什么是进程？
当一个程序开始运行时，它就是一个进程，进程包括运行中的程序和程序所使用到的内存和系统资源。
而一个进程又是由多个线程所组成的。
什么是线程？
线程是程序中的一个执行流，每个线程都有自己的专有寄存器(栈指针、程序计数器等)，但代码区是共享的，即不同的线程可以执行同样的函数。
什么是多线程？
多线程是指程序中包含多个执行流，即在一个程序中可以同时运行多个不同的线程来执行不同的任务，也就是说允许单个程序创建多个并行执行的线程来完成各自的任务。
多线程的好处：
可以提高CPU的利用率。在多线程程序中，一个线程必须等待的时候，CPU可以运行其它的线程而不是等待，这样就大大提高了程序的效率。
多线程的不利方面：
线程也是程序，所以线程需要占用内存，线程越多占用内存也越多；
多线程需要协调和管理，所以需要CPU时间跟踪线程；
线程之间对共享资源的访问会相互影响，必须解决竞用共享资源的问题；
线程太多会导致控制太复杂，最终可能造成很多Bug；

接下来将对C#编程中的多线程机制进行探讨。为了省去创建GUI那些繁琐的步骤，更清晰地逼近线程的本质，接下来的所有程序都是控制台程序，程序最后的Console.ReadLine()是为了使程序中途停下来，以便看清楚执行过程中的输出。
任何程序在执行时，至少有一个主线程。
一个直观印象的线程示例：

//SystemThread.cs
using System;
using System.Threading;
namespace ThreadTest
{
class RunIt
　　{
　　　　[STAThread]
static void Main(string[] args)
　　　　{
　　　　　　Thread.CurrentThread.Name="System Thread";//给当前线程起名为"System Thread"
            Console.WriteLine(Thread.CurrentThread.Name+"'Status:"+Thread.CurrentThread.ThreadState);
　　　　　　Console.ReadLine();
　　　　}
　　}
}

输出如下：
System Thread's Status:Running
在这里，我们通过Thread类的静态属性CurrentThread获取了当前执行的线程，对其Name属性赋值“System Thread”，最后还输出了它的当前状态（ThreadState）。
所谓静态属性，就是这个类所有对象所公有的属性，不管你创建了多少个这个类的实例，但是类的静态属性在内存中只有一个。很容易理解CurrentThread为什么是静态的——虽然有多个线程同时存在，但是在某一个时刻，CPU只能执行其中一个。
在程序的头部，我们使用了如下命名空间：
     using System;
     using System.Threading;
在.net framework class library中，所有与多线程机制应用相关的类都是放在System.Threading命名空间中的。如果你想在你的应用程序中使用多线程，就必须包含这个类。
我们通过其中提供的Thread类来创建和控制线程，ThreadPool类用于管理线程池等。
（此外还提供解决了线程执行安排，死锁，线程间通讯等实际问题的机制。）
Thread类有几个至关重要的方法，描述如下：
Start()：启动线程；
Sleep(int)：静态方法，暂停当前线程指定的毫秒数；
Abort()：通常使用该方法来终止一个线程；
Suspend()：该方法并不终止未完成的线程，它仅仅挂起线程，以后还可恢复；
Resume()：恢复被Suspend()方法挂起的线程的执行；

C#多线程学习系列：

C#多线程学习(二) 如何操纵一个线程
http://www.cnblogs.com/xugang/archive/2008/04/06/1138841.html

C#多线程学习(三) 生产者和消费者
http://www.cnblogs.com/xugang/archive/2008/03/23/1118594.html

C#多线程学习(四) 多线程的自动管理(线程池)
http://www.cnblogs.com/xugang/archive/2008/03/23/1118584.html

C#多线程学习(五) 多线程的自动管理(定时器)
http://www.cnblogs.com/xugang/archive/2008/03/23/1118537.html

C#多线程学习(六) 互斥对象
http://www.cnblogs.com/xugang/archive/2008/03/23/1118530.html

相关文章：
DotNet线程问题解答

Visual C#中使用线程

C# 线程资源同步方式总结

C#线程系列讲座(1)：BeginInvoke和EndInvoke方法

.NET将关于多线程的功能定义在System.Threading名称空间中，因此，如果您的程序要使用多线程，必须引用此命名空间(using System.Threading)。
我们知道，在.NET中使用多线程有两种方式：
1，使用Thread创建一个新的线程。
2，使用ThreadPool。

首先我们先说说和Thread有关的几个概念。
1，创建线程和启动线程，如果代码可实现

Thread newThread = new Thread(new ThreadStart(Work.DoWork));
newThread.Start();

或者

Thread newThread = new Thread(new ParameterizedThreadStart(Work.DoWork));
newThread.Start(42);

ParameterizedThreadStart 此委托在 .NET Framework 2.0 版中是新增的
在创建托管的线程时，在该线程上执行的方法将通过一个传递给 Thread 构造函数的 ThreadStart 委托或 ParameterizedThreadStart 委托来表示。
在调用 System.Threading.Thread.Start 方法之前，该线程不会开始执行。执行将从 ThreadStart 或 ParameterizedThreadStart 委托表示的方法的第一行开始。
ParameterizedThreadStart 委托和 Thread.Start(Object) 方法重载使得将数据传递给线程过程变得简单，但由于可以将任何对象传递给 Thread.Start(Object)，因此这种方法并不是类型安全的。
将数据传递给线程过程的一个更可靠的方法是将线程过程和数据字段都放入辅助对象。

下面的代码示例演示通过静态方法和实例方法创建和使用 ParameterizedThreadStart 委托的语法,ThreadStart委托的使用方法和ParameterizedThreadStart一样，
唯一的区别在ThreadStart封装的方法不需要参数。(实例来自MSDN)

using System;
using System.Threading;

public class Work
{
public static void Main()
{
// To start a thread using a shared thread procedure, use
// the class name and method name when you create the
// ParameterizedThreadStart delegate.
//
        Thread newThread = new Thread(
new ParameterizedThreadStart(Work.DoWork));

// Use the overload of the Start method that has a
// parameter of type Object. You can create an object that
// contains several pieces of data, or you can pass any
// reference type or value type. The following code passes
// the integer value 42.
//
        newThread.Start(42);

// To start a thread using an instance method for the thread
// procedure, use the instance variable and method name when
// you create the ParameterizedThreadStart delegate.
//
        Work w = new Work();
        newThread = new Thread(
new ParameterizedThreadStart(w.DoMoreWork));

// Pass an object containing data for the thread.
//
        newThread.Start("The answer.");
    }

public static void DoWork(object data)
{
        Console.WriteLine("Static thread procedure. Data='{0}'",
            data);
    }

public void DoMoreWork(object data)
{
        Console.WriteLine("Instance thread procedure. Data='{0}'",
            data);
    }
}

/**//* This code example produces the following output (the order
   of the lines might vary):

Static thread procedure. Data='42'
Instance thread procedure. Data='The answer'
*/

2，挂起线程
挂起线程分为两种，主动挂起和被动挂起。
主动挂起可表示为：
Thread.Sleep (Int32) 或 Thread.Sleep (TimeSpan) ，表示将当前调用线程挂起指定的时间。
被动挂起表示为：

Thread newThread = new Thread(new ThreadStart(Work.DoWork));
newThread.Start();
newThread.Join();

或者

Thread.CurrentThread.Join(50);

Join表示在继续执行标准的 COM 和 SendMessage 消息泵处理期间，阻止调用线程，直到某个线程终止为止。
在[STAThread]指示的Com线程模型中，我们应该使用Thread.CurrentThread.Join(50)这种方式。有一个与之有关的示例，
Thread.Sleep vs. Thread.CurrentThread.Join

3，终止线程
在调用 Abort 方法以销毁线程时，公共语言运行库将引发 ThreadAbortException。ThreadAbortException 是一种可捕获的特殊异常，但在 catch 块的结尾处它将自动被再次引发。
引发此异常时，运行库将在结束线程前执行所有 finally 块。由于线程可以在 finally 块中执行未绑定计算，或调用 Thread.ResetAbort 来取消中止，所以不能保证线程将完全结束。
如果您希望一直等到被中止的线程结束，可以调用 Thread.Join 方法。Join 是一个模块化调用，它直到线程实际停止执行时才返回。
注意：在托管可执行文件中的所有前台线程已经结束后，当公共语言运行库 (CLR) 停止后台线程时，它不使用 System.Threading.Thread.Abort。
因此，无法使用 ThreadAbortException 来检测 CLR 何时终止后台线程。
下面的示例说明如何中止线程。接收 ThreadAbortException 的线程使用 ResetAbort 方法取消中止请求并继续执行。(示例来自MSDN)

using System;
using System.Threading;
using System.Security.Permissions;

public class ThreadWork {
public static void DoWork() {
try {
for(int i=0; i<100; i++) {
                Console.WriteLine("Thread - working.");
                Thread.Sleep(100);
            }
        }
catch(ThreadAbortException e) {
            Console.WriteLine("Thread - caught ThreadAbortException - resetting.");
            Console.WriteLine("Exception message: {0}", e.Message);
            Thread.ResetAbort();
        }
        Console.WriteLine("Thread - still alive and working.");
        Thread.Sleep(1000);
        Console.WriteLine("Thread - finished working.");
    }
}

class ThreadAbortTest {
public static void Main() {
        ThreadStart myThreadDelegate = new ThreadStart(ThreadWork.DoWork);
        Thread myThread = new Thread(myThreadDelegate);
        myThread.Start();
        Thread.Sleep(100);
        Console.WriteLine("Main - aborting my thread.");
        myThread.Abort();
        myThread.Join();
        Console.WriteLine("Main ending.");
    }
}

这段代码产生以下输出：
Thread - working.
Main - aborting my thread.
Thread - caught ThreadAbortException - resetting.
Exception message: Thread was being aborted.
Thread - still alive and working.
Thread - finished working.
Main ending.

最后还有一点需要说明的是，在.NET Framework 2.0后，Thread对象的Suspend和Resume方法已被摈弃。
原因在于使用 Suspend 和 Resume 方法来同步线程的活动。您无法知道挂起线程时它正在执行什么代码。
如果您在安全权限评估期间挂起持有锁的线程，则 AppDomain 中的其他线程可能被阻止。
如果您在线程正在执行类构造函数时挂起它，则 AppDomain 中试图使用该类的其他线程将被阻止。很容易发生死锁。

1、配置web.config文件：配置数据库连接参数

<configuration>
<appSettings/>
<connectionStrings>
  <add name="ConnectionString" connectionString="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=F:\TeacherSystem\App_Data\db.mdb;Jet OLEDB:Database Password=123"
   providerName="System.Data.OleDb" />
</connectionStrings>

2
程序设计开始：

1、按要求建立Access数据库及数据表

2、编写数据库访问、操作的公用类，此类可以复用到以后开发的任何系统中

（1）、新建一个C# 类库项目， 命名为“Com.LXJ”，设置项目属性：程序集名称、默认命名空间均为“Com.LXJ”

（2）、在此项目目录下创建目录Database，新建C# 类文件ConnDbForAccess.cs 在Database目录下。

              添加引用：System.Web.dll

（3）、编写ConnDbForAccess.cs 的代码

  using System;
using System.Data;
using System.Data.OleDb;
using System.Web;
using System.Web.UI;
using System.Configuration;

namespace Com.LXJ.Database
{
    /// <summary>
    /// conn 的摘要说明。
    /// </summary>
    public class ConnDbForAcccess
    {
        /// <summary>
        /// 连接数据库字符串
        /// </summary>
        private string connectionString;

        /// <summary>
        /// 存储数据库连接（保护类，只有由它派生的类才能访问）
        /// </summary>
        protected OleDbConnection Connection;

        /// <summary>
        /// 构造函数：数据库的默认连接
        /// </summary>
        public ConnDbForAcccess()
        {
            string connStr;
            connStr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString.ToString();
           // connStr = System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"].ToString(); //从web.config配置中读取
            connectionString = connStr;
            //connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + HttpContext.Current.Request.PhysicalApplicationPath + connStr;
           // connectionString = System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"].ToString();
            //
            Connection = new OleDbConnection(connectionString);
        }

        /// <summary>
        /// 构造函数：带有参数的数据库连接
        /// </summary>
        /// <param name="newConnectionString"></param>
        public ConnDbForAcccess(string newConnectionString)
        {
            //connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + HttpContext.Current.Request.PhysicalApplicationPath + newConnectionString;
            connectionString = newConnectionString;
            Connection = new OleDbConnection(connectionString);
        }

        /// <summary>
        /// 获得连接字符串
        /// </summary>
        public string ConnectionString
        {
            get
            {
                return connectionString;
            }
        }

        /// <summary>
        /// 执行SQL语句没有返回结果，如：执行删除、更新、插入等操作
        /// </summary>
        /// <param name="strSQL"></param>
        /// <returns>操作成功标志</returns>
        public bool ExeSQL(string strSQL)
        {
            bool resultState = false;

            Connection.Open();
            OleDbTransaction myTrans = Connection.BeginTransaction();
            OleDbCommand command = new OleDbCommand(strSQL, Connection, myTrans);

            try
            {
                command.ExecuteNonQuery();
                myTrans.Commit();
                resultState = true;
            }
            catch
            {
                myTrans.Rollback();
                resultState = false;
            }
            finally
            {
                Connection.Close();
            }
            return resultState;
        }

        /// <summary>
        /// 执行SQL语句返回结果到DataReader中
        /// </summary>
        /// <param name="strSQL"></param>
        /// <returns>dataReader</returns>
        private OleDbDataReader ReturnDataReader(string strSQL)
        {
            Connection.Open();
            OleDbCommand command = new OleDbCommand(strSQL, Connection);
            OleDbDataReader dataReader = command.ExecuteReader();
            Connection.Close();

            return dataReader;
        }

        /// <summary>
        /// 执行SQL语句返回结果到DataSet中
        /// </summary>
        /// <param name="strSQL"></param>
        /// <returns>DataSet</returns>
        public DataSet ReturnDataSet(string strSQL)
        {
            Connection.Open();
            DataSet dataSet = new DataSet();
            OleDbDataAdapter OleDbDA = new OleDbDataAdapter(strSQL, Connection);
            OleDbDA.Fill(dataSet, "objDataSet");

            Connection.Close();
            return dataSet;
        }

        /// <summary>
        /// 执行一查询语句，同时返回查询结果数目
        /// </summary>
        /// <param name="strSQL"></param>
        /// <returns>sqlResultCount</returns>
        public int ReturnSqlResultCount(string strSQL)
        {
            int sqlResultCount = 0;

            try
            {
                Connection.Open();
                OleDbCommand command = new OleDbCommand(strSQL, Connection);
                OleDbDataReader dataReader = command.ExecuteReader();

                while (dataReader.Read())
                {
                    sqlResultCount++;
                }
                dataReader.Close();
            }
            catch
            {
                sqlResultCount = 0;
            }
            finally
            {
                Connection.Close();
            }
            return sqlResultCount;
        }

    }//
}//

好了，数据库访问、数据库操作的公用类完成了，详细代码意义大家自己看吧，这些属于C# 语法知识了，现在可以编译生成项目了，编译完后把项目的dll文件Com.LXJ.dll拷贝到Example项目下的bin目录中，然后在项目 Example中引入Com.LXJ.dll即可。稍后介绍如何使用它，休息一下，喝口水，呵呵.....

办公

OpenOffice - office suite
PC Suite 602 - office suite
AbiWord - text editor
Atlantis Nova - text editor
Microsoft PowerPoint Viewer - power point files viewer
Adobe Reader - pdf reader
Foxit PDF Reader - pdf reader
PDFCreator - create pdf documents
Doc Convertor - document convertor
Convert - unit convertor
Converber - unit convertor
Sunbird - calendar/organizer
EssentialPIM Free - calendar/organizer
PhraseExpress - speed up your writing
ATnotes - create notes on the desktop

解压缩

7-Zip - compression program
IZArc - compression program
TugZIP - compression program
CabPack - compression program
Universal Extractor - extract files from any type of archive

互联网

Firefox - web browser
Internet Explorer- web browser
Maxthon - web browser
Opera - web browser
Avant Browser - web browser
Thunderbird - email client
PopTray - check for emails
Free Download Manager - download manager
FlashGet - download manager
WellGet - download manager
Download Master - download manager
WGET - commandline download manager
HTTrack - offline browser
WebReaper - offline browser
Yeah Reader - RSS reader
GreatNews - RSS reader
RSSOwl - RSS reader

P2P

µTorrent - torrent client
Azureus - torrent client
BitComet - torrent client
ABC - torrent client
BitTornado - torrent client
eMule - p2p client
SoulSeek - p2p client
Shareaza - p2p client
DC++ - Direct Connect network client
PeerGuardian - IP blocker

聊天

Miranda - chat client
MSN Messenger - chat client
Yahoo Messenger - chat client
QIP - chat client
Gaim - chat client
JAJC - chat client
HydraIRC - IRC client
Talkative IRC - IRC client
IceChat - IRC client
Skype - VOIP client
Google Talk - VOIP client
VoipStunt - VOIP client
Gizmo - VOIP client
Wengo - VOIP client

安全

AVG Free - antivirus
Avast Home Free - antivirus
AntiVir PersonalEdition - antivirus
BitDefender Free - antivirus
ClamWin - antivirus
CyberDifender - Internet Security Suite
Ad-aware - anti-spyware
Spybot: Search & Destroy - anti-spyware
Windows Defender - anti-spyware
SpywareBlaster - anti-spyware
Spyware Terminator - anti-spyware
Tootkit Reveaker - rootkit detection utility
Winpooch - system protection
HiJack Free - system protection
HighJackThis - hijackers detector and remover
Kerio Personal Firewall - firewall
Sygate Personal Firewall - firewall
ZoneAlarm - firewall
AxCrypt - file encryption
Simple File Shredder - securely delete files
PuTTy - SSH client
KeePass - password manager
LockNote - password manager
nPassword - password manager
Microsoft Baseline Security Analyzer - identify security misconfigurations

网络

Hamachi - VPN client
RealVNC - remote control
UltraVNC - remote control
Ethereal - local area network administration
The Dude - network administration
Wireshark - network administration
Angry IP Scanner - IP scanner
IP-Tools - IP scanner
Free Port Scanner - IP scanner
NetMeter - network bandwidth monitoring

服务器

FileZilla - FTP client
FileZilla Server - FTP server
EFTP - FTP client/server
XAMPP - integrated server package of Apache, mySQL, PHP and Perl
WAMP - Apache, PHP5 and MySQL server

音频

Foobar2000 - audio player
WinAmp - audio player
1by1 - audio player
JetAudio - audio player
XMPlay - audio player
Xion - audio player
Apollo - audio player
MediaMonkey - music organizer
The GodFather - music organizer
dBpowerAMP - audio converter
Audacity - audio converter
WavePad - audio converter
Kristal Audio Engine - audio editor
Exact Audio Copy - CD ripper
Audiograbber - CD ripper
CDex - CD ripper
Mp3 Tag Tools - tag editor
Mp3tag - tag editor
Taggin’ MP3 - tag editor
Monkey’s Audio - APE compressor/decompressor
mpTrim - mp3 editor
WavTrim - wave editor
EncSpot Basic - analyse mp3 files

视频

Windows Media Player - audio/video player
VLC - video player
Media Player Classic - video player
MV2Player - video player
CrystalPlayer 1.95 - video player
Zoom Player - video player
GOM Player - video player
viPlay - video player
DSPlayer - video player
VirtualDub - video editor
CamStudio - video screen recording
AviSplit - Avi splitter
Video mp3 Extractor - rip audio from video files
Free iPod Converter - convert all popular video formats to iPod video
MediaPortal - turning your PCinto a Media Center
The FilmMachine

图像

Gimp - image editor
PhotoFiltre - image editor
Paint.net - image editor
ArtRage - image editor
Artweaver - image editor
IrfanView - image viewer
Picasa - image viewer
XnView - image viewer
FastStone Image Viewer - image viewer
FuturixImager - image viewer
Easy Thumbnails - create thumbnails from images
JoJoThumb - create thumbnails from images
iWebAlbum - create web photo albums
JAlbum - create web photo albums
3D Box Shot Maker - design quality box shot
FastStone Capture - screen capture
WinSnap - screen capture

3D

Blender3D - 3D renderer
3Delight Free - 3D renderer
SketchUp - 3D modeling
Maya Learning Edition - 3D modeling

开发

AutoIt - task automation
SciTE4AutoIt3 - text editor for AutoIt
AutoHotkey - task automation
PHP Designer - PHP editor
Notepad++ - text editor
ConTEXT Editor - text editor
PSPad - text editor
FoxEditor - text editor
Crimson Editor - source code editor
Elfima Notepad - text editor
Notepad2 - text editor
Nvu - HTML editor
Alleycode - HTML editor
BlockNote - web page editor
Weaverslave - web page editor

CD/DVD

DeepBurner - CD/DVD burner
CDBurner XP Pro - CD/DVD burner
BurnAtOnce - CD/DVD burner
Express Burn - CD/DVD burner
Zilla CD-DVD Rip’n’Burn - CD/DVD
刻录
ImgBurn - ISO, BIN burner
Daemon tools - virtual CD/DVD
DVD Decrypter - DVD ripper
DVD Shrink - DVD ripper
Nero CD-DVD Speed - CD/DVD info and quality test
解码

GSpot - codec information
AC3Filter - audio codec
Xvid - video codec
QuickTime Alternative - video codec
Real Alternative - video codec
K-Lite Codec Pack - all codecs

系统工具

CCleaner - system cleaner
xp-AntiSpy - OS setup
jv16 Powertools - system utilities
XP SysPad - system monitoring utility
What’s Running - process guard
Registrar Lite - registry editor
WinIPConfig - replacement for “ipconfig.exe” and “route.exe”
Unlocker - file eraser
Eraser - secure file eraser
Undelete Plus - file recovery
freeCommander - file manager
ExplorerXP - file manager
Duplicate File Finder - find all duplicate files
Ant Renamer - file renaming
ReNamer - file renaming
Icons From File - icos extractor
Chaos MD5 - MD5 generator
HashTab - MD5, SHA1 and CRC-32 file hashes
Rainlendar Lite - desktop calendar
Weather Watcher - weather firecast
Subtitle Workshop - subtitles editor
Ant Movie Catalog - movie organizer
Disclib - CD organizer
Dexpot - virtual desktops
DriveImage XML - create partition images
MozBackup - backup and restore bookmarks, etc.
SyncBack - system backup
Atomic Cock Sync - syncronize your clock
Citrus Alarm Clock - alarm clock
TaskSwitchXP - Alt-Tab replacement
Launchy - application launcher
allSnap - make all windows snap
Sysinternals Tools - various system tools
StrokeIt - mouse gestures
Net Profiles - create profiles of your network settings
ResourceHacker - view, modify, rename, add, delete
Java Runtime Environment - java for Windows

UI设计

RocketDock - application launcher
AveDesk - desktop enhancer
IconPhile - customize windows’s system icons
CursorXP Free - change mouse cursors
MacSound - volume control
LClock - Windows Longhorn clock
Y’z Dock - application launcher
Y’z Shadow - shadow effect to the windows
Y’z Toolbar - change the toolbar icons in Explorer and Internet Explorer
Taskbar Shuffle - rearrange the programs on the taskbar by dragging
Visual Task Tips - thumbnail preview image for each task in the taskbar
Badges - put badges on any folder or file
Folderico - change icons of the folders
Folder Marker - mark your folders
Folder2MyPC - add favourite locations to My Computer
Microsoft TweakUI - system settings
BricoPacks - shell packs
ShellPacks - shell packs
Tango Shell Patcher - shell patcher
XPize - GUI enhancer
Vista Transformation Pack - complete visual style
Vista Sound Scheme - Windows Vista sound scheme
Royale Theme - visual style

硬件检测

CPU-Z - cpu information
CrystalCPUID - cpu information
Central Brain Identifier - cpu information
Everest - system information
SiSoft Sandra - system information
SpeedFan - hardware monitor
Memtest86 - memory test
PowerMax - HDD test
3Dmark 06 - 3D game performance benchmark
Aquamark - performance benchmark
rthdribl - 3D benchmark
Fraps - 3D benchmark, fps viewer and screen recorder
Prime 95 - cpu benchmarking
SuperPI - cpu benchmarking
CPU Rightmark - cpu overclock
Core Temp - cpu temperature
ATiTool - video overclock
ATI Tray Tools - Radeon tweaker
aTuner - GeForce and Radeontweaker
RivaTuner - video overclock
Nokia Monitor Test - monitor adjustmets
UDPixel - fix dead pixels

游戏

123 Free Solitaire - solitaire games collection
Arcade Pack - classic arcade games
Live For Speed - online racing simulator
Enigma - puzzle game
Freeciv - multiplayer strategy game
Tux Racer - race down steep, snow-covered mountains

教育

SpeQ Mathematics - mathematics program
Dia - diagram creation program
Google Earth - explore the world
NASA World Wind - 3D virtual globe
Celestia - explore the space
Stellarium - planetarium

杂类

nLite - Build your own custom Windows disk.
VirtualPC - create virtual machines
grabMotion - webcam capture
iDailyDiary - simple page-for-a-day diary
Pivot Stickfigure Animator - create stick-figure animations
Wink - create presentations
Scribus - professional page layout
FreeMind - midn mapping software
Windows Live Writer - WYSIWYG blog authoring

墙纸

Michael Swanson - 1920 x 1200; 1600 x 1200; amazing wallpapers
出处：17Tech.Com

[   ] Blind MySQL injection and database stressing
      http://www.reversing.org/node/view/13
[   ] Using SQLBrute to brute force data from a blind SQL injection point
      http://www.justinclarke.com/archives/2006/03/sqlbrute.html
[   ] Advanced SQL Injection In SQL Server Applications - Chris Anley <chris@ngssoftware.com> [2002]
      http://www.nextgenss.com/papers/advanced_sql_injection.pdf
[   ] (more) Advanced SQL Injection - Chris Anley <chris@ngssoftware.com> [2002-06-18]
      http://www.nextgenss.com/papers/more_advanced_sql_injection.pdf
[   ] SQL Injection, Are Your Web Applications Vulnerable? - SPI Dynamics [2004-10-29]
      http://www.securitydocs.com/library/2656
      http://www.securitydocs.com/link.php?action=detail&id=2656&headerfooter=no
      http://www.securitydocs.com/pdf/2656.PDF
[   ] Manipulating Microsoft SQL Server Using SQL Injection - Cesar Cerrudo <sqlsec@yahoo.com>
      http://www.appsecinc.com/presentations/Manipulating_SQL_Server_Using_SQL_Injection.pdf
[   ] Top 15 free SQL Injection Scanners
      http://www.security-hacks.com/2007/05/18/top-15-free-sql-injection-scanners
      SQLIer
      http://bcable.net/project.php?sqlier
      Sqlbftools
      http://www.reversing.org/node/view/11
      SQLibf
      http://www.open-labs.org/ (这里有一些HTTP相关的工具)
      SQL Brute
      http://www.gdssecurity.com/l/t.php
      BobCat
      http://www.northern-monkee.co.uk/index.html
      http://www.northern-monkee.co.uk/projects/bobcat/bobcat.html
      sqlmap
      http://sqlmap.sourceforge.net/
      Absinthe
      http://www.0x90.org/releases/absinthe/
      http://www.0x90.org/releases/absinthe/download.php
      SQL Injection Pentesting TooL
      http://sqltool.itdefence.ru/indexeng.html
      http://sqltool.itdefence.ru/setup.rar
      SQID
      http://sqid.rubyforge.org/
      http://rubyforge.org/frs/?group_id=2617
      SQL Power Injector
      http://sourceforge.net/projects/spinj/
      http://www.sqlpowerinjector.com/
      FG-Injector Framework
      http://sourceforge.net/projects/injection-fwk/
      sqlninja
      http://sqlninja.sourceforge.net/
      Automagical SQL injector
      http://www.indianz.ch/tools/attack/automagic.zip
      NGSS SQL Injector
      http://www.indianz.ch/tools/attack/sqlinjector.zip
      ISR-sqlget
      http://www.infobyte.com.ar/
      http://www.infobyte.com.ar/down/ISR-sqlget-1.0.0.tar.gz
      http://www.infobyte.com.ar/down/ISR-sqlget-Readme.txt
      http://www.infobyte.com.ar/demo/ISR_sqlget_ISS_proventia_bypass.html
      ISR-Form
      http://www.infobyte.com.ar/down/ISR-form-v1.0.tar.gz
      BlindMap
      http://www.c0debreak.net/cb/main.html
      http://codebreak.uni.cc/cb/papers/blind.html
      http://codebreak.uni.cc/downloads/sql.zip
      http://external.c0debreak.net/files/sql.zip
      http://w4ck1ng.com/tools/sql/sql.zip
      BaKo's SQL Injection Scanner v2.2 - BaKo [2007-11-29]
      http://files.h4ck-y0u.org/3745771
[   ] Web application vulnerability scanner / security auditor
      http://wapiti.sourceforge.net/
[   ] w3af - Web Application Attack and Audit Framework
      http://w3af.sourceforge.net/
[   ] advanced web server fingerprinting
      http://www.computec.ch/projekte/httprecon/
      (有windows版)
[   ] http://chorizo-scanner.com/
[   ] OWASP SQLiX Project
      http://www.owasp.org/index.php/Category:OWASP_SQLiX_Project

From OWASP

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This is an Attack. To view all attacks, please see the Attack Category page.

Last revision: 7/2/2008

Description

LDAP Injection is an attack used to exploit web based applications that construct LDAP statements based on user input. When an application fails to properly sanitize user input, it’s possible to modify LDAP statements using a local proxy. This could result in the execution of arbitrary command such as granting permissions to unauthorized queries, and content modification inside the LDAP tree. The same advanced exploitation techniques available in SQL Injection can be similarly applied in LDAP Injection.

Examples

Example 1

In a page with a user search form, the following code is responsible to catch input value and generate a LDAP query that will be used in LDAP database.

 <input type="text" size=20 name="userName">Insert the username</input> 

The LDAP query is narrowed down for performance and the underlying code for this function might be the following:

 String ldapSearchQuery = "(cn=" + $userName + ")";
 System.out.println(ldapSearchQuery); 

Case the variable $userName is not validated, it could be possible accomplish LDAP injection, as follows:

*If a user puts “*” on box search, the system may return all the usernames on the LDAP base
*If a user puts “jonys) (| (password = * ) )”, it will generate the code bellow revealing jonys’ password
( cn = jonys ) ( | (password = * ) )

Example 2

The following vulnerable code is used in an ASP web application which provides login with LDAP data base. On line 11, the variable userName is initialized and validated to check if it’s not in blank. Then, the content of this variable is used to construct a LDAP query used by SearchFilter on line 28. The attacker has the chance specify what will be queried on LDAP server, and see the result on the line 33 to 41, are all results and their attributes are displayed.

Commented vulnerable asp code:

 
 1.	<html>
 2.	<body>
 3.	<%@ Language=VBScript %>
 4.	<%
 5.	Dim userName
 6.	Dim filter
 7.	Dim ldapObj
 8.		
 9.	Const LDAP_SERVER = "ldap.example"
 10.	
 11.	userName = Request.QueryString("user")
 12.	
 13.	if( userName = "" ) then
 14.	Response.Write("Invalid request. Please specify a valid
 15.	user name")
 16.	Response.End()
 17.	end if
 18.	
 19.	filter = "(uid=" + CStr(userName) + ")" ' searching for the  user entry 
 20.	
 21.	'Creating the LDAP object and setting the base dn
 22.	Set ldapObj = Server.CreateObject("IPWorksASP.LDAP")
 23.	ldapObj.ServerName = LDAP_SERVER
 24.	ldapObj.DN = "ou=people,dc=spilab,dc=com"
 25.	
 26.	'Setting the search filter
 27.	ldapObj.SearchFilter = filter
 28.	
 29.	ldapObj.Search
 30.	
 31.	'Showing the user information
 32.	While ldapObj.NextResult = 1
 33.	Response.Write("<p>")
 34.	
 35.	Response.Write("<b><u>User information for: " + 
 36.	ldapObj.AttrValue(0) + "</u></b><br>")
 37.	For i = 0 To ldapObj.AttrCount -1
 38.	Response.Write("<b>" + ldapObj.AttrType(i) +"</b>: " +
 39.	ldapObj.AttrValue(i) + "<br>" )
 40.	Next
 41.	Response.Write("</p>")
 42.	Wend
 43.	%>
 44.	</body>
 45.	</html>   

In the example above, we send the * character in the user parameter which will result in the filter variable in the code to be initialized with (uid=*). The resulting LDAP statement will make the server return any object that contains a uid attribute like username.

 http://www.some-site.org/index.asp?user=*  

Related Threat Agents

• Category: Insider

Related Attacks

• Interpreter Injection
• SQL Injection
• Command Injection
• Relative Path Traversal
• Resource Injection
• Path Manipulation

Related Vulnerabilities

Category:Input Validation Vulnerability

Related Controls

• Category:Input Validation

References

• http://www.blackhat.com/presentations/bh-europe-08/Alonso-Parada/Whitepaper/bh-eu-08-alonso-parada-WP.pdf

• http://www.ietf.org/rfc/rfc1960.txt A String Representation of LDAP Search Filters (RFC1960)

• http://www.redbooks.ibm.com/redbooks/SG244986.html IBM RedBooks - Understanding LDAP

• http://www.webappsec.org/projects/threat/classes/ldap_injection.shtml

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Categories: OWASP ASDR Project | Injection | Attack