I'm not against the theory of what is being proposed, but I was surprised to see little discussion of this announcement on list. Upon examination on my view of the DFZ from AS3128 I see over 400 upstream routes falling into this category, mostly in the 64512 - 65534 range. Based on our flow bandwidth stats we chose to reach out to several origin ASN, two fairly well known, as a courtesy. For the *TT's who are planning on implementing shortly, have you went through a similar diagnostic effort and what might you share or report on such endeavors? -Michael
-----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Arnold Nipper Sent: Wednesday, June 08, 2016 12:37 AM To: Jay Borkenhagen <jayb@att.com>; nanog@nanog.org Subject: Re: Bogon ASN Filter Policy
On 03.06.2016 15:08, Jay Borkenhagen wrote:
AT&T/as7018 is also now in the process of updating its as-path bogon filters to match those cited below. We have long employed such filters, and our changes at this time are primarily to extend them to prohibit as23456 and the reserved blocks > as65535.
So to Job and Adam and anyone else who deploys such filters: Thanks! I would like to extend to you this laurel, and hearty handshake...
Well done, NTT, GTT, AT&T. You may want to notice that most of the IXP around the world which operate route servers since long do strict filtering. Both on ASN as well as on prefixes. So it's really nice to see, that the big ISP take care as well now.
As I have learnt yesterday at ENOG11 a way more challenging issue is to cope with route leaks.
Cheers and cu in chi Arnold
On 02-June-2016, Adam Davenport writes:
I personally applaud this effort as initiatives like this that help prevent the global propagation of Bogons and other "bad things" only serves to help us all. With that said, notice went out to potentially affected GTT / AS3257 customers this week that by the end of June we too will be filtering prefixes that contain any of the Bogon ASNs listed below in the in the as-path. I highly encourage other networks to follow suit, as again it only helps us all.
Thanks Job for kicking this one off, and I look forward to others to doing the same!
Adam Davenport / adam.davenport@gtt.net
On 6/2/16 3:41 PM, Job Snijders wrote:
Dear fellow network operators,
In July 2016, NTT Communications' Global IP Network AS2914 will deploy
a
new routing policy to block Bogon ASNs from its view of the default-free zone. This notification is provided as a courtesy to the network community at large.
After the Bogon ASN filter policy has been deployed, AS 2914 will not accept route announcements from any eBGP neighbor which contains a Bogon ASN anywhere in the AS_PATH or its atomic aggregate attribute.
The reasoning behind this policy is twofold:
- Private or Reserved ASNs have no place in the public DFZ. Barring these from the DFZ helps improve accountability and dampen accidental exposure of internal routing artifacts.
- All AS2914 devices support 4-byte ASNs. Any occurrence of "23456" in the DFZ is a either a misconfiguration or software issue.
We are undertaking this effort to improve the quality of routing data as part of the global ecosystem. This should improve the security posture and provide additional certainty [1] to those undertaking network troubleshooting.
Bogon ASNs are currently defined as following:
0 # Reserved RFC7607 23456 # AS_TRANS RFC6793 64496-64511 # Reserved for use in docs and code RFC5398 64512-65534 # Reserved for Private Use RFC6996 65535 # Reserved RFC7300 65536-65551 # Reserved for use in docs and code RFC5398 65552-131071 # Reserved 4200000000-4294967294 # Reserved for Private Use RFC6996 4294967295 # Reserved RFC7300
A current overview of what are considered Bogon ASNs is maintained at NTT's Routing Policies page [2]. The IANA Autonomous System Number Registry [3] is closely tracked and the NTT Bogon ASN definitions are updated accordingly.
We encourage network operators to consider deploying similar policies. Configuration examples for various platforms can be found here [4].
NTT staff is monitoring current occurrences of Bogon ASNs in the routing system and reaching out to impacted parties on a weekly basis.
Kind regards,
Job
Contact persons:
Job Snijders <job@ntt.net>, Jared Mauch <jmauch@us.ntt.net>, NTT Communications NOC <noc@ntt.net>
References: [1]: https://tools.ietf.org/html/draft-thomson-postel-was-wrong-00 [2]: http://www.us.ntt.net/support/policy/routing.cfm#bogon [3]: https://www.iana.org/assignments/as-numbers/as-numbers.xhtml [4]: http://as2914.net/bogon_asns/configuration_examples.txt
-- Arnold Nipper / nIPper consulting, Sandhausen, Germany email: arnold@nipper.de phone: +49 6224 5593407 2 mobile: +49 172 2650958 fax: +49 6224 5593407 9