On Tue, Feb 12, 2019 at 3:06 PM Nick Hilliard <n...@foobar.org> wrote: > > Matthew Walster wrote on 12/02/2019 14:50: > > For initial deployment, this can seem attractive, but remember that one > > of the benefits an ROA gives is specifying the maximum prefix length. > > This means that someone can't hijack a /23 with a /24. > > they can if they forge the source ASN. RPKI helps against misconfigs > rather than intentional hijackings.
Some networks have AS_PATH filters in place that prevent accepting a spoofed ASN behind an EBGP session that is not authorized to announce the spoofed ASN. Secondly, there also is a group of networks that assign the same local preference for all routes received via peering - meaning that the use of a spoofed ASN will make the AS_PATH one hop longer. In other words: everyone should peer directly with the destination networks that matter to them. This is not news of course. :-) I agree some attacks in some cases may still get through, but I've come to think that ASN spoofing is far less of an issue than I originally thought it would be. Kind regards, Job