防封禁策略

Scrapy:

http://doc.scrapy.org/en/master/topics/practices.html#avoiding-getting-banned

如何让你的scrapy爬虫不再被ban

根据scrapy官方文档：http://doc.scrapy.org/en/master/topics/practices.html#avoiding-getting-banned里面的描述，要防止scrapy被ban，主要有以下几个策略。

由于Google cache受国内网络的影响，你懂得；所以主要从动态随机设置user agent、禁用cookies、设置延迟下载和使用代理IP这几个方式。

本文以cnblogs为例

  • 创建middlewares.py　　scrapy代理IP、user agent的切换都是通过DOWNLOADER_MIDDLEWARES进行控制，下面我们创建middlewares.py文件。
  1. 编辑 `middlewares.py`
  1. [root@bogon cnblogs]# vi cnblogs/middlewares.py

如下内容：

  1. import random
  2. import base64
  3. from settings import PROXIES
  5. class RandomUserAgent(object):
  6.     """Randomly rotate user agents based on a list of predefined ones"""
  8.     def __init__(self, agents):
  9.         self.agents = agents
  11.     @classmethod
  12.     def from_crawler(cls, crawler):
  13.         return cls(crawler.settings.getlist('USER_AGENTS'))
  15.     def process_request(self, request, spider):
  16.         #print "**************************" + random.choice(self.agents)
  17.         request.headers.setdefault('User-Agent', random.choice(self.agents))
  19. class ProxyMiddleware(object):
  20.     def process_request(self, request, spider):
  21.         proxy = random.choice(PROXIES)
  22.         if proxy['user_pass'] is not None:
  23.             #request.meta['proxy'] = "http://YOUR_PROXY_IP:PORT"
  24.             request.meta['proxy'] = "http://%s" % proxy['ip_port']
  25.             #proxy_user_pass = "USERNAME:PASSWORD"
  26.             encoded_user_pass = base64.encodestring(proxy['user_pass'])
  27.             request.headers['Proxy-Authorization'] = 'Basic ' + encoded_user_pass
  28.             print "**************ProxyMiddleware have pass************" + proxy['ip_port']
  29.         else:
  30.             print "**************ProxyMiddleware no pass************" + proxy['ip_port']
  31.             request.meta['proxy'] = "http://%s" % proxy['ip_port']

类RandomUserAgent主要用来动态获取user agent，user agent列表USER_AGENTS在settings.py中进行配置。

类ProxyMiddleware用来切换代理，proxy列表PROXIES也是在settings.py中进行配置。

如果你用的是socks5代理，那么对不起，目前scrapy还不能直接支持，可以通过Privoxy等软件将其本地转化为http代理

  • 修改settings.py配置USER_AGENTS和PROXIES
  1. a)：添加USER_AGENTS
  1. USER_AGENTS = [
  2.     "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; AcooBrowser; .NET CLR 1.1.4322; .NET CLR 2.0.50727)",
  3.     "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; Acoo Browser; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506)",
  4.     "Mozilla/4.0 (compatible; MSIE 7.0; AOL 9.5; AOLBuild 4337.35; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)",
  5.     "Mozilla/5.0 (Windows; U; MSIE 9.0; Windows NT 9.0; en-US)",
  6.     "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 2.0.50727; Media Center PC 6.0)",
  7.     "Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 1.0.3705; .NET CLR 1.1.4322)",
  8.     "Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 5.2; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506.30)",
  9.     "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN) AppleWebKit/523.15 (KHTML, like Gecko, Safari/419.3) Arora/0.3 (Change: 287 c9dfb30)",
  10.     "Mozilla/5.0 (X11; U; Linux; en-US) AppleWebKit/527+ (KHTML, like Gecko, Safari/419.3) Arora/0.6",
  11.     "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2pre) Gecko/20070215 K-Ninja/2.1.1",
  12.     "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9) Gecko/20080705 Firefox/3.0 Kapiko/3.0",
  13.     "Mozilla/5.0 (X11; Linux i686; U;) Gecko/20070322 Kazehakase/0.4.5",
  14.     "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.8) Gecko Fedora/1.9.0.8-1.fc10 Kazehakase/0.5.6",
  15.     "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11",
  16.     "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_3) AppleWebKit/535.20 (KHTML, like Gecko) Chrome/19.0.1036.7 Safari/535.20",
  17.     "Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; fr) Presto/2.9.168 Version/11.52",
  18. ]
  1. b)：添加代理IP设置PROXIES
  1. PROXIES = [
  2.     {'ip_port': '111.11.228.75:80', 'user_pass': ''},
  3.     {'ip_port': '120.198.243.22:80', 'user_pass': ''},
  4.     {'ip_port': '111.8.60.9:8123', 'user_pass': ''},
  5.     {'ip_port': '101.71.27.120:80', 'user_pass': ''},
  6.     {'ip_port': '122.96.59.104:80', 'user_pass': ''},
  7.     {'ip_port': '122.224.249.122:8088', 'user_pass': ''},
  8. ]

代理IP可以网上搜索一下，上面的代理IP获取自：http://www.xici.net.co/

  1. c)：禁用cookies
  1. COOKIES_ENABLED=False
  1. d)：设置下载延迟
  1. DOWNLOAD_DELAY=3
  1. e)：最后设置DOWNLOADER_MIDDLEWARES 
  1. DOWNLOADER_MIDDLEWARES = {
  2.     'cnblogs.middlewares.RandomUserAgent': 1,
  3.     'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware': 110,
  4.     'cnblogs.middlewares.ProxyMiddleware': 100,
  5. }

保存settings.py

3、测试

  1. [root@bogon cnblogs]# scrapy crawl CnblogsSpider

本文的user agent和proxy列表都是采用settings.py的方式进行设置的，实际生产中user agent和proxy有可能会经常更新，每次更改配置文件显得很笨拙也不便于管理。因而，可以根据需要保存在mysql数据库