Every once and awhile you will probably encounter a situation where you need to enable and then use telnet in a security focused environment. In certain situations telnet can be a great tool to test the functionality of firewall rule. Iif you aren’t certain whether or not a rule is working telnet can be a great way to help debug. The problem in Server 2008 and above is that telnet isn’t enabled by default. Luckily with PowerShell it is easy to enable the telnet functionality.
The following set of commands is a quick depiction of how you can enable telnet from a PowerShell prompt to ensure the ability of testing certain ports. Try it out.
Import-Module servermanager
Add-WindowsFeature telnet-client
Bam! As always, it is always easier to stay in command prompt and this is a great way to test port connectivity. I can understand why telnet is disabled by default on fresh server builds but sometimes it can become useful to have telnet as a tool to test connectivity. If you would like to debate the merits of disabling/enabling telnet on a server just drop me a line, I obviously will not be focusing on this aspect here. Anyway, just as easily as it is to enable telnet through PowerShell it can be disabled with the following command. If you already have the server manager module imported, skip to the second command.
Import-Module servermanager
Remove-WindowsFeature telnet-client
That’s all it takes. Very simple and very straightforward.
For more tips and tricks as well as general information about how PowerShell works, check out the venerable Learn Windows PowerShell in a Month of Lunches
This book is one of my top recommendations on the book recommendations page, especially for learning Powershell and Windows administration.
