two
Port 23
n + 1
Students and professors will be able to Telnet to the server but unable to FTP files to and from the server.
Windows Vista does not provide a Telnet server. The instructions on how to change the port the server runs on will vary by software package. Without knowing what package you are using to provide Telnet, we can't provide instructions on how to configure it.
It has either a single client requesting a service
Pinging a server just checks that Particular system is present on the network. Telnet or SSH are application to login the server from remote and use the services provided by the server. In TELNET DATA is not encrypted so it's easy to hack. In SSH DATA is encrypted so it's safe.
Telnet offers no encryption, everything sent is in clear text including passwords.
TELNET Application layer services like Network Virtual Terminal are used to realise this. TELNET is the protocol used. Refer - Data Communication and Networking by Forouzan
The inherent problem in answering this question is that Windows XP does not have a Telnet server included, so there would typically be no purpose in even attempting it. You would need to install a third-party Telnet server (of which there are several) on Windows XP first. After the Telnet server is running, just open a command prompt in Windows Vista and enter:telnet substituting, of course, the correct IP address and leaving out the brackets.
Port 23 is the traditional port used for Telnet. Telnet is basically a protocol to allow a user to connect to another computer or server in order to view information or log in. When this port is open, it is often an indication that a malicious piece of software has planted a backdoor in your computer to allow other users to access it without your permission.
client/server application
Students and professors will be unable to Telnet to the server or FTP files to or from the server