my %args = ( host     => "localhost",
	     user     => "user",
	     port     => "22",
	     # psw    => "psw",
	     more => [qw(-o PreferredAuthentications=publickey)],
	     key_path => "/home/user/.ssh/id_rsa" );

my $sftp = Net::SFTP::Foreign->new(%args);
$sftp->die_on_error("Unable to establish SFTP connection");