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Re: Regarding smaller prefix for hijack protection
From: Suresh Ramasubramanian <ops.lists () gmail com>
Date: Thu, 30 Aug 2012 17:30:27 +0530

You might find your /24 routes filtered out at a lot of places that do
have sensible route filtering

But then yes, it'd protect you against the idiots who dont know bgp
from a hole in the ground anyway and let whatever hijacking happen

But I'd suggest do whatever such announcement if and only if you see a
hijack, as a mitigation measure.

On Thu, Aug 30, 2012 at 5:24 PM, Anurag Bhatia <me () anuragbhatia com> wrote:
Hello everyone!

I tried looking on net but couldn't found direct answer, so thought to ask
here for some advise.

Is using /24 a must to protect (a bit) against route hijacking? We all
remember case of YouTube 2008 and hijacking in Pakistan. At that time
YouTube was using /22 and thus /24 (more specific) announcement took almost
all of Google's traffic even when AS path was long. So Google's direct also
likely sent packets to Pakistan. Later Google too used /24 (and I guess /25
too to effect some region of internet). Similar case I remember for issue
reported between Altus and hijacking by someone connected to Cleaveland
exchange when ISP was using /23 and spammer used /24.

So can we conclude that one should always use /24 to make sure that they
loose as little as possible traffic during prefix hijacking?

Also, if one uses /22 and /24 - will both prefixes will show in Global
routing table? I know /24 will be prefered but will ISP see /22 as well or
it will pop up only when /24 is filtered?

For one of IP's of Google.com, it seems it is coming from /16 and /24


How can one print similar result from a route server like say Oregon route
views or any ISP's server? I always /24 when looking for that IP. (in
simple words - how bgp.he.net does this magic of popping both prefixes? I
failed to do get same result from HE's route server)



Anurag Bhatia

Linkedin <http://in.linkedin.com/in/anuragbhatia21> |
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Suresh Ramasubramanian (ops.lists () gmail com)

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