Using Assoc and FType to Create a New Type

On page 74 of Windows Command-Line Administration Instant Reference, I describe how to add an Open command to an existing file type, txtfile. The txtfile type already appears in the registry, so adding a new command to it is relatively straightforward. However, what happens if you want to create an entirely new type—one that doesn’t currently exist in the Registry?

Before you can do anything, you need to open an Administrator command prompt because Vista, Windows 7, and anything else newer won’t let you make the required registry changes with a standard account. Follow these steps in order to open an administrator command prompt.


  1. Choose Start > All Programs > Accessories.
  2. Right click the Command Prompt icon and choose Run As Administrator from the context menu. You’ll see a User Account Control dialog box.
  3. Click Yes. You’ll see a new command prompt open. However, instead of the usual title bar entry, you’ll see Administrator: Command Prompt. In addition, instead of opening to your personal user folder, the prompt will display C:\Windows\system32>. If you don’t see these differences, then you haven’t opened an administrator command prompt.

Let’s say you want to include a new file extension and it’s associated type. For example, you might want to create a .RIN file extension and associate it with a type of RINFile. Once you create this association, you may want to use Notepad to open the file. In order to perform this task, you need to use two different utilities as shown in the following steps.


  1. Type Assoc .RIN=RINFile and press Enter. You’ll see, “.RIN=RINFile” appear at the command line. This command creates a .RIN file extension entry in the Registry as shown here.
  2. Type FType RINFile=%SystemRoot%\Notepad.exe %1 and press Enter. Notice that you don’t enclose the command in double quotesit will fail if you do. You’ll see, “RINFile=C:\Windows\Notepad.exe %1” (or something similar) appear at the command line. This command creates the RINFile association in the Registry as shown here.
  3. Create a new .RIN file on your hard drive. You don’t have to do anything with it, just create the file.
  4. Double click the new .RIN file. Windows will open the file using Notepad.

This technique works with any file extension and association you want to create. In fact, you could easily create a batch file to patch user configurations where the file associations have become damaged in some way. The big thing to remember is that this is always a two-step process when the file extension doesn’t already exist or the association is new. Use the Assoc utility to create a link between any file extension and it’s association and the FType utility to create the association itself. Let me know if you have any questions about this technique at [email protected].


New RecImg Utility in Windows 8

Microsoft is constantly changing the command line, which is why books such as Windows Command-Line Administration Instant Reference get outdated. Every new version of Windows comes with new command line utilities. In most cases, these new utilities support new Windows features or allow some new level of maintenance or administration. The RecImg utility creates an image of the Windows 8 installation, including installed applications, to the location you specify. The purpose of this image is to allow a refresh of the Windows installation should something happen to it. A refresh installs a new copy of Windows, but preserves the data and application setup. In many respects, this feature sounds like a simplified version of products such as Norton Ghost. You can read about this new refresh functionality in the Refresh and reset your PC post on the Building Windows 8 site.

I find this new feature exciting because it provides the means for someone like me to recover a hard drive even if I have to support several configurations for a book. It should be possible to create as many images as needed and know that Windows will support them because the feature is built into the operating system. The basic command line for working with this utility is:

RecImg -CreateImage Location

where Location is the directory you want to use for the Windows image. As with any Windows 8 feature, the current version of the utility has problems that you can read about on the Computer Performance site. I’m assuming at this point that the utility will include additional command line switches. Otherwise, Microsoft wouldn’t have included a specific -CreateImage command line switch. Of course, the presence of this new utility means that administrators can perform image updates from a batch file or as part of automated maintenance.

I’ll keep you posted on this, and other, Windows 8 utilities as I have time to review and study them. In the meantime, let me know if you hear anything about interesting new Windows 8 utilities and utility changes. Also let me know if you hear about any utilities that Microsoft decides not to support. Often, you find out about these changes only after you’ve tried to use it in a batch file.

What is your take on this new Windows 8 feature? Let me know at [email protected].


Windows 7 and the PowerCfg Utility

On page 327 of Administering Windows Server 2008 Server Core, you find the PowerCfg utility and may not even find it all that interesting. Yes, this utility makes it possible to configure the power settings for a system from a remote location. An administrator can use it to ensure that everyone has a power saving setup by adding the command to the user’s login script. However, as utilities go, it isn’t all that interesting. For that reason, the command doesn’t even appear in Windows Command-Line Administration Instant Reference. A number of beta readers said they didn’t even use it.

Microsoft is showing an increasing interest in power management with each version of Windows. In fact, from what I’ve been reading about Windows 8, power management is going to take a relatively large leap forward (read about the changes in, “Building a power-smart general-purpose Windows“). With this in mind, the Windows 7 version of the PowerCfg utility has added four new command line switches:


  • /Requests: Enumerates the application and driver power requests. Applications and drivers make power requests to ensure that resources are available when needed. However, sometimes these requests can also become a problem when they’re abused. Power requests can also prevent the computer from automatically turning the display off or going into hibernate mode, which wastes power.
  • /RequestOverride: Forces the system to disregard an application or driver power request. The positive aspect of this command line switch is that you can enforce a power management strategy when you have applications and drivers that abuse power requests. However, by denying applications and drivers access to resources, you could also cause system instability or data loss when the application or driver crashes.
  • /Energy: Performs an energy survey of the system. This is probably the most important addition that Microsoft has made. Using this particular feature, you can detect system elements that are consuming a lot of power and reduce its energy footprint. Generally, you use this feature with just the system running to determine what the system uses. However, you can also use it with single applications open to detect the energy cost of using that application, which I think is actually the more revealing way to use this command line switch. Most people don’t associate an energy cost with using an application. This feature makes the energy cost significantly more apparent. Yes, every application you use has a cost, so keeping needless applications open is costing you money.
  • /WakeTimers: Displays a list of timers that are set to wake the system from sleep or hibernate states. Waking a system too often also costs you money. For example, it costs more to perform individual maintenance tasks at separate times than to perform them during a single time. An organization could use this command line switch to ensure that every system wakes at the same time, performs required maintenance, and then goes back into either the sleep or hibernate states.

As mentioned in the list, I consider the /Energy command line switch the most important PowerCfg addition to date. If you’re interested in self-sufficiency, as I am, then you begin to count even the pennies of energy usage. For example, in my CFLs for Free I discuss how I bought just one CFL and turned it into a complete setup for my entire home. This particular feature has allowed me to perform an energy survey of the applications I use. I found out, for example, that streaming audio using Firefox does indeed cost less than using a separate device for the purpose (such as a radio) and also delivers clearer audio. However, streaming impacts system performance and tacks a network bandwidth penalty onto other applications that rely on Internet connectivity, so there are times where using the separate device is actually better.

Let’s look at the /Energy command line switch in a little more detail. The easiest way to use this command is to open an Administrator command prompt, change directories to a directory you can write in (I’m using C:\Temp), and then type PowerCfg /Energy and press Enter. I purposely ran the command with a number of applications running and some misconfiguration in place to generate some errors, warnings, and informational messages as shown here.


The report required a little over a minute to generate. You can see the results in the Energy-Report.HTML file. Here are the results I generated from this run.


The PowerCfg utility makes it possible to diagnose energy problems with a system and significantly reduce the cost of running it. The language of the report does require a little interpretation at times, but normally the language is plain enough for an administrator to figure out with little effort. By correcting every error and 12 out of the 13 warnings, I was able to reduce the power requirements of this system by about 15 percent (as measured by a watt meter). So, how does that equate in dollars? You use the equation: Cost = ((Watts / 1000) * Hours Used) * kWh rate, where kWh is the kilowatt hour rate provided by your power company on your electrical bill. This system was averaging a little over 520 watts before tuning it. For the sake of argument, let’s say you’re using it 60 hours per week and the electrical rate is $0.12. The weekly cost of running this system is:


((520 / 1000) * 60) * 0.12 or $3.74

After tuning this one system the power usage was only 442 watts on average. That means the weekly cost went down to:


((442 / 1000) * 60) * 0.12 or $3.18

a savings of $0.56 for this one system each week or a total of $29.12 for the year.  I have three systems that I tuned this way, so I’m hoping for a $87.36 savings from performing this tuning. Each system required about 30 minutes to tune, so I’ve made $58.24/hour from this activity. If you’ve read other posts, I do like to put a dollar figure on my time—you should too. Not many people can afford to throw away money like this and the PowerCfg utility, along with a watt meter, can help you better understand how your system uses (and abuses) power.

There are two additional command line switches you should know about when using the /Energy command line switch. The /Duration:Time command line switch changes the duration from 60 seconds to some other value. For example, if you want to change the duration to 120 minutes, you’d type /Duration:120. Longer testing times are often required when you’re trying to determine how an application is using energy. Take my advice and don’t set the duration lower than the default 60 secondsyou’ll be disappointed with the results.

The /XML command line switch outputs the data in XML format so that you can incorporate the information into a database. If you have a large setup, the XML format is absolutely essential. No one has time to look at individual HTML pages. Using XML output and a centralized database also makes it possible for you to look for organization-wide trends, which could produce even bigger savings.

The /Energy command line switch can also be used with the /Trace command line switch to trace energy usage without performing any analysis. This output isn’t as helpful or as accessible as using the /Energy command line switch alone. The output is an Event Trace Log (.ETL) file. To view this file, open the Event Viewer console found in the Administrative Tools folder of the Control Panel. Right click the Event Viewer folder and choose Open Saved Log from the context menu. You’ll see a dialog box asking whether you want to convert the .ETL file into the new format used by Windows 7. Click Yes. You’ll see a list of energy events like the ones shown here.


By carefully reviewing the events, you can discern energy usage patterns, filter data about specific events, and perform other analysis. However, this raw data is a little hard to use and the administrator would be better off generating the report, unless your organization has an application designed to analyze the raw data in some way.

So, how do you save energy in your organization? Do you rely on specialized tools such as a watt meter and PowerCfg? If not, how do you tune your equipment to deliver optimum service and minimum cost? Let me know at [email protected]


Obtaining Command Line Help

Both Administering Windows Server 2008 Server Core and it’s more diminutive counterpart, Windows Command-Line Administration Instant Reference, are reference manuals that tell how to use the command line to perform specific tasks. The first book is more complete, in that it contains many uncommon commands and utilities. The second book is designed to provide more hands-on help by supplying a significant number of actual usage examples. In both cases, you get a significant amount of help about the commands. As long as you have one of these two books by your side, you’re in great shape for knowing how to use the commands at the command line. Unfortunately, the reality is that most of us don’t stuff a library full of books in our back pocket. Even with an e-Reader, such as the Kindle, you can be sure of having the device available every time you need it. So, how do you get at least some quick help when there aren’t any resources available?

The first thing to remember is that you can get at least some useful information for any command or utility by using the /? or -? command line switches (some commands and utilities are peculiar in that they require either the /? or the -? command line switch, while many will allow you to use either). For example, when you want to discover how to use the Dir command, you type Dir /? and press Enter. Here’s typical output when using the /? command line switch.


This help screen is also typical in showing what you get. Help normally includes a short description of the command, the command line syntax, and a short description of each of the command line switches. You may also see usage examples for more complex commands. In rare cases, the help screen will provide an URL for additional help.

Some commands and utilities are complex enough that they require several help screens. For example, if you type WMIC /? and press Enter, you’ll see a list of help topics, not help of the sort provided for the Dir command. Let’s say you want to know more about the CPU topic. So, now you type WMIC CPU /? and press Enter. The help looks a little more normal now, but still isn’t very complete because you need to choose a subcommand. Perhaps you want just a list of CPUs on a system, so you request information about the List subcommand by typing WMIC CPU List /? and pressing Enter. Wow, now you see a number of listing formats. This time you add a listing format by typing WMIC CPU List Brief /? and pressing Enter. It turns out that you can also discover information about command line switches used with the Brief format. The final level in this case is to type WMIC CPU List Brief /Translate /? and press Enter. The WMIC utility is unique in providing so many levels of help, but other complex commands and utilities, such as Net, do provide multilevel help.

No matter how many help screens you see, sometimes it isn’t enough to give you the help you need. That’s when you need to find your copy of my book to get additional information. Of course, a single book can do only so much—some complex commands and utilities may require still more information. Technet is a good place to start. For example, you can find an excellent article on WMIC at Knowledge base articles also provide useful information, especially when it comes to issues that Microsoft has solved for a given command or utility. For example, the Knowledge Base contains an article entitled, “How to find computer serial number” that relies on WMIC. Finally, make sure you look at third party articles, such as the one entitled, “WMIC: the best command line tool you’ve never used.”

Many people complain about not being able to remember all of the commands and utilities, and this is a problem. After you use a command or utility often enough, you tend to remember it, but the memorization process can take time. Unfortunately, there isn’t any single quick method of finding every command or utility on a system. However, you should start by typing Help | More and pressing Enter. (Using the More command lets you see the information that a utility has to provide one screen at a time, rather than seeing the information scroll right past.) You’ll get a list of common commands like this one.


Not all of the commands appear on this list and none of the utilities do. Another way to obtain the information you need is to type Dir *.COM and press Enter in the \Windows\system32 directory. (You can type CD \Windows\System32 and press Enter to get to the appropriate directory.) Every directory entry you see is very likely a utility. However, many utilities are in .EXE form, so you also need to type Dir *.EXE | More and press Enter. You can eliminate files that contain more than eight letters in the filename from the list in most cases because command line utilities usually rely on the old 8.3 naming convention. Check filenames that look like they could be what you want by typing Filename /? and pressing Enter (where Filename is the name of the file you want to test). Useful command line utilities will generally display a help screen.

Now that you have a better idea of how to get command line help when you need it and where to obtain a list of useful commands and utilities, you should take some time to try it out for yourself. What techniques do you use to obtain the additional information you need at the command line? Let me know at [email protected].


Automating Your Configuration with a Daily Batch

Batch files are still an important part of your system, especially if you find that you need to perform certain configuration tasks every day. Both Administering Windows Server 2008 Server Core and Windows Command-Line Administration Instant Reference discuss batch files, but this post is about a practical example of a batch file in daily use.

My system has a daily batch file. It runs every morning when I start the system up. (To save electricity, I do turn off my system every night and find that things also run better because I do.) The main reason for using a daily batch file is to configure my system so I don’t end up performing the same repetitive tasks every day. I tell the computer what to do and it performs the required configuration for me. After I get my cup of coffee, my system is ready to go—fully configured for my use.

The daily batch file appears as an entry in the Startup folder on my system. Placing the file in the Startup folder means that it runs automatically, but that I can also easily disable the batch file should I wish to do so. Use these instructions to add a daily batch file to your Startup folder:


  1. Choose Start > All Programs. You see a list of entries including Startup.
  2. Right click Startup and choose Open from the context menu. (Unless you want everyone to use the same automatic batch file, you don’t want to choose Open All Users.) You see a copy of Windows Explorer open for the Startup folder.
  3. Right click anywhere in the right Windows Explorer pane and choose New > Text Document from the context menu. Windows will create a new text document named New Text Document.txthowever, only the New Text Document part of the filename is highlighted.
  4. Highlight the entire filename and type Daily Tasks.bat. Make absolutely certain that you also overwrite the .txt part of the filenameDaily Tasks.bat.txt won’t do anything for you.
  5. Press Enter. You see a Rename dialog box that asks whether you’re sure that you want to change the extension of the file.
  6. Click Yes. Windows renames the file.

Of course, the file is empty at this point. Right click Daily Tasks.bat and choose Edit from the context menu. Windows will open a copy of Notepad with the empty batch file loaded. At this point, you can start typing commands for Windows to execute automatically when you start up in the morning. It’s possible to execute many commands directlyespecially those that are meant to execute at the command line, such as W32Tm /Resync, which forces an update of the system clock. Other commands require that you use the Start command to execute them. For example, you might want to tell Firefox to automatically open the Astronomy Picture of the Day site using this command:


Start “C:\Program Files\Mozilla Firefox\Firefox”

<font<> <font<>The Start command starts Firefox in this case. It passes the URL you provide to Firefox as a command line parameter. Obviously, the application must support command line parameters for this technique to work. More applications than you might think do support command line parameters (many undocumented), so a little research can provide a lot in automation.

Any command that you can execute in any other batch file is also available when you’re starting Windows. There is one special consideration. You’ll likely find that executing one command immediately after another causes timing problems when Windows is initially starting. For example, if you try to open several Web sites, you’ll find that Windows actually misses opening a few unless you provide some sort of wait period between commands. Fortunately, the Choice command fulfills this task perfectly. For example, the following command provides a 15 second delay that you can insert between commands:


@CHOICE /C:N /N /T:15 /D:N

Using this command the user won’t even be aware of the delay. The @ symbol makes the Choice command invisible. The /C command line switch provides the available choices (which consists solely of N in this case). The /N command line switch hides the list of choices from view. You create the actual timeout value using the /T command line switch, which is set for 15 seconds in this example. However, the /D command line switch actuates the delay by automatically choosing N after the 15 seconds. In short, this entire command line is a wait statement.

If you want your batch to run more or less invisibly, make sure you start it with an @Echo Off command. Otherwise, every command appears in the window. It’s helpful to check for errors when you first put the batch file together and when you make changes. Adding an @Pause at the end of the batch file keeps the command window visible so you can check for errors.

After you finish the batch file, you can execute it as you would any other batch file. The only difference in this situation is that this batch file executes automatically each day because it resides in the Startup folder. When you need to make changes to this file you can choose Start > All Programs > Startup, then right click Daily Tasks.bat, and choose Edit from the context menu. The file will open in Notepad for you.

This is one of the more interesting and useful ways to employ batch files. What are your favorite batch processing techniques? Let me know at [email protected].


Interacting with the Remote System Using Telnet

Today marks the last post in my Telnet series unless someone writes with additional ideas on issues they’d like me to cover. So far, I haven’t received any requests for Telnet scripting topics, so I’ve decided that perhaps there isn’t a lot of interest in this topic. I discussed basic Telnet connectivity in the Using Telnet to Perform Tasks post. The last post, entitled “Sniffing Telnet Using Wireshark,” covered Telnet security issues. Today’s topic is a natural extension of the topics discussed so farnow that you have an interactive session with a remote system (router, server, or workstation, it doesn’t matter), what can you do with it?

My book, Administering Windows Server 2008 Server Core,” provides a few ideas on the topic, but not very many. I’m thinking now that perhaps I should have discussed this topic in “Windows Command-Line Administration Instant Reference,” but then there is always the question of the cost to other topics and I had no idea when I wrote that book that Telnet was still so popular with some administrators. The short answer is that you have a fully functional command prompt.

The problem is that you’re working with a remote command prompt, not the local command prompt. So, the command prompt you’re accessing is the one on the remote system, with all its attendant resources and limitations. As a consequence, unless you’re working with that system every day, you’ll want to type Ver and press Enter to see which version of the command prompt you’re using. It seems like a simple thing to do, but some administrators don’t and later discover that problems at the command line had nothing to do with the session, but the version of the command line. If you’re working with Windows, you can find a complete list of Windows OS Version numbers on MSDN.

Knowing the version number and the associated operating system name lets you look for commands for that OS in either of my books or you can look them up online. For example, you can use the search phrase, “Windows XP Command Line” on Google (or any other search service) to obtain quick access to sites such as Technet where you can find a listing of associated commands from A to Z. Obviously, these sites will only tell you which commands are available, not how to use them, but knowing what’s available does help.

Another problem that many administrators encounter is that they don’t consider the environment. Again, the environment focuses on the remote system, not your local machine. So, that favorite path might not be part of the Path environment variable and typing a much beloved command won’t work at all. Consequently, it pays to type Set | More and press Enter so that you can look through the environment variables to ensure everything you need is available. This command also provides some essential cues about the remote system configuration. For example, if the Set command reveals a ProgramFiles(x86) environment variable, then you know you’re working with a 64-bit system and some older commands may not work as anticipated. Use the Set command to add or modify any environment variables required to get your work done.

At this point, you know which commands you can execute and you know that the environment is configured for use. What you don’t know is whether you have the rights required to accomplish the task. You can use commands such as ICACLS to verify your rights or you can simply try the command to see whether it completes successfully. The important thing to keep in mind is that newer versions of Windows employ the UAC, even at the command line, so you might find your efforts thwarted.

Even when everything is working properly and you have all of the required rights, you should avoid using certain commands in a remote session. For example, you definitely don’t want to start another copy of Telnet from the remote session (assuming the remote session will even allow it). Using the WinRS command probably won’t work well either. However, Terminal Server commands such as QWinSta appear to work just fine. Let me know your thoughts about Telnet at [email protected].


Sniffing Telnet Using Wireshark

In my previous post about Telnet entitled, “Using Telnet to Perform Tasks” you discovered how to use Telnet to work interactively. Now you have enough information to view some of the security issues with Telnet. It’s incredibly easy for someone to monitor your Telnet session. The only protection you have is firewalls and other security you might have in placeTelnet is completely open and offers nothing in the way of security. Lack of security is one of the reasons I didn’t cover this utility in the Windows Command-Line Administration Instant Reference.” (Telnet is covered from a command line perspective in Administering Windows Server 2008 Server Core.”) However, the lack of security isn’t a problem in some situations and many administrators prefer to use Telnet to manage some network hardware such as switches and routers. Consequently, the main emphasis of this post is building an awareness of the security issues behind using Telnet so that you can make a good decision about using it to meet your needs.

Before you can see the security issues for yourself, you need to download a utility to sniff packets on your network. This post will rely on a free utility named Wireshark because it does the job admirably and is supported on a number of platforms. Because I’m using the 64-bit version of Windows 7, I downloaded the 64-bit Windows installer for the 1.4.7 version of Wireshark. To make things simple, I performed a full install. Part of the Wireshark setup will also install WinPcap, so you don’t need to install this product separately. If you’re using some other version or configuration of Wireshark, your screen may not look precisely like mine.


Using a sniffer is somewhat dangerous and you need administrator privileges to do it. This post isn’t designed to make you an expert in protocol sniffing. In fact, this post is exceptionally simple and is designed only to make you aware of deficiencies in Telnet security. The nefarious individual who gains access to your network to sniff about will have significantly more skills and be able to learn considerably more than you’ll learn using the simple directions in this post.

After you complete the installation, you’ll be able to start Wireshark. Choose Start > All Programs > Wireshark and you’ll see the initial Wireshark display shown here.


Wireshark isn’t configured to work with Telnet at the outset, so you need to tell it what to sniff. Click Capture Options and you’ll see what looks like an incredibly complex Capture Options dialog box like the one shown here.


We’re not going to worry about the vast majority of these options. In fact, you only need to set two options to sniff out Telnet packets. Look first at the Interface field. Make sure it’s set to Local. Select your network adapter from the drop down list box. The network adapter will normally have a human readable name, not something odd as shown in the screenshot.

Next you need to tell Wireshark what to sniff on the interface you’ve selected. Click Capture Filter. Type Telnet in the Filter Name field and port 23 in the Filter String field. Click New. Your dialog box should look like the one shown here.


Click OK. You’ll see the filter criterion entered in the Capture Filter field. More importantly, Wireshark is now configured to offer a Telnet filter anytime you need one. Click Start. The Wireshark display will change, but you won’t see anything on itthe display will be blank.

Open a command prompt and start a copy of Telnet in interactive mode. Make sure you open a command prompt with administrator privileges. The act of starting Telnet won’t create any packets as you can see in Wireshark. In fact, type ? and press Enter. You’ll see that Telnet is still perfectly safeit isn’t generating any packets.

Use the Open command to open a connection to your server. Simply typing O ServerName and pressing Enter generates packets. You can see them in Wireshark like this:


Notice that some of these entries are labeled Telnet Data. In addition, the Source and Destination columns tell you which direction the information is flowing (the client is in this case). Click on the first of these entries and you’ll see that the middle panel contains some information about the Telnet Data. Open the Telnet entry and you’ll see some interesting information as shown in the figure. For example, the packet information tells the viewer that Telnet is set to use the authentication option.

Go back to the command prompt now. Type y and press Enter to send your password information to the server. Of course, one of the big questions you probably have is whether Telnet is exposing your username and password. Near the end of the packets, you’ll find one that contains an Suboption Begin: Authentication Option entry like the one shown here.


In this case, the option entry tells the server that the client won’t forward the authentication credentials. The option works because I’m already signed onto the server and the server already has my credentials. This is one of the items you’ll want to check for your own Telnet setup, however.

Unfortunately, this session isn’t safe by a long shot. Type just a single letter, a D, at the command prompt. You’ll find that typing this single letter generates a packet that you can see with Wireshark like the one shown here.


In fact, you’ll find that every action on your part creates more packetseach of which is easily sniffed by anyone with Wireshark or any other application of the sort. Finish the command by typing ir and pressing Enter. You’ll see the expected response at the command line.

At this point, you can also see the response from the server in Wireshark. The text isn’t as readable because it contains all of the control characters normally used to format the text. However, here’s an example of the response as it appears on my system.


Look at this response carefully and you’ll see that anyone can learn precisely what you’re doing. If you have to enter passwords to perform a particular task, the viewer will get them too. Telnet isn’t a secure method to manage anythingyou need to provide a secure environment in which Telnet can run. This post only touches on the tip of the iceberg, of course. Let me know if you have any questions about it at [email protected].


Using Telnet to Perform Tasks

The previous post in this series, Configuring Telnet, helped you get Telnet set up on a system. Now that you have Telnet installed, you can use all of the command line and interactive features described in Administering Windows Server 2008 Server Core to access it. For example, you can simply type Telnet <Name of Server> and press Enter to start a session with that server. Because of the way Telnet works and the commands that you’ll issue, it’s always a good idea to use an Administrator command line when working in either Vista or Windows 7. To open such a command line, you choose Start > All Programs > Accessories, right click the Command Prompt entry, and choose Run As Administrator from the context menu. You may have to supply a password to gain administrator access.

When you plan to work with Telnet for an extended period, you might find the interactive environment more suited to your needs. To enter the interactive terminal, you simply type Telnet and press Enter. This action places you at the Microsoft Telnet prompt, but doesn’t open a connection for you. Type ? and press Enter to see a list of available commands as shown here.


One of the advantages of using the interactive prompt is that you’ll find it easier to configure Telnet options. To see these options, type Set ? and press Enter. For example, if you want to make your Telnet session a little more secure (and the emphasis is on little), type Set NTLM and press Enter. Some settings are a toggle. For example, if you want to remove NTLM authentication, you type Unset NTLM and press Enter. Type Unset ? and press Enter to see a list of toggled settings. Here is a list of the settings available when using the Windows 7 version of Telnet (your version of Telnet might vary).


The ability to set or reset settings is nice, but it would also be nice to know how Telnet is configured. To obtain this information, you type D (for display) and press Enter. You’ll see a list of configured settings. The default settings depend on your version of Windows and how you configured Telnet in the past. If you don’t see a particular setting, it means that the setting either isn’t configured or is toggled off (unset).


Simply configuring a setting doesn’t guarantee that Telnet will use it. The server determines whether a particular setting is valid. For example, you can request NTLM authentication, but the authentication won’t occur if the server doesn’t support it. Likewise, your choice of terminal is sent to the server, but the server ultimately chooses the terminal type, which is going to be ANSI in most cases.


To create a connection in interactive mode, you type O <Name of Server> and press Enter. You may see a warning message about sending your password in the clear. Type Y and press Enter. At this point, you’ll see the standard Telnet prompt at the server. To regain access to the client side prompt, you press a control key combination. The default is Ctrl+]. This will take you back to the client Telnet prompt where you can enter additional commands. When you want to go back to the server side, simply press Enter twice.

To check your connection, type St and press Enter. You can also ask the server questions, such as “are you there” using the Sen command. To see all of the send options, type Sen ? and press Enter. The help list shows those commands that Telnet definitely supports. However, the Knowledge Base article entitled, “The TELNET Protocol” seems to tell a different story (I’ll check out these additional commands for a future post). For the sake of doing something interesting, try typing Sen AYT (for are you there) and press Enter. Here is typical output from this command.


Now that you’ve asked for information, press Enter twice to see the server’s response. In most cases, you’ll see YES as shown here.


You have several ways to close a connection. However, for this session, press Ctrl+] to return to the Telnet client session. Type C and press Enter. The connection is now closed. To verify this fact, type St and press Enter. Type Q and press Enter to leave the Telnet interactive environment. Now, here’s the interesting part of all this. You can also script this sort of behavior to make many tasks automatic. A future post will also pursue this topic in more detail. For now, let me know if you have any questions about the basic interactive session at [email protected].


Configuring Telnet

Readers have written in to tell me that they’d really like to see more about Telnet after reading my Telnet Not Included post. Of course, there was the usual disagreement as to where I should begin the discussion, so I decided to start at the beginning. As previously mentioned, I do cover this command in my book Administering Windows Server 2008 Server Core,” but don’t cover it in “Windows Command-Line Administration Instant Reference.”


Adding the Telnet Server feature to a server will likely require a restart. Consequently, you should only take this task on when you know that you can reboot the server afterward.

Neither books tells you how to configure Telnet, which is a necessary first step because Microsoft doesn’t install this application automatically any longer due to some serious security considerations. The purpose of this post then is to help you configure a Telnet setup that consists of a server (WinServer for the purpose of these posts) and a client (Main). You’ll need to substitute the names of your systems when working through the commands on your system.


It’s important to note that you can perform this task on a single machine by configuring both client and server.

WinServer is a Windows 2008 R2 Server. If you have some other version of Windows, the instructions I’m providing here might not work precisely.


  1. Choose Start > Control Panel. You’ll see the Control Panel window shown here.
  2. Click Turn Windows Features On or Off. You’ll see the Server Manager window.
  3. Choose the Features folder in the left pane. You’ll see a list of installed features like the ones shown here.
  4. Click Add Features. You’ll see the Add Features Wizard.
  5. Check the Telnet Server entry as shown here.
  6. Click Next. You’ll see a message about the server needing to be restarted after you complete the installation.
  7. Click Install. Windows installs the Telnet Server feature.
  8. At some point, you’ll see an Installation Succeeded message. Click Close to close the Add Features Wizard.
  9. If necessary, reboot your system (Windows will tell you when it’s necessary to reboot). Unfortunately, your Telnet installation isn’t active yet.
  10. Open the Services console found in the Administrative Tools folder of the Control Panel (depending on how your configure your server, you might actually find this folder right on the Start menumy recommended placement for such an important feature).
  11. Locate the Telnet entry. You’ll notice that the service is not only stopped, but it’s also disabled as shown here.
  12. Double click the Telnet entry. You see a Telnet Properties dialog box like the one shown here.
  13. Choose Automatic (Delayed Start) in the Startup Type field and click Apply. Using a delayed start seems to ensure fewer problems when working with Telnet.
  14. Click Start. Telnet should now be accessible on the system.

You can also configure the Telnet server from the command line. To set the server startup configuration type, SC Config TlntSvr Start= Delayed-Auto and press Enter. To start the server, type SC Start TlntSvr and press Enter.

Once you have Telnet installed on the server, you also need to install it on your workstation. The following steps get you started.


  1. Choose Start > Control Panel. You’ll see the Control Panel window.
  2. Click Programs. You’ll see the list of Programs options.
  3. Click Turn Windows Features On or Off. You’ll see the Windows Features dialog box.
  4. Check the Telnet Client option and click OK. Windows will install the Telnet Client.

Of course, you don’t know whether your setup will even work. So, it’s time to check your setup.


  1. Choose Start > All Programs > Accessories to display the Command Prompt link.
  2. Right click Command Prompt and choose Run As Administrator from the context menu. You’ll see a User Account Control dialog box where you click Yes. At this point, you’ll have an administrator level command prompt to use.
  3. Type Telnet WinServer (or whatever the name of your server is) and press Enter. You’ll see a message warning you about sending your password to the server. The password is sent in the clear and this is extremely dangerous from a security perspective.
  4. Type Y and press Enter. Telnet will create a command prompt session on the server for you.
  5. Type Echo %ComputerName% and press Enter. You’ll see that the name of the system matches your server, so you really do have a connection to it.
  6. Type Exit and press Enter. Telnet ends the session with the server.
  7. Type Echo %ComputerName% and press Enter. The output now corresponds to your local workstation.

At this point, you have a Telnet configuration to use for future posts. Of course, you can start experimenting with it now. Any command you can normally type at the command prompt, you can likely type at the Telnet prompt as well (as long as there are no graphics involved with executing the command). Now I need to know what sorts of topics you’d like me to cover. Send me e-mail at [email protected] with your requests.


Telnet Not Included

Every book I’ve written has required some hard decisions. Believe me, I think about every omission and addition at length, and then I think about them again. In many cases, I’ll ask my editors, especially my technical editor about it. In some cases, the beta readers for my book will get an e-mail about the topic as well. I made these sorts of decisions when writing Windows Command-Line Administration Instant Reference as well. So it was, after trying to wring everything I could out of every page in the book, I was faced with the unpleasant decision of having to leave Telnet out. It wasn’t an easy decision because I had included it in past tomes about the command line, such as “Administering Windows Server 2008 Server Core,” (see page 440 of that book) which also contains a wealth of other commands.

Readers have asked about the Telnet omission. I’ve been surprised to find that quite a number of people still use this utility and would have liked a more comprehensive discussion of it in my current book. There were a number of reasons for the omission. The most important at the time is that Telnet isn’t enabled by default anymore on Windows. You must install it as a separate item. In fact, you must also install the client on newer systems as shown here for Windows 7.


So, why is everyone apparently making it difficult to use Telnet? Well, it turns out that Telnet has been implicated in more than a few security problems. Telnet was designed for a time when you could trust a connection. It doesn’t provide modern security features, such as encryption for the username and passwordit passes this information in the clear so anyone can grab it. In fact, a simple check on Microsoft’s Knowledge Base shows 1,430 hits for Telnet Security Issues (as of this writing). There are many non-Microsoft sites, such as this James Stephens blog entry, that detail the problems with Telnet as well. With pages at a premium, I decided the security issues surrounding Telnet were a good reason not to include it.

I’ve written a number of command line reference books. Each with a different audience in mind. In Windows Command-Line Administration Instant Reference I chose to provide support for administrators who need quick reference to actual commands, rather than simply a command reference. In addition, the page count of this book is smaller and the book itself is a smaller size to make it easy to carry around. The addition of examples and the reduction in size meant that I had to choose which commands to cover quite carefully. As described in another recent post, Techniques for Choosing a Technical Book, it’s important that the reader choose the book that meets their needs. In some cases, readers will be better served by the more complete list of commands provided by Administering Windows Server 2008 Server Core, which is an actual reference book.

Of course, I’m always looking for ways to improve my books to make the next edition better suited to meet your needs. If I receive enough e-mail about Telnet, I may very well included it in the next edition of Windows Command-Line Administration Instant Reference. So please keep those e-mails coming! If you’d really like to see Telnet included in my next book, contact me about it at [email protected].

So, here’s the short story about Telnet. As with most command line utilities, you can obtain general help by typing Telnet /? and pressing Enter. You’ll see the help screen shown here:


Notice that I’m using an Administrator command prompt. You absolutely have to elevate privileges to use Telnet successfully in Windows 7. In addition, you’ll need to open a hole in your firewall for port 23 (unless the Telnet server you want to contact is at a different porta minimal, but helpful security precaution).

In order to connect to a server, you type Telnet <ServerName>, where ServerName is the name of the server you want to contact. For example, if you want to contact a server named WinServer, you type Telnet WinServer and press Enter. Once you enter Telnet, type ? and press Enter to get help for that session.

It’s important to note that Microsoft provides some Telnet-related commands that you should know about if you really need to use Telnet for administration tasks. For example, the Telnet Server is TlntSvr.exe and you can use the TlntAdmn utility to perform administration tasks. Let me know if you’d like some additional posts on this topic and I’ll be all too happy to pursue it further.