KnownHostsFileCallback returns a HostKeyCallback that uses a known hosts file to verify host keys.

StaticKeyCallback returns a HostKeyCallback that checks the host key against a given host key.

DefaultKnownHostsPath is the default path to the known_hosts file - make sure to homedir-expand it.

ErrCheckHostKey is returned when the callback could not be created.

ErrHostKeyMismatch is returned when the host key does not match the host key or a key in known_hosts file.

nolint:gosec.

KnownHostsPathFromEnv returns the path to a known_hosts file from the environment variable SSH_KNOWN_HOSTS.