how to access machine using telnet

[Craig Hagerman]

On 8/31/06, Felipe Alfaro Solana <felipe.alfaro at gmail.com> wrote:
> > Can anyone tell me how to setup my Ubuntu machine so that I can telnet
> > into it and control it using a remote terminal?
>
> No ;-)
>
> Telnet is dangerous. So, we recommend you to go with SSH:
>
> sudo apt-get install sshd
>


I think it is kind of funny the way everyone predictably pops up with
a reflex reaction giving warnings about telnet and redirecting the
poster to ssh every time any topic on telnet comes up (on any mailing
list). Run away! run away! Telnet is dangerous!

A couple years ago I asked (maybe this list - I don't remember) how to
get telnet set up, and explained that I already used ssh and had a
good reason for setting up telnet. As I recall I had a dozen responses
telling me to install ssh -  ignoring the fact that ssh was already
set up and in use, and that I was well aware of the 'dangers' of
telnet already.

For anyone who is unaware of why telnet is considered insecure:

"Accessing a shell account through telnet method though poses a danger
in that everything that you send or receive over that telnet session
is visible in plain text on your local network, and the local network
of the machine you are connecting to. So anyone who can "sniff" the
connection inbetween can see your username, password, email that you
read and commands that you run."
(found at http://www.suso.org/docs/shell/ssh.sdf)

In my case (some time ago) I was dealing with a headless server I was
set up on the other side of the world. (I live in Japan - server was
in Canada) I wanted telnetd to be running, but not used except as a
backup way to get in if sshd failed to work. (Which had happened once
after changing the config file.) The insecurity of telnet is that
everything is sent in the clear and passwords could be 'sniffed' on
the local network. As a backup service there would be nothing to sniff
unless I couldn't get in via ssh.

</rant>

Anyway, I DO agree that ssh is preferable over telnet. However, if you
understand and accept the risks and have some need for telnet I assume
you would do install it with something like the following:

$ sudo apt-get install telnetd

Restart inetd service:
$ sudo /etc/init.d/inetd restart