ab是apache自帶的一個很好用的壓力測試工具，當安裝完apache的時候，就可以在bin下面找到ab

1 我們可以模擬100個併發使用者，對一個頁面傳送1000個請求

./ab -n1000 -c100 http://www.baidu.com

其中-n代表請求數，-c代表併發數

返回結果:

##首先是apache的版本資訊
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking vm1.jianfeng.com (be patient)

Server Software:        Apache/2.2.19    ##apache版本
Server Hostname:        vm1.jianfeng.com   ##請求的機子
Server Port:            80 ##請求埠

Document Path:          /a.html
Document Length:        25 bytes  ##頁面長度

Concurrency Level:      100  ##併發數
Time taken for tests:   0.273 seconds  ##共使用了多少時間
Complete requests:      1000   ##請求數
Failed requests:        0   ##失敗請求
Write errors:           0  
Total transferred:      275000 bytes  ##總共傳輸位元組數，包含http的頭資訊等
HTML transferred:       25000 bytes  ##html位元組數，實際的頁面傳遞位元組數
Requests per second:    3661.60 [#/sec] (mean)  ##每秒多少請求，這個是非常重要的引數數值，伺服器的吞吐量
Time per request:       27.310 [ms] (mean)  ##使用者平均請求等待時間
Time per request:       0.273 [ms] (mean, across all concurrent requests)  ##伺服器平均處理時間，也就是伺服器吞吐量的倒數
Transfer rate:          983.34 [Kbytes/sec] received  ##每秒獲取的資料長度

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    1   2.3      0      16
Processing:     6   25   3.2     25      32
Waiting:        5   24   3.2     25      32
Total:          6   25   4.0     25      48

Percentage of the requests served within a certain time (ms)
  50%     25  ## 50%的請求在25ms內返回
  66%     26  ## 60%的請求在26ms內返回
  75%     26
  80%     26
  90%     27
  95%     31
  98%     38
  99%     43
100%     48 (longest request)

2 ab也可以執行在windows中，如果在windows下安裝apache,就可以在bin下找到ab.exe

直接就可以使用，不用依賴其他的dll

下面是我使用ab.exe 測試新浪一個頁面的結果：

C:\Users\nickyjf\Desktop\useful>ab -n1000 -c100 http://sports.sina.com.cn/k/2011-05-24/12095590365.shtml
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking sports.sina.com.cn (be patient)
Completed 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Completed 500 requests
Completed 600 requests
Completed 700 requests
Completed 800 requests
Completed 900 requests
Completed 1000 requests
Finished 1000 requests

Server Software:        Apache/2.0.63
Server Hostname:        sports.sina.com.cn
Server Port:            80

Document Path:          /k/2011-05-24/12095590365.shtml
Document Length:        86680 bytes

Concurrency Level:      100
Time taken for tests:   66.453 seconds
Complete requests:      1000
Failed requests:        0
Write errors:           0
Total transferred:      87135790 bytes
HTML transferred:       86680000 bytes
Requests per second:    15.05 [#/sec] (mean)
Time per request:       6645.294 [ms] (mean)
Time per request:       66.453 [ms] (mean, across all concurrent requests)
Transfer rate:          1280.51 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        1   56 398.3      2    3003
Processing:    89 6331 2603.7   6293   14626
Waiting:        2 1748 1485.9   1590    6284
Total:         90 6388 2615.0   6302   14627

Percentage of the requests served within a certain time (ms)
  50%   6302
  66%   7121
  75%   8435
  80%   9193
  90%   9231
  95%   9385
  98%  11549
  99%  12459
100%  14627 (longest request)

3 apache的ab工具也算是一種ddos攻擊工具