Linux and telnet
Linux leaves the telnet door open? I've been running Linux for years. I can't speak for all installs, but since at least Debian 3.1, telnet isn't even running on the server unless you specifically install it. In fact, I believe on Ubuntu you don't even have SSH server installed unless you tell it to. There's been an effort on the part of Debian and Ubuntu, and probably many others, to move people away from telnet and to ssh. Apparently, many people are not aware that anyone running a network sniffer on the same network where someone is using telnet can watch the password go across in the clear. That's just the way telnet was designed.
Unfortunately, Windows machines come with telnet installed but not ssh, so people will sometimes enable telnet on the Linux servers. Better practice by far is to install Putty or some other SSH program for anyone who actually needs to access the server, and leave telnet off.
