首先，推荐一个 socks4/socks5 代理的网站，由百度，小米的工程师创办，非常棒！

米扑代理： http://proxy.mimvp.com

脚本主要验证代理IP的可用性，还有三个知识点：

1、随机获取代理ip，通过代理ip访问指定站点，其目的是防止ip被封

2、访问一个页面后，随机休息几秒再访问，其目的是防止网站前面有4-7层过滤设备拦截

3、修改http的User-Agent字段，有些网站和4-7层设备会检查

代码示例：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#
# http://www.mimvp.com
# 2015-01-10

'''
检测代理 IP 的响应时间（ping），验证proxy是否可用
检测代理 IP 是否返回数据，验证Ping通是否可用
'''

import os
import urllib2
import random
import json

import sys
reload(sys)
sys.setdefaultencoding('utf-8')


PROXY_LIST = [
              {'https':"https://64.31.22.131:7808"},
              {'http':"http://77.70.29.176:81"},
              {'http':"http://41.223.119.156:3128"},
              {'http':"http://188.138.247.175:8080"},
              {'https':"https://217.33.193.179:3128"},
              
              {'http':"http://221.10.102.199:82"},
              {'https':"https://119.188.94.145:80"},
              {'https':"https://120.236.148.113:3128"},
              
              {'http':"http://183.209.236.152:8123"},
              {'http':"http://113.56.149.118:8088"}
            ]

USER_AGENT_LIST = [
                'Mozilla/5.0 (Windows; U; Windows NT 5.1; it; rv:1.8.1.11) Gecko/20071127 Firefox/2.0.0.11',
                'Opera/9.25 (Windows NT 5.1; U; en)',
                'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)',
                'Mozilla/5.0 (compatible; Konqueror/3.5; Linux) KHTML/3.5.5 (like Gecko) (Kubuntu)',
                'Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.12) Gecko/20070731 Ubuntu/dapper-security Firefox/1.5.0.12',
                'Lynx/2.8.5rel.1 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/1.2.9'
            ]

# 使用代理访问网站 - GET方式实现
def spider_url_by_get(proxy=None):
    url = 'http://127.0.0.1:8090/'
#     url = 'http://localhost:8888/'
#     url = 'http://localhost/proxy_client/test/test_proxy.php'
    
#     proxy = random.choice(PROXY_LIST)
    print 'proxy : ', proxy

    try:
        proxyHandler = urllib2.ProxyHandler(proxy)
        cookies = urllib2.HTTPCookieProcessor()
        opener = urllib2.build_opener(cookies, proxyHandler, urllib2.HTTPHandler)
        urllib2.install_opener(opener)
        req = urllib2.Request(url)
        
        user_agent = random.choice(USER_AGENT_LIST)
        req.add_header('User-Agent', user_agent)
        data = urllib2.urlopen(req, timeout=10).read()
        
        dataJson = json.loads(str(data), encoding='utf-8')
    #     dataJson['user_agent'] = str(user_agent)
    #     dataJson['proxy'] = str(proxy)
          
        data = json.dumps(dataJson)
        print 'spider_url_by_get（） +++++++++ ', data
    except Exception, ex:
        print 'spider_url_by_get（） -------- ', str(ex)


# 使用代理访问网站 - POST方式实现
def spider_url_by_post():
    pass


def ping_ip(ip=None):
    ping_cmd = 'ping -c 2 -w 5 %s' % ip
    
#     ping_result = os.system(ping_cmd)
#     print 'ping_cmd : %s, ping_result : %r' % (ping_cmd, ping_result)
#     
#     if ping_result == 0:
#         print 'ping %s ok' % ip
#         return True
#     else:
#         print 'ping %s fail' % ip
        
        
    ping_result = os.popen(ping_cmd).read()
    print 'ping_cmd : %s, ping_result : %r' % (ping_cmd, ping_result)
    
    if ping_result.find('100% packet loss') < 0:
        print 'ping %s ok' % ip
        return True
    else:
        print 'ping %s fail' % ip
        
        
def main():
    for proxy in PROXY_LIST:
        for key in proxy.keys():
            value = proxy.get(key, '')
            ip = value.split("//")[1].split(":")[0].strip()
            
            if ping_ip(ip):
                spider_url_by_get(proxy)
                

if __name__ == '__main__':
    main()