The greatest challenge to any thinker is stating the problem in a way that will allow a solution

Bertrand Russell

Welcome to vBlog, a personal record of my techy tinkerings and particular ponderings.

I tend to focus on VMware virtualisation, and the interaction/automation of it using PowerCLI (VMware's PowerShell Snapin), but anything that I happen to stumble across that seems like it might be of use at a later date, may well get recorded here.

I also maintain vWiki, which was a predecessor to this blog. Wiki's are great for quickly recording snippets of info, but tend not to look that great; Blog's are better looking things, but seem to require more effort so that the posts/articles are accessible in their own right. As a result I tend to update both interchangeably as available time, and depth of thought, permit.

If you happen to find anything of use, or in need of correction please leave a comment. Knowing that my ramblings are of some use is a great reward; and similarly I'd hate to waste anybody's time by feeding them duff info.

See these pages for me info about me, and my vBlog, and below for my recent posts...

17 Sep 2013

PowerShell

1 comment

Trying to compare the members of Windows domain Security or Distribution groups cans be a bit of a pain, especially when you’ve got nested groups. To make life a bit easier I wrote a quick script that will go through the members of the groups you want, including unlimited sub-groups (see note below). The script creates a nice grid output table, which you can sort/filter etc. Continue reading →

The logs that the Windows DHCP Server creates for client IP requests are only retained for a week. Which is a bit of a problem if you’re trying to investigate some activity on the network that occurred over 7 days ago. You can retain the logs for longer but you need to archive them off yourself.

The script below archives all available logs to a place of your choosing, and can optionally archive IP v6 logs as well. Continue reading →

28 Jun 2013

PowerShell

3 comments

It is, from time to time, useful to be able to see what is being printed via your print server.  Be it to identify busy printers, heavy users, or in order to keep an eye on what kind of documents are being printed.

This is relatively easy to achieve, but you do need to enable the appropriate logging on your server, as the info isn’t recorded by default.  To display the information in a easy to digest format, requires a few lines of PowerShell as well. Continue reading →

This script utilises a free 3rd party .NET library in order to be able to run SNMP queries from within PowerShell.  I created it in order to be able to keep track of the creation and usage of DHCP scopes during a migration project, and meant that I could instantly find out how short or not we were of available IP addresses.  Longer term you’d obviously want to set-up proper monitoring.

For more info on setting up the SNMP .NET library see my vWiki page – http://vwiki.co.uk/SNMP_and_PowerShell.  Its quite simple.  You have to download the binary package, extract and find the SharpSnmpLib.dll file, then load that into your PowerShell session and hey presto – you have SNMP functionality in PowerShell! Continue reading →

This post provides an example of how to gather some basic system info from an SNMP enabled host using PowerShell.

Why wouldn’t I use WMI?

You could in many circumstances.  In general the amount of information you can get from WMI is far greater than what’s available via SNMP, however,

  • In order to access WMI you often end up requiring full admin rights on the target systems, which is a security nightmare.
  • WMI is Windows platform dependant, whereas SNMP is normally available for any enterprise device.

Continue reading →

I wasn’t particularly waiting for the latest version of PowerShell to arrive.  Version 2 was doing me just fine, however by luck I happened to be playing with a .NET library that required .NET v4.  .NET 4 isn’t officially supported by PowerShell 2, you can force it, but it comes with a few caveats and cautions.  However, PowerShell 3 does support .NET 4, which meant all I had to do was upgrade PowerShell.

In my very limited time using PowerShell v3 there’s one thing that stands out: the Integrated Scripting Environment (ISE) has been vastly improved… Continue reading →

A while back I discovered a SNMP .NET offering that (given that PowerShell is .NET) meant that I could use PowerShell as a SNMP client, which I’ve documented on my Wiki – http://vwiki.co.uk/SNMP_and_PowerShell.

At the time my intended aim for the ability disappeared, and so I never really got to put into use.  This post brings together a couple of techniques in order to achieve regular SNMP polling of a device.  The results of which go into an RRD database (you don’t need to do this, what you do with the results of the SNMP polls is up to you). Continue reading →

I manage a number of Vyatta routers, for which the config changes irregularly.  And whilst I do keep an offline copy of their configs, I do this in a manual fashion, which means its not done reliably, which means its not a reliable backup solution.

Hence I crafted a simple PowerShell script which takes a backup of the routers config if its changed since the last backup… Continue reading →

3 Apr 2012

VMware

5 comments

With SSH access to your ESX servers, it is relatively easy to get the driver and firmware software revision versions that are running (see further reading section at bottom of post).  Which is fine for a one-off inspection, but if you want review your entire ESX estate, this can be quite tedious.

With the wonder of PowerCLI, it is possible to gain most of this information from your vCentre, which will have sourced the information from your ESX through its hardware CIM provider.  But the quality of data returned in this manner varies, you can get…

  • No data (if you server vendor hasn’t fully implemented CIM to cover the server and peripheral devices, or you haven’t installed the CIM provider software, even if you can get data for X and Y, Z may be missing, for example HBA firmware on all HP servers I’ve had the pleasure of looking after)
  • Duplicate data (if you’ve upgraded software you can sometimes get both old and new versions reported)
  • Inconsistent data (representations vary between manufacturers/vendors, so dealing with different makes or even models from the same manufacturer is problematic)

I do all reporting through PowerShell and PowerCLI scripts, and had got fed up with having to tinker with my scripts to try and never fully trusting the data I was seeing.  But more recently I’ve been using PowerShell to act as an SSH client, so decided to take a different approach…
Continue reading →

28 Mar 2012

PowerShell

5 comments

Catchy title, eh?

I make quite extensive use of the NAT’ing functionality of Vyatta routers, and it can be quite a pain in the task to keep track of servers’ real (local) and NAT’ed (remote) IP addresses.

Therefore I have the need to collate all the address translations into a central report, in an easy (aka scripted) fashion.  There are probably other ways of achieving this, but for me its a PowerShell script that SSH’s to each Vyatta router in order to query it… Continue reading →