Thanks i have tried the cipher => 'blowfish-cbc' thing and the encryption changed to blowfish but the program still aborts...
i still cannot control the login process and (apperantly) the Net::SFTP forces my program to exit... i cannot control it not even using eval{...}
The only way i made the dam thing work and login was to increase (a lot) the sshd (/etc/ssh/sshd_config) autentication timeout value..., but this is not a solution i cannot expect every user out there to change this value.
I think that i have all the necessary modules installed i have installed Net::SFTP from cpan (perl -CPAN... etc).