Announcing a reserved ASN?

Brandon Ross bross at pobox.com
Sun Feb 3 16:15:04 UTC 2013


I strongly recommend that you read about and fully understand how 4-byte 
ASNs work, and their use of AS23456 before you continue this thread.

On Sun, 3 Feb 2013, Suresh Ramasubramanian wrote:

> I do believe, as has been pointed out to me elsewhere that this is what
> shows up when there's a 64 bit ASN and router software that doesn't grok 64
> bit ASNs
>
> So, completely by chance that one such as belongs to what looks like a bulk
> mailer
>
> --srs (htc one x)
> On 03-Feb-2013 9:02 PM, "Dave Pooser" <dave.nanog at alfordmedia.com> wrote:
>
>> On 2/3/13 9:04 AM, "Rich Kulawiec" <rsk at gsp.org> wrote:
>>
>>> On Sun, Feb 03, 2013 at 06:12:32PM +0530, Suresh Ramasubramanian wrote:
>>>> AS23456 is currently announcing a good few netblocks (which don't have a
>>>> very good smtp reputation, by the way).
>>>
>>> To say the least.  A quick rDNS scan reveals that those netblocks include:
>>>
>>>       8448  addresses
>>>       6932  return nxdomain
>>>       512   return servfail
>>>       1004  with rDNS entries
>>>
>>> Those 1004 hosts with rDNS account for 36 domains:
>>
>> <snip long list of spammy domains>
>>
>> Just as another data point, the domain names you listed hit on enough URL
>> blacklists that Spamassassin quarantined the message for me (and would
>> have rejected it during the SMTP transaction had the NANOG server not been
>> listed on DNSWL-High). Spam hosts plus fake ASN = paging the Spamhaus DROP
>> maintainers to the white courtesy phone....
>> --
>> Dave Pooser
>> Manager of Information Services
>> Alford Media  http://www.alfordmedia.com
>>
>>
>>
>>
>

-- 
Brandon Ross                                      Yahoo & AIM:  BrandonNRoss
+1-404-635-6667                                                ICQ:  2269442
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