ISP Address Allocation

jlewis at jlewis at
Sun Nov 14 22:08:32 UTC 1999

On Fri, 12 Nov 1999, Patrick Evans wrote:

> > >What is the best and most accurate way to determine an ISP's range of
> > >addresses?  For example, if I wanted to see what AT&T's allocation of IP
> > >addresses are, how would I go about doing this in the most timely manner?
> > >What about for smaller ISPs?
> > 
> >
> >
> > 
> Or, in the event of this side of the pond, you could have a look at
> the list of local IRs on

These places are useful for finding out who "owns" what block of space,
but the original question was more like "how do I found out all the
address space an organization 'owns'?"  I'm not aware of an easy way to do
that other than walking the entire IPv4 space at the appropriate

Another possibility is go to a route server, and play around with show ip
bgp regex...and look up the resulting networks to see who "owns" them.

 Jon Lewis *jlewis at*|  Spammers will be winnuked or 
 System Administrator        |  nestea'd...whatever it takes
 Atlantic Net                |  to get the job done.
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