Month of Lunches - Day 10

Remote Control: One to One, and One to Many. This chapter is all about the remote functions of PowerShell and how to use them.

Don mentions something in the first part of this chapter that I noticed when I started with the help files in chapter 3. I got really excited when I saw the -computername parameter in the help file for Get-Service but didn’t really see to many in some of the other commands. This was strange to me because I know that PowerShell has a very powerful remoteing capability from everything that I have read.

So how does it work? In a nutshell you are pushing the commands out across the network and they are running on the remote machines and sending the information back to your console. PowerShell is using a specific service call WinRM. Now the really cool part about this is that all of PowerShells remote traffic is carried over HTTP and HTTPS protocols, and all of the return PowerShell objects are being converted to xml.

Configuring WinRM for PowerShell is a fairly straightforward process and must be done on every machine that you want to run remote commands on. If you only have a few to do or are in a workgroup then you can just call the Enable-PSRemoting cmdlet. Basically what this command does is start the WinRm Service and its startup type to auto, sets up PowerShell as a user of WinRM, and will even set a firewall rule allowing winrm traffic. Now if you are on a domain you can make this super easy and just use a Group Policy Object template, or if your servers are 2008 r2 then the settings are built right in. They are located in: Computer Configuration/Administrative Templates/Windows Components/Remote Shell and Windows Remote Management.

To start a one-to-one connection in PowerShell use the Enter-PSSession cmdlet (I bet you didn’t know to close it you would use the inverse, Exit command: ) then you just specify the -computername parameter and away you go. Easy right. One of the best parts is it passes your local account for authentication and you will wind up with the same permissions on the remote computer (if your running as admin locally it will run your shell as admin on the remote system).

If you want to use one-to-many remoting then the next section is for you. As Don puts it in the book, this is full scale distributed computing. The cmdlet that does this is Invoke-Command. You can specify the remote computers with the computername parameter.

                Examples: Invoke-Command -Computername wkstn1,wkstn2,server1,server2,server3 -command (get-service)

                Invoke-Command -Computer (get-content c:\list.txt) -command {get-eventlog -newest 100) |  {where -property entrytype -   eq error}}

The really cool part about this last command is that the remote computers are processing all of the information, all at the exact same time, and your admin workstation is receiving all the info. Nothing more than collections is being done on your local machine. How cool is that. I cant wait to test this on a domain : )

There is so much more to cover that I am going to have to write a second post when I actually get a chance to implement and test the remote capabilities. Ill report back but until then have a great day.