The default identity filenames used by Net::SSH::Perl for passphrase-less SSH logins does not include the default RSAv2 identity filename (ie: id_rsa). To check if you are using RSA v2, you should have a .ssh/id_rsa file sitting in your home directory, in which case the Net::SSH::Perl object should be instantiated like this:

Note the identity_files option. Also, just change the path in case you changed the default identity filename when you generated the SSH keys.