使用Python的socket.gethostbyaddr（）困难

小编典典

使用Python的socket.gethostbyaddr（）困难

python

我正在尝试使用python中的socket.gethostbyaddr（）来反转IP地址的dns列表，这将为某些值返回“未知主机”，但对于相同的ip使用dig将返回主机名。另外，dig似乎比使用python模块要快得多，这是否有任何特定原因？

import socket

# This returns 'Unknown Host' 
name, alias, addresslist = socket.gethostbyaddr('114.143.51.197')

阅读 223

2021-01-20

共1个答案

小编典典

抱歉，您误会了。114.143.51.197没有PTR记录…因此socket.gethostbyaddr()应该引发错误…您当然需要try/except子句，用于socket.herror

>>> def lookup(addr):
...     try:
...         return socket.gethostbyaddr(addr)
...     except socket.herror:
...         return None, None, None
...
>>> name,alias,addresslist = lookup('4.2.2.2')
>>> print name
vnsc-bak.sys.gtei.net
>>> name,alias,addresslist = lookup('114.143.51.197')
>>> print name
None
>>>

DNS反向查找114.143.51.197 …请注意，它没有有效的PTR记录

[mpenning@Bucksnort ~]$ dig @8.8.8.8 -x 114.143.51.197

; <<>> DiG 9.6-ESV-R4 <<>> @8.8.8.8 -x 114.143.51.197
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 4735
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;197.51.143.114.in-addr.arpa.   IN      PTR

;; AUTHORITY SECTION:
114.in-addr.arpa.       1800    IN      SOA     ns1.apnic.net. read-txt-record-of-zone-first-dns-admin.apnic.net. 17812 7200 1800 604800 172800

;; Query time: 182 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Tue Nov 22 05:11:36 2011
;; MSG SIZE  rcvd: 134

[mpenning@Bucksnort ~]$ python
Python 2.5.2 (r252:60911, Jan 24 2010, 14:53:14)
[GCC 4.3.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import socket
>>> socket.gethostbyaddr('114.143.51.197')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
socket.herror: (1, 'Unknown host')
>>>

这就是有效PTR记录的样子……

[mpenning@Bucksnort ~]$ dig -x 4.2.2.2

; <<>> DiG 9.6-ESV-R4 <<>> -x 4.2.2.2
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61856
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 1

;; QUESTION SECTION:
;2.2.2.4.in-addr.arpa.          IN      PTR

;; ANSWER SECTION:
2.2.2.4.in-addr.arpa.   86400   IN      PTR     vnsc-bak.sys.gtei.net.

;; AUTHORITY SECTION:
2.4.in-addr.arpa.       86400   IN      NS      dnsauth2.sys.gtei.net.
2.4.in-addr.arpa.       86400   IN      NS      dnsauth1.sys.gtei.net.
2.4.in-addr.arpa.       86400   IN      NS      dnsauth3.sys.gtei.net.

;; ADDITIONAL SECTION:
dnsauth1.sys.gtei.net.  1800    IN      A       4.2.49.2

;; Query time: 308 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Tue Nov 22 05:10:16 2011
;; MSG SIZE  rcvd: 158

[mpenning@Bucksnort ~]$ python
Python 2.5.2 (r252:60911, Jan 24 2010, 14:53:14)
[GCC 4.3.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import socket
>>> socket.gethostbyaddr('4.2.2.2')
('vnsc-bak.sys.gtei.net', [], ['4.2.2.2'])
>>>

2021-01-20