User Agent中文名为用户代理，简称 UA，它是一个特殊字符串头，使得服务器能够识别客户使用的操作系统及版本、CPU 类型、浏览器及版本、浏览器渲染引擎、浏览器语言、浏览器插件等。
一些网站常常通过判断 UA 来给不同的操作系统、不同的浏览器发送不同的页面，因此可能造成某些页面无法在某个浏览器中正常显示。比如一些钓鱼站点，也会判断终端类型，推送不同的内容。比如下面这个钓鱼站，在PC上访问，只会给你一句提示，而换在手机上访问，就可以看到它的完全内容了。
用PC访问的样子
用手机访问的样子
那么，我们要怎么在PC上看到手机才能看到的内容捏，那就可以通过修改user-agent来实现了。下面总结三种方法。
第一种:Chrome浏览器自带功能
Chrome浏览器->F12->ctrl+shift+M->选择终端->访问网站
第二种：Firefox浏览器插件
安装user-agent switcher插件->选择终端设置->访问网站
第三种www.58yuanyou.com：Burp Suite改包
浏览器设置代理->开启BurpSuite->抓包->改包
将红线处的user-agent参数换掉即可
附常见UserAgent
PC端的UserAgent
safari 5.1 – MAC
User-Agent:Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_8; en-us)AppleWebKit/534.50 (KHTML, like Gecko) Version/5.1 Safari/534.50
safari 5.1 – Windows
User-Agent:Mozilla/5.0 (Windows; U; Windows NT 6.1; en-us) AppleWebKit/534.50(KHTML, like Gecko) Version/5.1 Safari/534.50
Firefox 38esr
User-Agent:Mozilla/5.0 (Windows NT 10.0; WOW64; rv:38.0) Gecko/20100101Firefox/38.0
IE 11
User-Agent:Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; .NET4.0C;.NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.30729; .NET CLR 3.5.30729;InfoPath.3; rv:11.0) like Gecko
IE 9.0
User-Agent:Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0;
IE 8.0
User-Agent:Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0)
IE 7.0
User-Agent:Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)
IE 6.0
User-Agewww.58yuanyou.comnt: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
Firefox 4.0.1 – MAC
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0.1)Gecko/20100101 Firefox/4.0.1
Firefox 4.0.1 – Windows
User-Agent:Mozilla/5.0 (Windows NT 6.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
Opera 11.11 – MAC
User-Agent:Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; en) Presto/2.8.131Version/11.11
Opera 11.11 – Windows
User-Agent:Opera/9.80 (Windows NT 6.1; U; en) Presto/2.8.131 Version/11.11
Chrome 17.0 – MAC
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_0) AppleWebKit/535.11(KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11
傲游（Maxthon）
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Maxthon 2.0)
腾讯TT
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; TencentTraveler4.0)
世界之窗（The World） 2.x
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)
世界之窗（The World） 3.x
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; The World)
搜狗浏览器 1.x
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; SE2.X MetaSr 1.0; SE 2.X MetaSr 1.0; .NET CLR 2.0.50727; SE 2.X MetaSr 1.0)
360浏览器
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; 360SE)
Avant
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Avant Browser)
Green Browser
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)
移动原由网端UserAgent
safari iOS 4.33 – iPhone
User-Agent:Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_www.58yuanyou.com3 like Mac OS X; en-us)AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2Safari/6533.18.5
safari iOS 4.33 – iPod Touch
User-Agent:Mozilla/5.0 (iPod; U; CPU iPhone OS 4_3_3 like Mac OS X; en-us)AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2Safari/6533.18.5
safari iOS 4.33 – iPad
User-Agent:Mozilla/5.0 (iPad; U; CPU OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9(KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5
Android N1
User-Agent: Mozilla/5.0 (Linux; U; Android 2.3.7; en-us; Nexus One Build/FRF91)AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Android QQ浏览器 For android
User-Agent: MQQBrowser/26 Mozilla/5.0 (Linux; U; Android 2.3.7; zh-cn; MB200Build/GRJ22; CyanogenMod-7) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0Mobile Safari/533.1
Android Opera Mobile
User-Agent: Opera/9.80 (Android 2.3.4; Linux; Opera Mobi/build-1107180945; U;en-GB) Presto/2.8.149 Version/11.10
Android Pad Moto Xoom
User-Agent: Mozilla/5.0 (Linux; U; Android 3.0; en-us; Xoom Build/HRI39)AppleWebKit/534.13 (KHTML, like Gecko) Version/4.0 Safari/534.13
BlackBerry
User-Agent: Mozilla/5.0 (BlackBerry; U; BlackBerry 9800; en) AppleWebKit/534.1+(KHTML, like Gecko) Version/6.0.0.337 Mobile Safari/534.1+
WebOS HP Touchpad
User-Agent: Mozilla/5.0 (hp-tablet; Linux; hpwOS/3.0.0; U; en-US)AppleWebKit/534.6 (KHTML, like Gecko) wOSBrowser/233.70 Safari/534.6TouchPad/1.0
Nokia N97
User-Agent: Mozilla/5.0 (SymbianOS/9.4; Series60/5.0 NokiaN97-1/20.0.019;Profile/MIDP-2.1 Configuration/CLDC-1.1) AppleWebKit/525 (KHTML, like Gecko)BrowserNG/7.1.18124
Windows Phone Mango
User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows Phone OS 7.5;Trident/5.0; IEMobile/9.0; HTC; Titan)
UC无
User-Agent: UCWEB7.0.2.37/28/999
UC标准
User-Agent: NOKIA5700/ UCWE原由网B7.0.2.37/28/999
UCOpenwave
User-Agent: Openwave/ UCWEB7.0.2.37/28/999
UC Opera
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; ) Opera/UCWEB7.0.2.37/28/999