[Tutor] Socket Module

[Nym City]

Thank you all for your responses. I have taken your feedback and made changes to my code.
-Danny, per your suggestion, I have renamed some of my variables to make their purpose little more clearer.
- Alan,  I have created a new host list (ResolvedAddresses) which is storing the output from socket.gethostbyaddr(address).

Here is the updated code: https://bpaste.net/show/358583e1a0bd
The issue that I am running into now is that for some reason, the script is not resolving known-public IP addresses that I am passing through. For example, some of the IPs, that I have used are for sites like facebook (173.252.120.6) github (207.97.227.239), however the script is not able to resolve them.
But its interesting that I am able to resolve them using nslookup on windows command prompt. 
Which means my laptop's DNS setting is fine.
Looking forward to your feedback. Thanks!

 Thank you. 


     On Monday, July 20, 2015 5:00 AM, Alan Gauld <alan.gauld at btinternet.com> wrote:
   
 

 On 20/07/15 00:55, Nym City via Tutor wrote:
> Thank you for your response. I gave it another try:
> As suggested, first I ran the concept just in the terminal, and it worked fine:
>>>> names =['173.252.120.6', '98.139.183.24']
>>>> import socket
>>>> for name in names:
>      socket.gethostbyaddr(name)
>      print(name)
>
> output:
> ('edge-star-shv-12-frc3.facebook.com', [], ['173.252.120.6'])
> ('ir2.fp.vip.bf1.yahoo.com', [], ['98.139.183.24'])

Remember that the >>> prompt evaluates your results and
automatically prints them for you.

Thus

 >>> 5 + 3
8

But if you put code in a script and execute it the interpreter
does NOT print out arbitrary expressions so a file add.py
containing just

5 + 3

will not output anything, you need the print function:

print(5+3)

to see the result.

So in the interpreter your gethostbyaddr() function is
evaluated AND printed. But in a script it will only be
evaluated...

> import csv
> import socket
>
> domains = []
>
> with open('top500ips.csv', 'r') as f:
>      for line in f:
>          line = line.strip()
>          domains.append(line)

You are importing csv but not using it to read your file.
But I'll ignore that for now! (in fact it looks like the
csv file really only contains the IP addresses, one per
line so csv is probably redundant here.)

Also you could do all of the above in a single line with:

domains = [line.strip() for line in open('top500ips.csv')]

But none of that matters for your specific issue...

> for name in domains:
>      socket.gethostbyaddr(name)
>      print(name)

Notice here that you run the gethostbyaddr() function but
do nothing with the result. You don't store it and you
don't print it. Instead you print the initial name that
you passed in, which does not change.

You need to create a variable to store the host result
and then print that host. And since you want to store a
set of hosts you probably want to append the results to
a list of some kind (or a dictionary based on your names?)

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos


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