Simple WMI client

Let's say you need to acquire couple of statistics from remote Windows server. You're not using a fancy utility like HP OVO or something like that, you just need an ad hoc solution, which can't have any component running on the server.

In my case I needed to check on free space, number of processes and available memory on couple of servers. The easiest way to do it, is to use the WMI - Windows Management Instrumentation. It provides SQL-like access to Windows system information. It allows you to inquire on all sorts of various information, for full list of available classes check this MSDN article.

I decided to write a simple command line client in C#, because it would most probably take quite a lot of effort in C and I should broaden the range of languages I use on a daily basis anyway.

using System;
using System.Management;
using System.Globalization;
using System.Net;
using Microsoft.Win32;

class DisplayInfo
{
 public static int Main(string[] args)
 {
  ManagementScope scope;
  ConnectionOptions options = new ConnectionOptions();
  if ((args.Length == 0) || (args[0] == "--help") || (args[0] == "-h") || (args[0] == "/?"))
  {
   Console.WriteLine("wmi - select information from WMI\n\n" + 
       "Usage: wmi WMI_CLASS [servername username password]\n\n" +
       "Most usefull classes are\n" + 
       "\tWin32_OperatingSystem\n" +
       "\tWin32_Share\n" +
       "\tWin32_DiskDrive\n" +
       "\tWin32_LogicalDisk\n" +
       "\tWin32_Process\n");
   return 0;
  }
  else if (args.Length == 1)
  {
   scope = new ManagementScope();
  }
  else
  {
   string server = args[1];

   options.Username = args[2];
   options.Password = args[3];
   options.Authority = "NTLMDOMAIN:"+server;

   scope = new ManagementScope("\\\\"+server+"\\root\\cimv2", options);
  }

  scope.Connect();

  SelectQuery query = new SelectQuery("SELECT * FROM "+args[0]);

  ManagementObjectSearcher s = new ManagementObjectSearcher(scope, query);
  foreach (ManagementObject o in s.Get())
  {
   PropertyDataCollection properties = o.Properties;
   foreach (PropertyData property in properties)
   {
    Console.WriteLine("{0}: {1}", property.Name, o[property.Name]);
   }
   Console.WriteLine();
  }
  Console.WriteLine();
  return 0;
 }
}

It doesn't do any error checking whatsoever, because it assumes you know what you're doing.

Also note the actual query line

SelectQuery query = new SelectQuery("SELECT * FROM "+args[0]);

which allows you to do a nice SQL injection like this

wmi "Win32_LogicalDisk WHERE Name = 'C:'" 

It requires minimum .NET 1.1 and can be easily compiled on any computer with .NET (you don't need any SDK or anything). For convenience binary version can be downloaded - wmi.zip (3kB)

Usage: wmi WMI_CLASS [servername user password]

So if you want for example to inquiry on all the drives and their free space on a remote server, you need to do

wmi Win32_LogicalDisk remote_server remote_user remote_password | grep -i \\\(^FreeSpace\\\)\\\|\\\(^Caption\\\) 

Caption: C:
FreeSpace: 3357395456
Caption: D:
FreeSpace:
Caption: F:
FreeSpace: 3357395456
Caption: H:
FreeSpace: 88749633536
Caption: O:
FreeSpace: 33317158912
Caption: P:
FreeSpace: 33317158912
Caption: Q:
FreeSpace: 2288992256
Caption: S:
FreeSpace: 396537856
Caption: T:
FreeSpace: 2888278016