Function: Contains the public part of the host key. This file is writable
by the system account only and readable by world.
Creation: Together with the private part of the host key during SSH
server configuration (if requested). The new key can be created any time
by a system manager running the key generation utility, SSH_KEYGEN, which
creates both keys).
Use: Server host identification. Required on the SSH client in the [username.SSH2.KNOWNHOSTS] directory in order to use
any authentication method. Also required on the server for host-based authentication.