If you don't want to use a perl module you can try Inline::Python and use a Python module instead. Or just write the whole thing in Python since Inline::Python is a module.

Or if you want to do this seriously, your three best options are, use a CPAN module, open the source code of a CPAN module and work from there, or don't use perl at all and use OpenSSH. If you choose any of the first two options, you'll probably end up using a Core module at the very least.

Now if this is not the answer you expected, you are going to have to give more information on what you are trying to do, and why you have such an impractical restriction as "without using any perl module".