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comp.lang.python

problem with gethostbyaddr with intranet addresses on MAC

shailesh

1/25/2008 11:12:00 AM

Hi,

I am facing a peculiar problem. socket.gethostbyaddr is not working
fine on my MAC for ip addresses on the LAN. The LAN happens to consist
of linux and windows machines and this is the only one MAC on the
LAN.

Please see the example below. I am getting error: socket.herror: (1,
'Unknown host')



apples-computer:~ apple$ ping 192.168.4.123
PING 192.168.4.123 (192.168.4.123): 56 data bytes
64 bytes from 192.168.4.123: icmp_seq=0 ttl=64 time=0.328 ms
64 bytes from 192.168.4.123: icmp_seq=1 ttl=64 time=0.236 ms
64 bytes from 192.168.4.123: icmp_seq=2 ttl=64 time=0.255 ms
^C
--- 192.168.4.123 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.236/0.273/0.328/0.040 ms
apples-computer:~ apple$ python2.4
Python 2.4.4 (#1, Oct 18 2006, 10:34:39)
[GCC 4.0.1 (Apple Computer, Inc. build 5341)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from socket import *
>>> x = gethostbyname('google.com')
>>> x
'64.233.167.99'
>>> gethostbyaddr(x)
('py-in-f99.google.com', [], ['64.233.167.99'])
>>> e = '192.168.4.123'
>>> gethostbyaddr(e)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
socket.herror: (1, 'Unknown host')
>>>


With regards,
- Shailesh
1 Answer

Sion Arrowsmith

1/28/2008 6:03:00 PM

0

shailesh <shaileshk@gmail.com> wrote:
>Python 2.4.4 (#1, Oct 18 2006, 10:34:39)
>[GCC 4.0.1 (Apple Computer, Inc. build 5341)] on darwin
>Type "help", "copyright", "credits" or "license" for more information.
>>>> from socket import *
>>>> x = gethostbyname('google.com')
>>>> x
>'64.233.167.99'
>>>> gethostbyaddr(x)
>('py-in-f99.google.com', [], ['64.233.167.99'])
>>>> e = '192.168.4.123'
>>>> gethostbyaddr(e)
>Traceback (most recent call last):
> File "<stdin>", line 1, in ?
>socket.herror: (1, 'Unknown host')
>>>>

So what are you expecting it to return? Or, to put it another way,
what would you feed to gethostbyname() to get 192.168.4.123 back?
Can you get the "right" answer from host or some other command-
line tool? Can you get an answer from gethostbyaddr() on one of
the other machines on the network? How do they do their name
resolution?

--
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