2

所以，当谈到 python 时，我仍然处于菜鸟级别。我知道...我知道...可能有一种更有效的方法来做我正在尝试但仍在学习的事情，希望我会通过练习变得更好。

对于一个培训项目，我正在编写一个脚本来对域执行各种 DNS 操作。我找到了 DNSPython，它似乎正是我需要使用的，我以为我已经完成了它，但是当我针对不同的域尝试它时，它在区域传输中一直失败。

我现在有两个域进行硬编码以进行测试。megacorpone 域 iw 正在按我的预期工作，但是现在它失败了（没有代码更改）为了让它工作我必须过滤返回的第一条记录“@”，否则它也会失败。

但是，zonetransfer.me 域有时会以错误完成脚本，但偶尔也会出错，但由于某种原因它从不显示主机记录，而且我还无法弄清楚如何修复它，一直在敲我的头现在反对它一段时间。

megacoprone 运行之前每次都在工作，现在它根本不工作。到目前为止，我唯一能想到的就是这可能是一个时间问题。

用megacoprone运行

Attempting zone transfers for megacorpone.com
Traceback (most recent call last):
  File "/home/kali/Exercises/Module_7/dns-axfer.py", line 56, in zoneXFR
    zone = dns.zone.from_xfr(dns.query.xfr(str(server).rstrip('.'), domain))
  File "/usr/lib/python3/dist-packages/dns/zone.py", line 1106, in from_xfr
    for r in xfr:
  File "/usr/lib/python3/dist-packages/dns/query.py", line 627, in xfr
    raise TransferError(rcode)
dns.query.TransferError: Zone transfer error: REFUSED

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/kali/Exercises/Module_7/dns-axfer.py", line 73, in <module>
    zoneXFR()
  File "/home/kali/Exercises/Module_7/dns-axfer.py", line 66, in zoneXFR
    print ("\nResults for",server, "\nZone origin:", str(zone.origin).rstrip('.'))
UnboundLocalError: local variable 'zone' referenced before assignment

使用 zonetransfer.me 运行 1

Attempting zone transfers for zonetransfer.me

Results for nsztm1.digi.ninja. 
Zone origin: zonetransfer.me
---------------------------------------------------------------------------

Results for nsztm1.digi.ninja. 
Zone origin: zonetransfer.me
---------------------------------------------------------------------------
[*]  Error: <class 'dns.resolver.NoAnswer'> The DNS response does not contain an answer to the question: _acme-challenge.zonetransfer.me. IN A

Results for nsztm2.digi.ninja. 
Zone origin: zonetransfer.me
---------------------------------------------------------------------------

Results for nsztm2.digi.ninja. 
Zone origin: zonetransfer.me
---------------------------------------------------------------------------
[*]  Error: <class 'dns.resolver.NoAnswer'> The DNS response does not contain an answer to the question: _acme-challenge.zonetransfer.me. IN A

在不更改代码的情况下运行 2 (zonetransfer.me)

Attempting zone transfers for zonetransfer.me
Traceback (most recent call last):
  File "/home/kali/Exercises/Module_7/dns-axfer.py", line 56, in zoneXFR
    zone = dns.zone.from_xfr(dns.query.xfr(str(server).rstrip('.'), domain))
  File "/usr/lib/python3/dist-packages/dns/zone.py", line 1106, in from_xfr
    for r in xfr:
  File "/usr/lib/python3/dist-packages/dns/query.py", line 596, in xfr
    _net_write(s, tcpmsg, expiration)
  File "/usr/lib/python3/dist-packages/dns/query.py", line 364, in _net_write
    current += sock.send(data[current:])
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/kali/Exercises/Module_7/dns-axfer.py", line 73, in <module>
    zoneXFR()
  File "/home/kali/Exercises/Module_7/dns-axfer.py", line 66, in zoneXFR
    print ("\nResults for",server, "\nZone origin:", str(zone.origin).rstrip('.'))
UnboundLocalError: local variable 'zone' referenced before assignment

我的剧本：抨击...我总是可以接受建设性的批评。 

#!/usr/bin/python3

import sys, argparse
import dns.query
import dns.zone
import dns.resolver
from colorama import Fore, Style

bracket = f"{Fore.BLUE}[{Fore.GREEN}*{Fore.BLUE}]{Style.RESET_ALL} "
bracket_err = f"{Fore.BLUE}[{Fore.RED}*{Fore.BLUE}]{Style.RESET_ALL} "
'''
parser = argparse.ArgumentParser()
parser.add_argument('domain')
args = parser.parse_args()
'''
# domain = (sys.argv[1])
domain = 'megacorpone.com'
#domain = 'zonetransfer.me'

def line():
    print ('-' * 75)
    return None

def resolveDNS(system):
    resolver = dns.resolver.Resolver()
    results = resolver.query(system , "A")
    return results

def getNS ():
    name_servers = dns.resolver.query(domain, 'NS')
    print ("\nThe name servers for " + domain + " are:")
    line()
    for system in name_servers:
        A_records = resolveDNS(str(system))
        for item in A_records:
            answer = ','.join([str(item)])
        print (bracket, "{:30}".format(str(system).rstrip('.')), "{:15}".format(answer))
    return name_servers

def getMX():
    mail_server = dns.resolver.query(domain, 'MX')
    print("\nMail servers for", domain)
    line()    
    for system in mail_server:
        A_records = resolveDNS(str(system.exchange))
        for item in A_records:
            answer = ','.join([str(item)])          
        print(bracket, "{:30}".format(str(system.exchange).rstrip('.')), "{:15}".format(str(answer)), '\t', "{:5}".format("Preference:"), str(system.preference))
    return None

def zoneXFR():
    print ("\nAttempting zone transfers for", domain,)

    for server in name_servers:
        try:
            zone = dns.zone.from_xfr(dns.query.xfr(str(server).rstrip('.'), domain))
            print ("\nResults for",server, "\nZone origin:", str(zone.origin).rstrip('.'))
            line()
            for host in zone:
                if str(host) != '@':
                    A_records = resolveDNS(str(host) + "." + domain)
                    for item in A_records:
                        answer = ','.join([str(item)])   
                    print(bracket, "{:30}".format(str(host) + "." + domain), answer)
        except Exception as e:
            print ("\nResults for",server, "\nZone origin:", str(zone.origin).rstrip('.'))
            line()
            print (bracket_err, f"{Fore.RED}Error:{Style.RESET_ALL}", e.__class__, e)


name_servers = getNS()
getMX()
zoneXFR()
print("\n")
4

2 回答 2

3

我看到您正在尝试专门为测试而设置的知名名称服务器。但是，为了其他读者的利益，我将添加一些解释。

您可能知道，现在大多数名称服务器都不允许区域传输。话虽如此，给定域名的每个名称服务器可能会表现不同（它们可能具有不同的配置，甚至运行不同的软件）。

在 megacorpone.com 的情况下，列出了 3 个名称服务器：

  • ns2.megacorpone.com。
  • ns3.megacorpone.com。
  • ns1.megacorpone.com。

ns2.megacorpone.com 是唯一允许区域转移的网站。

这条信息

dns.query.TransferError: Zone transfer error: REFUSED

意思是什么意思：您的查询被拒绝了。可能您与错误的名称服务器交谈。

然后你有另一个错误提示变量范围问题：

UnboundLocalError: local variable 'zone' referenced before assignment

您按以下顺序调用函数：

name_servers = getNS()
getMX()
zoneXFR()

如果name_servers失败，则后续调用也zoneXFR将失败。因为这段代码：

for server in name_servers:

将尝试遍历一个空列表。

间歇性 DNS 解析失败很常见，因此此处需要进行一些检查。至少，确保 NS 列表不为空。

另一个问题：您for在块外启动一个循环，try因此您的控制结构在中间被破坏：

for server in name_servers:
    try:
        zone = dns.zone.from_xfr(dns.query.xfr(str(server).rstrip('.'), domain))
        print ("\nResults for",server, "\nZone origin:", str(zone.origin).rstrip('.'))
        line()

改为这样做：

try:
    for server in name_servers:
        zone = dns.zone.from_xfr(dns.query.xfr(str(server).rstrip('.'), domain))
        print ("\nResults for",server, "\nZone origin:", str(zone.origin).rstrip('.'))
        ...

我怀疑您的脚本会间歇性地失败，因为名称服务器列表并不总是以相同的顺序返回。如果返回的第一个 NS 是 ns1.megacorpone.com。或 ns3.megacorpone.com。然后代码崩溃。如果脚本以 ns2.megacorpone.com（唯一允许区域传输的 NS）开头，那么它似乎可以正常工作。

当此代码失败时（AXFR 被拒绝）：

zone = dns.zone.from_xfr(dns.query.xfr(str(server).rstrip('.'), domain))

thenzone没有定义，这就是为什么你不能在你的异常块中打印它。相反，请显示您知道已定义且有效的域名或其他一些变量。

因此，如果 AXFR 被拒绝，您的脚本应该处理此异常dns.query.TransferError，并悄悄地转到下一个 NS（如果有），直到列表用完为止。

另一点建议：您尝试解析与“@”不同的资源名称。相反，请查看记录类型。你应该只解决CNAME,MX或NS. 其他常见的类型是TXT, A, AAAA, SOA。其余的则更具异国情调，例如NAPTR,LOC或SRV。我认为没有什么应该解决的。

于 2020-03-21T22:55:49.850 回答
0

修正了你的代码，看起来还不是很好，但它可以工作

#!/usr/bin/python3
# you might want to run python3 -m pip install dnspython before running this script

import sys
import dns.query
import dns.zone
import dns.resolver

# formatting setup
from colorama import Fore, Style
bracket = f"{Fore.BLUE}[{Fore.GREEN}*{Fore.BLUE}]{Style.RESET_ALL} "
bracket_err = f"{Fore.BLUE}[{Fore.RED}*{Fore.BLUE}]{Style.RESET_ALL} "
def drawLine():
    print ('-' * 75)
    
# read arguments    
try:
    domain = (sys.argv[1])
except:
    print("[!] USAGE: python3 zt.py DOMAIN_NAME")
    sys.exit(0)

# DNS functions
def resolveDNS(name):
    resolver = dns.resolver.Resolver()
    results = resolver.query(name , "A")
    return results

def getNS (domain):
    mapping = {}
    name_servers = dns.resolver.query(domain, 'NS')
    print ("\nThe name servers for " + domain + " are:")
    drawLine()
    for name_server in name_servers:
        A_records = resolveDNS(str(name_server))
        for item in A_records:
            answer = ','.join([str(item)])
        mapping[str(name_server)] = answer
        print (bracket, "{:30}".format(str(name_server).rstrip('.')), "{:15}".format(answer))       
    return mapping
    
def zoneXFR(server):
    try:
        zone = dns.zone.from_xfr(dns.query.xfr(str(server).rstrip('.'), domain))
    except Exception as e:
        print (bracket_err, f"{Fore.RED}Error:{Style.RESET_ALL}", e.__class__, e)
    else:
        print ("\nResults for",server, "\nZone origin:", str(zone.origin).rstrip('.'))
        drawLine()
        for host in zone:
            if str(host) != '@':
                A_records = resolveDNS(str(host) + "." + domain)
                for item in A_records:
                    answer = ','.join([str(item)])   
                print(bracket, "{:30}".format(str(host) + "." + domain), answer)
        drawLine()
        
name_servers = getNS(domain)
for server in name_servers:
    print ("\nAttempting zone transfers for", server,name_servers[server])
    zoneXFR(name_servers[server])
于 2020-08-25T16:51:30.747 回答