How to configure a Telnet Server with Windows Server 2008

by [Published on 29 May 2008 / Last Updated on 29 May 2008]

The ability to telnet to and from your Windows 2008 Server is an important network feature that you can learn to configure in this article.

While the telnet client and server application has been around, well, forever, it is still very useful and, if you are like me, you may use it every day for a variety of network configuration tasks. In Windows Server 2008, configuring your server to respond to telnet requests and even using a Windows 2008 Server to telnet to another system with a telnet server can be quite different. Now, let’s find out how to configure both!

Why would I want to configure my Windows 2008 Server as a Telnet Server?

There are a number of reasons to configure a Windows 2008 Server as a Telnet server. Here is my list of them:

  • To perform remote CLI commands on your Windows 2008 Server, over a LAN or a WAN.
  • To be able to configure and troubleshoot all your network devices – whether they are Cisco routers, Linux servers, or Windows 2008 Servers, from a quick and simple command line – that is the telnet application.
  • To test connectivity to and from the server using a simple & reliable protocol

Let’s talk about an example. Say that I want to check on the status of some files that are supposed to be transmitted to my IIS server. There are a few quick commands that I can do to check on those files and I could do those commands much quicker than other alternatives if I could just get to a Windows command prompt. For example, instead of connecting to the server with Remote Desktop (RDP), with VNC, or another remote control method, why not just telnet to the server and quickly run the 2 commands that you need to run?

Of course, this is just a simple example but I am sure that there are many examples in your own organization where your administrative task could get done quicker if you could just telnet to the Windows server and perform the CLI commands that you need to perform.

How do you install the Windows Server 2008 Telnet Server?

To install the Windows 2008 Server Telnet server, you need to add a new Windows Feature. To do this open up Server Manager and click on the Features section on the left. Next, click on Add Features on the right, like this:


Figure 1

On the Select Features window, scroll down to the Telnet Server option and click its checkbox to select it. Now, click Next, then Install.


Figure 2

This begins the installation of the Telnet Server. After a few minutes, you will get a message that the installation is complete. That’s it - the installation is really “that” simple!

For more information on the difference between roles & features see my Admin tip: What is the difference between a Role and a Feature when customizing your Windows 2008 Server?

How do you install the Windows Server 2008 Telnet Client?

While, at this point, you could test your new Telnet Server from any computer that has the telnet application (like Windows XP or 2003) however, let’s use a Windows 2008 Server with the telnet client to connect to your Windows 2008 Server that we just installed the Telnet server on.

So, unlike in most previous Windows operating systems, we need to install the telnet client in Windows 2008 Server. To do this, we need to go into the same Server Manager application, to Features, then to Add Feature.

This time, we will choose to install the Telnet Client, as you see in Figure 3:


Figure 3

After clicking Next, then Install, my telnet client was installed very quickly, as you see in Figure 4, below.


Figure 4

Also, see my Admin Tip entitled Why is there no CLI Telnet in Windows Server 2008?

Enabling and Allowing Access to the Telnet Server

Before you connect to the new telnet server, hold on. Unlike many other features, just because the telnet server feature is installed, doesn’t mean that it is working. To actually use the telnet server, you need to, minimally, 1) start the service and 2) allow access.

To start the service, go into the Services MMC either through the Start menu or by running services.msc. Change the telnet service to start automatically and then go ahead and Start the service.

When you are done, it should look like it does in Figure 5:


Figure 5

By the way, you can also start and stop your telnet server from a command prompt by using net start telnet and net stop telnet.

At this point, you can telnet to your server and get a login prompt. You can login as administrator but no other non-administrative users can login. To allow other users to login, we need to configure who is authorized to login via telnet. To do this, you need to add the non-administrative user to the Local Group called TelnetClients. On my system, this group was already created for me however Microsoft’s official instructions say that it has to be created. So, if the group is not created on your system, go ahead and create the group.

Next, Add Users to this group. In my case, I added my already created user “ddavis” to the TelnetClients group, as you see in Figure 6, inside Computer Management.


Figure 6

Once the user was added, it was time to test the telnet server with a non-administrative user.

Testing your new Windows 2008 Telnet Server

To test our new Windows 2008 Telnet Server, I went over to another a Windows Vista that I had recently installed, across the LAN. Prior to using telnet on this machine, I had to install the telnet client feature which was similar to installing the telnet server feature in Windows 2008 Server.

To test our connection, I went to Start à Command Prompt. At the Windows command prompt, I telnetted to my new Telnet Server and was able to successfully connect, as a non-administrative user (notice the username I logged in with), as you can see below in Figure 7-10:


Figure 7


Figure 8


Figure 9


Figure 10

I think there are two important things of note that we can learn from Figures 7-10, above:

  1. Per the warning message above in Figure 6, Telnet is an insecure protocol. All traffic sent (including your username & password) are send in clear-text across the network. That means that your username & password could be seen by someone who is decoding packets on your network. This is a security risk even on a secure internal LAN.
  2. However, per the note in Figure 9, Windows Telnet supports NTLM authentication. You can force the telnet server to only allow NTLM authentication and this would make your telnet server much more secure.

Additionally, if you read the official Microsoft telnet operations guide below, you can learn how to customize the configuration for telnet and do things such as change the port number used, idle time, max # of simultaneous users, and more.

To see who is connected to your telnet server, you can use the following command:

tlntadmn -s

You can see an example of it in action in Figure 11.


Figure 11

Also, you can do other functions with the tlntadmn command like send messages to users (below, in Figure 12 & 13) and disconnect users.


Figure 12


Figure 13

For Microsoft’s official documentation on Telnet, you can take a look at:

Summary

There are a lot of benefits to adding a Telnet Server to your Windows Server 2008 system. We learned that there is more to using the telnet server than just installing the feature. The telnet server has to be started and user authentication has to be configured before the telnet server can be used. The telnet server can be used for many different types of command line administration, monitoring, and troubleshooting of your Windows 2008 Server. I hope you will give it a try!

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