Re: someone is using my AS number

[Warren Kumari <warren () kumari net>]

On Thu, Jun 13, 2019 at 9:59 AM Joe Abley <jabley () hopcount ca> wrote:
> Hey Joe,
>
> On 12 Jun 2019, at 12:37, Joe Provo <nanog-post () rsuc gweep net> wrote:
>
> > On Wed, Jun 12, 2019 at 04:10:00PM +0000, David Guo via NANOG wrote:
> > > Send abuse complaint to the upstreams
> >
> > ...and then name & shame publicly. AS-path forgery "for TE" was
> > never a good idea. Sharing the affected prefix[es]/path[s] would
> > be good.
>
> I realise lots of people dislike AS_PATH stuffing with other peoples' AS numbers and treat it as a form of hijacking.

Actually, I've been meaning to start a thread on this for a while.

I have an anycast prefix - at one location I'm a customer of a
customer of ISP_X &  ISP_Y & ISP_Z. Because ISP_X prefers customer
routes, any time a packet touches ISP_X, it goes to this location,
even though it is (severely) suboptimal -- things would be better if
ISP_X didn't accept this route in this location.

Now, the obvious answer of "well, just ask your provider in this
location to not announce it to ISP_X. That's what communities / the
telephone were invented for!" doesn't work for various (entirely
non-technical) reasons...

Other than doing path-poisoning can anyone think of a way to
accomplish what I want? (modulo the "just become a direct customer
instead of being a customer of a customer" or "disable that site", or
"convince the AS upstream of you to deploy communities / filters").
While icky, sometimes stuffing other people's AS in the path seems to
be the only solution...

W


> However, there's an argument that AS_PATH is really just a loop-avoidance mechanism, not some kind of AS-granular 
> traceroute for prefix propagation. In that sense, stuffing 9327 into a prefix as a mechanism to stop that prefix 
> being accepted by AS 9327 seems almost reasonable. (I assume this is the kind of TE you are talking about.)
>
> What is the principal harm of doing this? Honest question. I'm not advocating for anything, just curious.
>
>
> Joe


-- 
I don't think the execution is relevant when it was obviously a bad
idea in the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair
of pants.
   ---maf