Hi Heikki,

I have one comment about the suggestion to indicate that 
draft-ietf-tls-keylogfile is a better option.

That spec says actually the following:

   This format is intended for use in
   systems where TLS only protects test data.  While the access that
   this information provides to TLS connections can be useful for
   diagnosing problems while developing systems, this mechanism MUST NOT
   be used in a production system.

I'm not quite sure we can recommend this mechanism here.

Cheers,
Med

De : Heikki Vatiainen <h...@radiatorsoftware.com>
Envoyé : lundi 25 novembre 2024 19:18
À : opsawg <opsawg@ietf.org>
Objet : [OPSAWG]draft-ietf-opsawg-tacacs-tls13: Debugging TACACS+ over TLS


Would it be possible to add some text about troubleshooting TACACS+ when TLS is 
enabled? More exactly, add a reminder that TLS keylog  
https://datatracker.ietf.org/doc/draft-ietf-tls-keylogfile/ is a better option 
than:

- trying to enable NULL encryption, authentication and integrity only, ciphers 
for TLSv1.3 (see RFC 9150, supported by WolfSSL and OpenSSL 3.4); or
- switching to non-TLS TACACS+ connections just because of troubleshooting

Any of the above alternatives would likely require configuration changes on the 
TACACS+ server and client side which may affect more connections than 
necessary. After the troubleshooting is done, any changes to TLS settings would 
also need to be reverted. This may be easy to forget leaving the system in 
insecure state.

The reason why debugging is done may also relate to the TLS handshake itself in 
which case any changes to TLS settings may make the debugging effort useless. 
I.e., the attempt to observe the system changes the system behaviour.

To provide some background, I work on AAA software named Radiator that has 
supported TACACS+ for 20+ years. From what we see, Wireshark, as an example, is 
often used to debug TACACS+. It's well-known, supports TACACS+ well and very 
importantly, provides a neutral third party view of what's going on between the 
client and server. Because Wireshark also supports TLS keylog, it will likely 
continue to be a very important tool when TACACS+ runs over TLS.

Thanks to authors working on this! Please excuse me for being a bit late for 
the party.

--
Heikki Vatiainen
h...@radiatorsoftware.com<mailto:h...@radiatorsoftware.com>
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