Simply install telnet from a Terminal (Ctrl-Alt-T in Simple Mode) with:
sudo apt-get install telnet
Note: you need to add the Debian stable/main repository to your /etc/apt/sources.list file in order to get this package (if you haven't done so already). (There are risks to using the Debian repositories on an ongoing basis, so always firstly test such usage by adding '-s' to the apt-get command to simulate the changes that will be made to your system and confirm that one of your required libraries / apps will not be overwritten or removed). And read this wiki page on adding repositories.
To use telnet, simply type the name of the server you want to connect to:
telnet pentagon.gov or telnet 192.168.1.102
Another way to connect to another machine is with the client PuTTY which supports multiple protocols (telnet, ssh, rsh). Luckily it is available with apt-get from a Debian repository.
Here's how to install it:
"sudo apt-get install putty"
If you are using Advanced mode, the program is found in Launch Menu > Applications > Internet > PuTTY SSH Client. If you are using Easy mode, open a Terminal window and type 'putty &'.
To telnet into your Eee PC, you will need to install the telnetd server, and use the inetd server.
Note: telnet access is inherently insecure, so it's not advisable to run a telnet server on your Eee PC if it is connected directly to the internet for any period of time. In that case, you should use an SSH server (contained in the Debian openssh-server package).
If there is no file /etc/fastservices, create that file with content:
openbsd-inetd
If the file already exists add the above line to the file.
The inetd service should already exist on your Eee PC. To check for its presence, use:
sudo which inetd
You should see:
/usr/sbin/inetd
You will likely not already have the telnet server on your Eee PC. To check for its presence, use:
sudo which in.telnetd
You should see:
/usr/sbin/in.telnetd
If you don't see anything, then you'll have to installd the telnetd server (again, from the Debian repository) using
sudo apt-get install telnetd
You can reboot and the service will start automatically. If you're impatient, you can just start the inetd service manually:
sudo inetd
Note that the telnet server is started by the inetd server [clarification requested]; you don't start the telnetd server directly. So if you jumped ahead and started the inetd server before installing the telnetd server, you can kill it off (and then restart it) by:
sudo killall inetd
Now you can telnet into your Eee PC, e.g. from a Windows PC using Putty or by typing in a command window:
telnet <eeePC ip address>
Use username 'user' and your normal login password. Same username and password if you ssh in instead.
To determine which IP address to use, open a Terminal window (Ctrl-Alt-T in Easy Mode) and type
ip addr
If you are on a wired network, you'll see the IP address listed under the eth0 interface.
When logging in (assuming a standard Xandros install), you need to use user as username. For password you need to enter the password that you specified when you configured your eeePC.