One of the things that most drives me crazy about Ciscos is the default setting that makes when you’re at a Cisco IOS “exec” prompt that if you type something that isn’t a command, it interprets it as an attempt to “telnet” to a host. This is a real pain in the backside as all typos become unwanted telnet attempts. It’s just a dumb default really.
Fortunately the fix is simple. Just go into the VTY settings and add a “transport preferred none”, eg:
line vty 0 4
transport preferred none
and that P.I.A. is fixed.