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Re: Spoofing ASNs (Re: SNMP DDoS: the vulnerability you might not know you have)
From: Blake Dunlap <ikiris () gmail com>
Date: Thu, 8 Aug 2013 12:46:10 -0500

I noticed that two of my ASNs are on that list for example with low
numbers. I can't fathom how as at least one of them has uRPF implemented on
any actual interfaces and no downstreams/peers.

-Blake

On Thu, Aug 8, 2013 at 12:40 PM, Matthew Petach <mpetach () netflight com>wrote:

On Thu, Aug 8, 2013 at 10:29 AM, Jared Mauch <jared () puck nether net>
wrote:


On Aug 1, 2013, at 2:31 AM, Saku Ytti <saku () ytti fi> wrote:

On (2013-07-31 17:07 -0700), bottiger wrote:

But realistically those 2 problems are not going to be solved any time
in the next decade. I have tested 7 large hosting networks only one of
them had BCP38.

I wonder if it's truly that unrealistic. If we target access networks,
it
seems impractical target.

We have about 40k origin only ASNs and about 7k ASNs which offer
transit,
who could arguably trivially ACL those 40k peers.

If we truly tried, as a community to make deploying these ACLs easy and
actively reach out those 7k ASNs and offer help, would it be
unrealistic
to
have ACL deployed to sufficiently large portion of networks to make
spoofing impractical/expensive?

The following is a sorted list from worst to best of networks that allow
spoofing: (cutoff here is 25k)

(full list -
http://openresolverproject.org/full-spoofer-asn-list-201307.txt )



Count   ASN#
------------
1323950 3462
1300938 4134
1270046 8151
1213972 9737

...

For the technically clueless among us...

what does "count" refer to in this output?
How many times you were able to spoof
an address through them?  How many
different addresses you could spoof through
them?  How many spoofed packets made it
through before being blocked?

It's kinda hard to know what the list
represents without a bit of explanation
around it.  ^_^;

Thanks!  :)

Matt



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