百度爬虫
    * Baiduspider+(+http://www.baidu.com/search/spider.htm”)

google爬虫
    * Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
    * Googlebot/2.1 (+http://www.googlebot.com/bot.html)
    * Googlebot/2.1 (+http://www.google.com/bot.html)

雅虎爬虫（分别是雅虎中国和美国总部的爬虫）
    *Mozilla/5.0 (compatible; Yahoo! Slurp China; http://misc.yahoo.com.cn/help.html)
    *Mozilla/5.0 (compatible; Yahoo! Slurp; http://help.yahoo.com/help/us/ysearch/slurp)

新浪爱问爬虫
    *iaskspider/2.0(+http://iask.com/help/help_index.html”)
    *Mozilla/5.0 (compatible; iaskspider/1.0; MSIE 6.0)

搜狗爬虫
    *Sogou web spider/3.0(+http://www.sogou.com/docs/help/webmasters.htm#07)
    *Sogou Push Spider/3.0(+http://www.sogou.com/docs/help/webmasters.htm#07)

网易爬虫
    *Mozilla/5.0 (compatible; YodaoBot/1.0;http://www.yodao.com/help/webmaster/spider/;)

MSN爬虫
    *msnbot/1.0 (+http://search.msn.com/msnbot.htm)