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A realtime event log monitoring tool

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27 Aug 2003CPOL2 min read 369.7K   11.7K   110   73
Demonstrates how to do realtime event log monitoring

Image 1

Introduction

I'm an instant gratification kind of person. I like to see who and from where my machine is being accessed, as it occurs. This tool allows you to do just that and provides a number of other event log monitoring capabilities.

Background

While testing a piece of software that provides Windows event logging, our QA team questioned if there was a way to monitor events as they are written to the Windows event log, hence the creation of this little utility. The notifications that the tool displays are done so using the most-excellent NotifyIconEx class by Joel Matthias.

Capturing Events

The EventLog class contains an event handler called EntryWritten. This handler expects an argument of type EntryWrittenEventArgs. To capture events as they happen, we simply set the EnableRaisingEvents property to true and declare the method name that will handle the event.

C#
private void StartWatch()
{      
  EventLog myLog = new EventLog(watchLog);
        
  // set event handler
  myLog.EntryWritten += new EntryWrittenEventHandler(OnEntryWritten);
  myLog.EnableRaisingEvents = true;
}

Displaying Events

When events that match the specified criteria occur, a balloon notification is displayed with the details of the last event that was written. (To capture and display Security log events, you must have auditing turned on.)

C#
private void OnEntryWritten(object source, EntryWrittenEventArgs e)
{
  string logName = watchLog;
  GetLogEntryStats(watchLog);
  
  if (logType == eventFilter || eventFilter.Length == 0)
  {
    // show balloon
    NotifyIcon.ShowBalloon("Event Log Monitor",
      "An event was written to the "+logName+" event log."+
      "\nType: "+LogType+
      "\nSource: "+LogSource+
      "\nCategory: "+LogCategory+
      "\nEventID: "+EventID+
      "\nUser: "+User,
      NotifyIconEx.NotifyInfoFlags.Info,
      5000);
        
    LogNotification();
  }
}
    
private void GetLogEntryStats(string logName)
{
  int e = 0;
  
  EventLog log = new EventLog(logName);
  e = log.Entries.Count - 1; // last entry

  logMessage = log.Entries[e].Message;
  logMachine = log.Entries[e].MachineName;
  logSource = log.Entries[e].Source;
  logCategory = log.Entries[e].Category;
  logType = Convert.ToString(log.Entries[e].EntryType);
  eventID = log.Entries[e].EventID.ToString();
  user = log.Entries[e].UserName;
  logTime = log.Entries[e].TimeGenerated.ToShortTimeString();
  log.Close();  // close log
}

The GetEventLogs() method provides an overload for retrieving the logs from a remote machine. It is feasible to assume that event monitoring should work the same on a remote machine as it does on the local computer, given the appropriate permissions. As time permits, I'll be expanding the filtering capabilities of the tool and provide the ability to monitor multiple machines.

Compatibility Issues

The code has only been tested on Windows XP SP1 but should run on Windows 2000. However, while the NotifyIconEx class contains an event handler called BalloonClick, this isn't supported on Windows 2000. Will not work on Win9x or NT4 as they are incapable of displaying balloon notifications.

History

  • Version 1.0 - 08.22.2003

  • License

    This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


    Written By
    Zambia Zambia
    Living abroad and loving life.

    Comments and Discussions

     
    GeneralRe: Excellent.. How about reading more than one log automatically??? Pin
    gman4414-May-04 15:08
    gman4414-May-04 15:08 
    GeneralEvent logging in Win9X Pin
    CAmelinckx21-Apr-04 3:28
    CAmelinckx21-Apr-04 3:28 
    GeneralProblem with EntryWritten Event Pin
    Steffen20035-Nov-03 5:19
    Steffen20035-Nov-03 5:19 
    GeneralI've taken your code and made a tool... Pin
    NewtonTroy17-Oct-03 9:28
    NewtonTroy17-Oct-03 9:28 
    GeneralRe: I've taken your code and made a tool... Pin
    AdrianBromley22-Oct-03 6:22
    AdrianBromley22-Oct-03 6:22 
    GeneralRe: I've taken your code and made a tool... Pin
    Christian Merritt22-Oct-03 6:31
    Christian Merritt22-Oct-03 6:31 
    GeneralNice, but... Pin
    Stoyan Damov29-Aug-03 5:17
    Stoyan Damov29-Aug-03 5:17 
    GeneralRe: Nice, but... Pin
    Christian Merritt29-Aug-03 8:04
    Christian Merritt29-Aug-03 8:04 
    Yes, it's possible. The way it's implemented, a newer event could be written to the log between the time the event is fired and when the balloon is displayed.

    As you pointed out, the method will return the last log entry it finds, but not necessarily the one that triggered the event... I'll be updating this functionality in the future. Thanks for the feedback. Big Grin | :-D
    GeneralRe: Nice, but... Pin
    Stoyan Damov29-Aug-03 11:48
    Stoyan Damov29-Aug-03 11:48 
    GeneralRe: Nice, but... Pin
    Richard Deeming5-Sep-03 7:40
    mveRichard Deeming5-Sep-03 7:40 
    GeneralRe: Nice, but... Pin
    mrshizeats19-Jan-04 4:32
    mrshizeats19-Jan-04 4:32 

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