How to find IP Addresses

[Michael Tibor]

On Mon, 27 Jul 1998 Beth DeGeer <bdeg at bartlesville.lib.ok.us> wrote:

> This is probably a really stupid question,  but I hope you will indulge
> me.  I have two public access computers on which patrons can play games,
> email and chat.  The other eight are limited to research only.  Let's
> say I wanted to block access to hotmail.com on the 8 research-only
> computers.  How can I find the  IP address of hotmail.com?  Is this
> something I can find with a whois search at internic's site?  Thanks for
> your help.
> 
> Beth DeGeer
> Bartlesville Public Library

The best way to implement this kind of filtering is done in a proxy. 
That way you have centralized administration of it-- no running around
to each machine to add a new domain or IP address to block (you may
think it won't be a problem with the relatively few machines you have
now, but trust me when I say that the blocking method you choose now
will probably be the one you have to deal with as you put out more and
more public machines). 

We're using Squid (http://squid.nlanr.net/) on a Linux server and have
had great results.  Both are basically free, although we've stayed
with this setup primarily because it's more flexible than most
commercial web proxies.

As for the other part of your question (how to find out IP addresses
from hostnames, and which IP blocks and domains belong to who), you
can do all of this over the web:

1.  To find out who the 'hotmail.com' domain belongs to (contact info
    and such), go to http://rs.internic.net/ and use their online
    whois search.

2.  To find out which IP address(s) are associated with 'hotmail.com'
    go to http://www.orionsys.com/cgi-bin/nslookup.cgi  (they don't
    use a 'submit' button on their form, so some browsers may not 
    work).

3.  To find out what IP blocks have been issued to 'hotmail.com' go to
    http://www.arin.net/whois/arinwhois.html


Hope that helps,
Mike
-- 
Mike Tibor         Univ. of Alaska Anchorage    (907) 786-1001 voice
LAN Technician     Consortium Library             (907) 786-6050 fax
tibor at lib.uaa.alaska.edu       http://www.lib.uaa.alaska.edu/~tibor/
Finger tibor at asimov.lib.uaa.alaska.edu for PGP public key