list active sessionids

To get a list of all active ASP.NET Session IDs, you can use a combination of code in your Global.asax file and some reflection. Here’s a basic example:

1. Track Sessions in Global.asax:
   • Add session IDs to a list when a session starts.
   • Remove session IDs from the list when a session ends.

public class Global : System.Web.HttpApplication
{
    private static readonly List _sessions = new List();
    private static readonly object padlock = new object();

    public static List Sessions
    {
        get { return _sessions; }
    }

    protected void Session_Start(object sender, EventArgs e)
    {
        lock (padlock)
        {
            _sessions.Add(Session.SessionID);
        }
    }

    protected void Session_End(object sender, EventArgs e)
    {
        lock (padlock)
        {
            _sessions.Remove(Session.SessionID);
        }
    }
}

 

1. Retrieve Active Sessions:
   • Use reflection to access the internal session state.

 

public static IEnumerable GetActiveSessions()
{
    var sessions = new List();
    var obj = typeof(HttpRuntime).GetProperty("CacheInternal", BindingFlags.NonPublic | BindingFlags.Static).GetValue(null, null);
    var obj2 = (object[])obj.GetType().GetField("_caches", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(obj);

    foreach (var cache in obj2)
    {
        var c2 = (Hashtable)cache.GetType().GetField("_entries", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(cache);
        foreach (DictionaryEntry entry in c2)
        {
            var o1 = entry.Value.GetType().GetProperty("Value", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(entry.Value, null);
            if (o1.GetType().ToString() == "System.Web.SessionState.InProcSessionState")
            {
                var sessionId = (string)o1.GetType().GetField("_sessionId", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(o1);
                sessions.Add(sessionId);
            }
        }
    }
    return sessions;
}

 

This approach works for InProc session state mode. If you’re using StateServer or SQLServer modes, you’ll need a different approach as Session_End won’t be triggered12.

Thanks