OpenSSH/Configure OpenSSH to allow Public-key authentication
< OpenSSH
Create file touch ~/.ssh/authorized_keys and add public key of client to provide access.
Limit connecting host and command: It is also possible also to lock access to only be able to run a specific command, or use it only from a specific host [1]. See man ssh.
Example syntax::cat ~/.ssh/authorized_keys
from="10.22.33.45",command="/path/to/executable argument" ssh-rsa key name