You got a number of useful responses to this question when you posted it earlier. What is it you are still confused about?

Update: from perldoc Net::SSH:

FREQUENTLY ASKED QUESTIONS
       Q: How do you supply a password to connect with ssh      
          within a perl script using the Net::SSH module?

       A: You don't.  Use RSA or DSA keys.  See the
          ssh-keygen(1) manpage.
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Brad