Re: Bogon ASN Filter Policy

[Jay Borkenhagen <jayb () braeburn org>]

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...


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