Windows Powershell Remoting

Windows Powershell has always offered much promise but with version 1.0 at least often failed to deliver when you got into the detail. In contrast version 2 seems to offer more hope particularly when combined with the remote management feature that comes as standard with Windows Server 2008 R2 and is available as a download for R1.

My evaluation project was to use Powershell to obtain disk space, audit failures in the security event log and an instant processor reading on a couple of remote servers via a web service over HTTP(S).

The first step was to set up a ‘Listener’ on each of the remote servers for which there is “quick config” option that lets you automatically alter the relevant services, registry keys and other options to get you up and running. Making the changes manually isn’t too difficult if the quick config fails as it did for me.

Stage 2 was to establish a connection or session to each of my remote servers from my PC. There are plenty of options for this stage including authorisation and port number but nothing too complicated. The most difficult part was to get the password used for each session to be read from a file rather than needing to type it in each time. Powershell doesn’t allow you to store your password in plain text which although a ‘good’ thing hinders testing and evaluation.

The final stage was to issue the commands themselves. This proved to be extremely simple with the invoke-command and then either by using Powershell builtin commandlets or via WMI.

Of course the above has been possible before, even with vbscript, but Powershell offers some advantage over its predecessors, not least the following.

• Commands issued to multiple servers run in parallel rather than sequentially.
• A command can run in the background.
• Powershell is extremely good at formatting output allowing the returned data to be easily read.
• The remote connection is over HTTP(S) which is useful for servers in remote data centres or even in the cloud, e.g. with Amazon’s EC2.
• The remote server listener can be configured to expose a limited set of functionality. Hence even someone with administrative credentials is restricted in the information they can gather.

My overall impression of Powershell 2, particularly the remoting feature is that it is now at the level where it is consistently useful. I’m looking forward to version 3, assuming there will be one.