/// <summary>
/// Retrieves all objects from the given DN and returns their given properties
/// 
/// If we are told to search recursively then if we find any OU's we iterate through those
/// as well
/// </summary>
/// <param name="DN"></param>
/// <param name="properties"></param>
/// <param name="useRecursion"></param>
/// <returns></returns>
public static List<string> GetAllObjects(string DN, List<string> properties, bool useRecursion)
{
    var results = new List<string>();

    // Certain values from the AD search are
    // date/time values. Because of their format
    // we need to convert them into something that
    // we can understand.
    //
    // The following is a short list I use to 
    // convert any of those dates. 
    //
    // Any dates not listed here will not be converted
    var dates = new List<string>()
    {
        "pwdLastSet",
        "badPasswordCountTime",
        "lastLogoff",
        "lastLogon",
        "lastLogonTimestamp",
        "lockoutTime"
    };

    try
    {
        DirectoryEntry de = new DirectoryEntry("LDAP://" + DN);
        foreach (DirectoryEntry child in de.Children)
        {

            // If we require recursion, this is the place to do it
            //
            // We need to remove the LDAP:// header though because 
            // we will re-add it automatically
            if (child.Properties.Contains("ou"))
            {
                if (useRecursion) results.AddRange(GetAllObjects(child.Path.Remove(0, 7), properties, useRecursion));
            }
            else
            {
                var propertySb = new StringBuilder();

                var lcounter = 0;

                // Since we accept property inputs we need to make sure those
                // are what we capture from the search.
                //
                // In our case we don't return the entire property list if the properties are
                // empty. If no properties are specified then no results will be returned
                foreach (var property in properties)
                {
                    var val = "";
                    if (child.Properties.Contains(property))
                    {
                        if(dates.Contains(property))
                        {
                            var t = child.Properties[property].Value;
                            var ticks = GetInt64(child, property);
                            var dateFormattedValue = DateTime.FromFileTime(ticks);
                            val = dateFormattedValue.ToString();
                        }
                        else
                        {
                            val = child.Properties[property].Value.ToString();
                        }

                        if (val != property)
                        {
                            if (lcounter + 1 == properties.Count)
                            {
                                propertySb.Append(val);
                            }
                            else
                            {
                                propertySb.Append(val + ",");
                            }
                        }
                    }

                    lcounter++;
                }

                results.Add(propertySb.ToString());
            }


            child.Close();
            child.Dispose();
        }

        de.Close(); de.Dispose();

    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.ToString());
    }

    return results;
}

/// <summary>
/// Given a directory entry and the property we are looking at
/// we can convert the illegible timestamp into a format
/// that can be parsed by the DateTime class.
/// </summary>
/// <param name="entry"></param>
/// <param name="attr"></param>
/// <returns></returns>
private static Int64 GetInt64(DirectoryEntry entry, string attr)
{
    DirectorySearcher ds = new DirectorySearcher(
      entry,
      String.Format("({0}=*)", attr),
      new string[] { attr },
      SearchScope.Base
      );

    SearchResult sr = ds.FindOne();

    if (sr != null)
    {
        if (sr.Properties.Contains(attr))
        {
            return (Int64)sr.Properties[attr][0];
        }
    }
    return -1;
}

/// <summary>
/// Retrieves all objects from the given DN and returns their given properties
/// 
/// If we are told to search recursively then if we find any OU's we iterate through those
/// as well
/// </summary>
/// <param name="DN"></param>
/// <param name="properties"></param>
/// <param name="useRecursion"></param>
/// <returns></returns>
public static List<string> GetAllObjects(string DN, List<string> properties, bool useRecursion)
{
    var results = new List<string>();

    // Certain values from the AD search are
    // date/time values. Because of their format
    // we need to convert them into something that
    // we can understand.
    //
    // The following is a short list I use to 
    // convert any of those dates. 
    //
    // Any dates not listed here will not be converted
    var dates = new List<string>()
    {
        "pwdLastSet",
        "badPasswordCountTime",
        "lastLogoff",
        "lastLogon",
        "lastLogonTimestamp",
        "lockoutTime"
    };

    try
    {
        DirectoryEntry de = new DirectoryEntry("LDAP://" + DN);
        foreach (DirectoryEntry child in de.Children)
        {

            // If we require recursion, this is the place to do it
            //
            // We need to remove the LDAP:// header though because 
            // we will re-add it automatically
            if (child.Properties.Contains("ou"))
            {
                if (useRecursion) results.AddRange(GetAllObjects(child.Path.Remove(0, 7), properties, useRecursion));
            }
            else
            {
                var propertySb = new StringBuilder();

                var lcounter = 0;

                // Since we accept property inputs we need to make sure those
                // are what we capture from the search.
                //
                // In our case we don't return the entire property list if the properties are
                // empty. If no properties are specified then no results will be returned
                foreach (var property in properties)
                {
                    var val = "";
                    if (child.Properties.Contains(property))
                    {
                        if(dates.Contains(property))
                        {
                            var t = child.Properties[property].Value;
                            var ticks = GetInt64(child, property);
                            var dateFormattedValue = DateTime.FromFileTime(ticks);

                            if (property == "pwdLastSet")
                            {
                                val = dateFormattedValue.ToString() + "; Expires @ " + Dates.ModifySingle(dateFormattedValue.ToString(), "42");
                            }
                            else
                            {
                                val = dateFormattedValue.ToString();
                            }
                        }
                        else
                        {
                            val = child.Properties[property].Value.ToString();
                        }

                        if (val != property)
                        {
                            if (lcounter + 1 == properties.Count)
                            {
                                propertySb.Append(val);
                            }
                            else
                            {
                                propertySb.Append(val + ",");
                            }
                        }
                    }

                    lcounter++;
                }

                results.Add(propertySb.ToString());
            }


            child.Close();
            child.Dispose();
        }

        de.Close(); de.Dispose();

    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.ToString());
    }

    return results;
}

/// <summary>
/// Given a directory entry and the property we are looking at
/// we can convert the illegible timestamp into a format
/// that can be parsed by the DateTime class.
/// </summary>
/// <param name="entry"></param>
/// <param name="attr"></param>
/// <returns></returns>
private static Int64 GetInt64(DirectoryEntry entry, string attr)
{
    DirectorySearcher ds = new DirectorySearcher(
      entry,
      String.Format("({0}=*)", attr),
      new string[] { attr },
      SearchScope.Base
      );

    SearchResult sr = ds.FindOne();

    if (sr != null)
    {
        if (sr.Properties.Contains(attr))
        {
            return (Int64)sr.Properties[attr][0];
        }
    }
    return -1;
}

Retrieving objects from Active Directory

directory

C#