"CTRL+[" is a function of the standard telnet client, not of the protocol. Your Net::Telnet session will be closed for you when you call $telnet->close() or your $telnet object ceases to exist (i.e., if it is defined with "my" within a block, the connection will be closed at the end of the block).
Yours, "As soon as we started programming, we found to our surprise that it wasn't as
easy to get programs right as we had thought. Debugging had to be discovered.
I can remember the exact instant when I realized that a large part of my life
from then on was going to be spent in finding mistakes in my own programs."
--Maurice Wilk