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