Exploring Telnet: Frequently Asked Questions (FAQ)

Credit for this page goes to telnet.org

What is telnet?

Telnet is a network protocol and the application that uses the protocol. Most often, telnet is used to connect to remote computers and issue commands.

What is telnet used for?

Telnet is used for many reasons, almost all involve telneting to a remote computer and issue commands. Here are some examples: 

• Telnet to a server running BBS software and use various features
• Telnet to a server running a MUD and play games
• Telnet to a server and run a command line application such as pine to check mail
• Telnet to a Linux server and issue various Linux commands
• Telnet to a router and issue configuration commands (commands for Cisco IOS, Junos, etc)
• Telnet to an HTTP server port and issue test HTTP commands

Can I telnet to any computer?

No, only to computers running the Telnet server application, called a service or a daemon. This service allows for telnet clients to connect to them and issue commands.

Where can I telnet?

See the list provided by telnet.org: Places to Telnet

How can I telnet to my friend's computer?

You need to find and install a telnet on your friend's computer and your own. Additionally, all firewalls between the two computers must allow access to telnet.

Is telnet secure?

No, it is not encrypted and thus susceptible to packet sniffing. In most remote access situations, telnet has been replaced by ssh for improved security across untrusted networks.

How can I install a telnet client?

Check out telnet.org's page about Telnet Applications.

How can I install a telnet server on a Windows machine?

You might not want to as there risk, but if you insist:

Microsoft makes this knowledge base document available for installing and enabling the telnet service on Windows. It covers a variety of Windows versions: http://technet.microsoft.com/en-us/library/cc770501(v=ws.10).aspx

For a list of telnet commands for Windows 7, click here.

How can I install a telnet server on a Linux machine?

Same warning as before, but if you insist:

Most Unix like operating systems make a telnet server/daemon available. Check the man pages and your operating system documentation for more details. Below are a couple of examples for installing telnetd:

• Ubuntu: [root@host ~]$ apt-get install telnetd
• CentOS / Redhat / Fedora: [root@host ~]$ yum install telnetd

How can I use telnet to test a web or mail server?

You need to telnet to the appropriate ip and port, and know how to issue commands for the relevant protocol such as HTTP or SMTP.

As an example, you can use telnet to request a web page from a remote server with just a couple of commands:

• $ telnet example.com 80
• GET /path/to/page.htm

Here's an example provided by telnet.org for telneting to google.com and requesting the index page:

[rain ~]$telnet google.com 80
                        Trying 74.125.225.224...
                        Connected to google.com.
                        Escape character is '^]'.
                        GET /
                        HTTP/1.0 200 OK
                        Date: Mon, 30 Sep 2013 02:21:47 GMT
                        Expires: -1
                        Cache-Control: private, max-age=0
                        Content-Type: text/html; charset=ISO-8859-1
                        
                        --snip-remaining-output--
                        
                        Connection closed by foreign host.

Source:

This article is a rewire of https://www.telnet.org/htm/faq.htm We did not create the content and do not take credit for it. 

What are some other telnet reference sources?

You can find more good information on telnet at wikipedia.

Microsoft also has a Windows-oriented telnet faq @ https://www.lifewire.com/what-is-telnet-2626026.