Question

How can I convince that id_dsa is not stored in ~/.ssh when connecting to one particular host.

The obvious question is why. The answer is this key is more sensitive and needs to be password protected while the other is used for automation.

While this is not a programming problem, I would not be surprised to learn this requires a programming solution.

Answer 1

In your .ssh/config, set something like:

Host somehost
     IdentityFile /path/to/extra_secret_key

I have one host that has IdentityFile set to ~/.ssh/iddsa_aux, but the parameter should accept any path name.