Hey


Before writing perl program to access unix system first try
to see you can access unix machine using ssh from your command
$ prompt..if you were able to access it then
you shouldn't have any issues using Net::SSH.
DSA or RSA keys is something like public and private keys
If I am correct you will supply one key to connect to
unix machine and that machine will verify the key you supplied
and if its correct then you will be given access to the system
its password less authentication

Before digging into Net::SSH check to see you are able to access manually

Sridhar