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...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