Parece que a sua verdadeira pergunta está no final:
How does one tell the system to use mykey instead of the id_rsa?
Com o sinalizador -i
.
FTFM:
-i identity_file
Selects a file from which the identity (private key) for RSA or
DSA authentication is read. The default is ~/.ssh/identity for
protocol version 1, and ~/.ssh/id_rsa and ~/.ssh/id_dsa for pro-
tocol version 2. Identity files may also be specified on a per-
host basis in the configuration file. It is possible to have
multiple -i options (and multiple identities specified in config-
uration files).
Então, então:
ssh -i mykey [email protected]