use Net::SSH::Perl;
my $server='localhost';
my %params = (
            "protocol"         => '2',
            "use_pty"          => 0,
            "options"          => ["stricthostkeychecking no"],
            "identity_files"   => ["client_key"],
            "debug"            => 1,
        );

$ssh = Net::SSH::Perl->new($server, %params);
$ssh->login();