openssh unix dev - Dec 2023 - Feature Request: new "Require Strict-KEX" c/s option

Hello,

since one currently (after the 9.6 release addressing terrapin with
strict-kex) cant be sure that strict KEX mode is negotiated (it depends
on the capabilities of the partner), and the mitigation for that is to
disable most modern/alternative ciphers and MAC modes - 

I would suggest you offer the option to enforce strict-kex mode as a server
config as well as a per-host config in the client config.

(obcredits: jssh has this setting).

Not sure if you also have precedence for warning on (console initiated)
connections which have no strict-kex, but that would be an additional
feature.

Gruss
Bernd
-- 
https://bernd.eckenfels.net