Python之DNS

DNS

dnspython(http://www.dnspython.org/) 是Python实现的一个DNS工具包，它支持几乎所有的记录类型，可以用于查询、传输并动态更新ZONE信息，同时支持TSIG(事务签名)验证消息和EDNS0(扩展DNS).在系统方面,我们可以利用其查询功能来实现DNS服务监控以及解析结果的校验,可以代替nslookup及dig等工具，轻松做到与现有平台的整合

安装

pip install dnspython

DNS记录解析

• A记录，将主机名转换成IP地址
• MX记录，邮件交换记录，定义邮件服务器的域名
• CNAME记录，指别名记录，实现域名间的映射
• NS记录，标记区域的域名服务器及授权子域
• PTR记录，反向解析，与A记录相反，将IP转换成主机名
• SOA记录，SOA标记，一个起始授权区的定义

A记录

# codeing=utf-8
import dns.resolver

domain = raw_input("Please input an domain: ")
A = dns.resolver.query(domain,'A')
for i in A.response.answer:
        for j in i.items:
                print j.address

MX记录

# coding=utf-8

import dns.resolver
domain = raw_input('Please input an domain: ')

MX = dns.resolver.query(domain, 'MX')
for i in MX:
    print 'MX preference =', i.preference, 'mail exchanger =', i.exchange

Please input an domain: 163.com      
MX preference = 10 mail exchanger = 163mx02.mxmail.netease.com.
MX preference = 10 mail exchanger = 163mx01.mxmail.netease.com.
MX preference = 50 mail exchanger = 163mx00.mxmail.netease.com.
MX preference = 10 mail exchanger = 163mx03.mxmail.netease.com.

NS记录

# coding=utf-8
import dns.resolver
print '*************NS****************'
domain = raw_input('Please input an domain: ')
ns = dns.resolver.query(domain, 'NS')
for i in ns.response.answer:
     for j in i.items:
          print j.to_text()
        
*************NS****************
Please input an domain: baidu.com
ns4.baidu.com.
dns.baidu.com.
ns2.baidu.com.
ns7.baidu.com.
ns3.baidu.com.

CNAME记录

# coding=utf-8
import dns.resolver
print '****************CNAME****************'
domain = raw_input('Please input an domain: ')
 
cname = dns.resolver.query(domain, 'CNAME')
for i in cname.response.answer:
    for j in i.items:
        print j.to_text()

****************CNAME****************
Please input an domain: www.baidu.com
www.a.shifen.com.

综合案例

import dns.resolver
import httplib
 
iplist = []  # 定义域名IP列表变量
# appdomain = "www.google.com.hk"  # 定义业务域名
appdomain = "www.baidu.com"  # 定义业务域名
 
# 域名解析函数，解析成功IP将追加到iplist
def get_iplist(domain=""):
    try:
        A = dns.resolver.query(domain, 'A')  # 解析A记录类型
    except Exception, e:
        print "dns resolver error:" + str(e)
        return
    for i in A.response.answer:
        for j in i.items:
            iplist.append(j.address)  # 追加到iplist
    return True
 
 
def checkip(ip):
    checkurl = ip + ":80"
    getcontent = ""
    httplib.socket.setdefaulttimeout(5)  # 定义http连接超时时间(5秒)
    conn = httplib.HTTPConnection(checkurl)  # 创建http连接对象
 
    try:
        conn.request("GET", "/", headers={"Host": appdomain})  # 发起URL请求，添加host主机头
        r = conn.getresponse()
        getcontent = r.read(15)  # 获取URL页面前15个字符，以便做可用性校验
    finally:
        if getcontent.lower() == "":  # 监控URL页的内容一般是事先定义好，比如“HTTP200”等
            print ip + " [OK]"
        else:
            print ip + " [Error]"  # 此处可放告警程序，可以是邮件、短信通知
 
 
if __name__ == "__main__":
    if get_iplist(appdomain) and len(iplist) > 0:  # 条件：域名解析正确且至少要返回一个IP
        for ip in iplist:
            checkip(ip)
    else:
        print "dns resolver error."