxxxx>

Sent: Monday, 6 December, 2021 07:53

To: Michael Wojcik <Michael.Wojcik@xxxxxxxxxxxxxx>; openssl-

"Comparable elegant" is underspecified.

(I guess, "Comparably elegant" would have been grammatically more

correct.)

I just meant that elegance is in the eye of the beholder.

Many people might agree that having a single command line return the list of what suites the server supports is elegant, at least for the user. Others prefer the original UNIX philosophy of simpler tools which are scripted to perform more complex operations; that's the testssl.sh approach, and it's more elegant in the sense of being composed in a visible (and modifiable) way from smaller pieces.

A command-line option to s_client to do this sort of server profiling is conceivable, but it would be a significant departure from what s_client does now, since it would conflict with some other options and would involve making multiple connections. That doesn't mean it shouldn't be implemented, necessarily, just that it's not parallel to most of the other things s_client options do.

-- 

Michael Wojcik