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?
Thanks!
Ron Fuller, CCDP, CCNP-ATM, CCNP-Security, MCNE, MCP
3X Corporation
rfuller@3x.com
Or, in the event of this side of the pond, you could have a look at
the list of local IRs on www.ripe.net.
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
registries.
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.
RIPE's site has a good stab at that. The local IR page lists every
IR, alphabetically, by country, and lists all allocations for each
one. I know of no equivalent outside RIPE, but it works well enough on
this side of the Atlantic...
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.
For registries using the Merit IRR daemon, one can get the list of
all netblocks an AS has registered using the backend interface documented
in Appendix B of the IRRd manual.
The manual is at http://www.merit.edu/radb/irrd/irrd.pdf
For example, Merit AS 237 would be
$ whois -h whois.radb.net \!gas237