BGP Hijacking. Fully peered network A accepts routes from its peers based on prefix allocation to AS maps. Network B, which is either pathological (criminal, or bent on censorship) or lacking clue, propagates /24 subnet of Network C's CIDR (Pakistan/YouTube anyone). If network A accepts Network B's announcement, then connectivity from network A to the /24 announced by Network B (which isn't really connected to network B) is either lost, or worse, hijacked.
-----Original Message----- From: Nathan Ward [mailto:nanog@daork.net] Sent: Monday, December 22, 2008 5:45 PM To: nanog list Subject: Re: What is the most standard subnet length on internet
On 23/12/2008, at 2:39 PM, Joe Provo wrote:
On Tue, Dec 23, 2008 at 02:34:39PM +1300, Nathan Ward wrote: [snip]
Let me rephrase; Are there people who are filtering /24s received from eBGP peers who do not have a default route?
of course.
Curiously, it was really meant as a rhetorical question where the answer was "no".
Why are people doing this? Are they lacking clue, or, is there some reasonable purpose?
-- Nathan Ward