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
下載鏈接：
Linux/Mac：http://httpd.apache.org/download.cgi#apache24
Windows：http://www.apachehaus.com/cgi-bin/download.plx
下載後解壓，並追加PATH環境變量，如";E:\software\Apache24\bin"
1、我們可以模擬100個併發用戶，對一個頁面發送1000個請求ab -n1000 -c100 http://vm1.jianfeng.com/a.html
其中-n代表請求數，-c代表併發數
返回結果:
##首先是apache的版本信息
This is ApacheBench, Version 2.3 <$Revision: 1796539 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/
Benchmarking 127.0.0.1 (be patient)
Completed 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Completed 500 requests
Completed 600 requests
Completed 700 requests
Completed 800 requests
Completed 900 requests
Completed 1000 requests
Finished 1000 requests
Server Software: Apache-Coyote/1.1 ##apache版本
Server Hostname: 127.0.0.1 ##請求的機子
Server Port: 8080 ##請求端口
Document Path: /
Document Length: 1825 bytes ##頁面長度
Concurrency Level: 100 ##併發數
Time taken for tests: 0.273 seconds ##共使用了多少時間
Complete requests: 1000 ##請求數
Failed requests: 0 ##失敗請求
Total transferred: 275000 bytes ##總共傳輸字節數，包含http的頭信息等
HTML transferred: 25000 bytes ##html字節數，實際的頁面傳遞字節數
Requests per second: 3661.60 [#/sec] (mean) ##每秒多少請求，這個是非常重要的參數數值，服務器的吞吐量
Time per request: 27.310 [ms] (mean) ##用戶平均請求等待時間
Time per request: 0.273 [ms] (mean, across all concurrent requests) ##服務器平均處理時間，也就是服務器吞吐量的倒數
Transfer rate: 983.34 [Kbytes/sec] received ##每秒獲取的數據長度
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 1 2.3 0 16
Processing: 6 25 3.2 25 32
Waiting: 5 24 3.2 25 32
Total: 6 25 4.0 25 48
Percentage of the requests served within a certain time (ms)
50% 25 ## 50%的請求在25ms內返回
66% 26 ## 60%的請求在26ms內返回
75% 26
80% 26
90% 27
95% 31
98% 38
99% 43
100% 48 (longest request)
2、ab也可以運行在windows中，如果在windows下安裝apache,就可以在bin下找到ab.exe
直接就可以使用，不用依賴其他的dll
下面是我使用ab.exe 測試一個頁面的結果：
C:\Users\Ricky>ab -n1000 -c100 http://live.fuzhuxian.com/
This is ApacheBench, Version 2.3 <$Revision: 1796539 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/
Benchmarking live.fuzhuxian.com (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-Coyote/1.1
Server Hostname: live.fuzhuxian.com
Server Port: 80
Document Path: /
Document Length: 187 bytes
Concurrency Level: 100
Time taken for tests: 59.833 seconds
Complete requests: 1000
Failed requests: 0
Total transferred: 424000 bytes
HTML transferred: 187000 bytes
Requests per second: 16.71 [#/sec] (mean)
Time per request: 5983.334 [ms] (mean)
Time per request: 59.833 [ms] (mean, across all concurrent requests)
Transfer rate: 6.92 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 40 60 6.0 60 80
Processing: 60 5621 1037.3 5912 5996
Waiting: 60 2973 1718.5 2976 5965
Total: 130 5681 1037.1 5972 6056
Percentage of the requests served within a certain time (ms)
50% 5972
66% 5987
75% 6000
80% 6006
90% 6020
95% 6031
98% 6040
99% 6046
100% 6056 (longest request)
3、apache的ab工具也算是一種ddos攻擊工具。
文章主要參考：http://www.cnblogs.com/yjf512/archive/2011/05/24/2055723.html