Turning off Telnet and FTP

The easiest way to turn off telnet and ftp servers on a server is not to install them in the first place. [e.g. When you install Redhat Linux 7+ as a Workstation, these servers are not installed].

If you install an older version of Linux or a different flavor or must install a server, but still want the telnet server (telnetd) turned off:

Look at /etc/inetd.conf and find the line that starts with:

    telnet stream tcp .... (etc.)

and put a # as the first character on that line.  Be sure line wrap is off
if you're using pico (run with `pico -w`) or use emacs or vi, which don't
generally insert line wraps.  

You'll then have to restart the inetd super server.

   killall -HUP inetd

That'll turn the telnet server off.

Follow the same instructions to turn off the ftp server - ftpd.
If you want to see attempts to use telnet and/or ftp, you can use several active intrusion detection systems (http://www.cert.org/security-improvement/implementations/i042.07.html).
One example of this is a program called klaxon (ftp://ftp.cerias.purdue.edu/pub/tools/unix/logutils/klaxon/README.local)