How to find all of an ISP's ASNs

Thu Oct 27 21:38:30 UTC 2016

On Tue, Oct 25, 2016 at 9:03 PM, Hank Nussbacher <hank at efes.iucc.ac.il>
wrote:

> and if that doesn't work try:
> http://bgp.he.net/AS3356#_graph4
> [replace the ASN with the ASN of your choice to see the interconnections.]
>

Doesn't always work--as it will only show upstream ASNs.

For example, Comcast's backbone AS interconnects their regional ASNs.
However, the regionals don't show up on http://bgp.he.net/AS7922#_graph4 so
you'd need to find all of them first...with something like
http://bgp.he.net/search?search[search]=Comcast and/or consult your
favorite route server.

Also Gary, keep in mind these aren't static. I.e. new AS are added/removed
over time. And inferred policy (i.e. hub/spoke) could change too.

But I'm still curious...how to you propose to filter by AS?

And what if your neighbor (inside one of those permitted AS) is
compromised? You've just re-exposed your IoT devices' soft white underbelly
again. :-(

../C