Whois 172/12

Ted Fischer ted at fred.net
Sun Jan 15 02:20:17 CST 2012


Thanks for the replies so far, but not what I was looking for.

I should have specified that I've done several ns & dig lookups just to
make sure.

We were supposed to have lit up the last of IPv4 last year.  I would have
presumed that meant that there was nothing left.  Since I can't find a
reference to 172/12 anywhere, one might be led to presume that it was
allocated somehow, to someone (perhaps inadvertently not recorded) since
there are - supposedly - no fresh IPv4 addresses left to allocate, and the
only reference to this block is that 172/8 is allocated to ARIN.  It
doesn't even appear in RFC 5735.

We all know about 172.16/12 - nothing left of that horse but glue.

My question is about 172/12.  Where is it, what is it's supposed purpose. 
I'm almost sure it's an internal box.  I just find it better to give a
professional answer to "why can't I use this" than just "you can't use
this and why is this address scanning you for udp/137 anyway".

If someone can point out to me what was done with 172/12 I'd appreciate it.


Patrick opined:
> Read RFC1918.

  I didn't remember seeing anything about 172/12 in RFC1918.  Looked at it
again.  Is there something about 172/12 I missed?  Thanks.

> Likely a machine on his local network (i.e. behind the same NAT box) is
> hitting him.
>
> But that is not guaranteed.  A packet with a source address of 172.0.x.x
> could be hitting his machine.  Depends on how well you filter.  Many
> networks only look at destination IP address, source can be anything -
> spoofed, un-NAT'ed, etc.  He just wouldn't be able to send anything back
> to it (unless it was on the local LAN, as I mention above).
>
> --
> TTFN,
> patrick
>
>
> On Jan 15, 2012, at 2:53 AM, Alex Ryu wrote:
>
>> As far as I know, 172.0.1.216 is not assigned, yet.
>>
>> whois -h whois.arin.net 172.0.1.216
>> [whois.arin.net]
>> #
>> # Query terms are ambiguous.  The query is assumed to be:
>> #     "n 172.0.1.216"
>> #
>> # Use "?" to get help.
>> #
>>
>> No match found for 172.0.1.216.
>>
>>
>>
>> #
>> # ARIN WHOIS data and services are subject to the Terms of Use
>> # available at: https://www.arin.net/whois_tou.html
>> #
>>
>> Also, when you check BGP routing table, it is not routed at all.
>>
>> route-server.as3257.net>sh ip bgp 172.0.1.216
>> % Network not in table
>> route-server.as3257.net>
>>
>> So it seems like forged IP address.
>>
>> Alex
>>
>>
>> On Sun, Jan 15, 2012 at 1:37 AM, Ted Fischer <ted at fred.net> wrote:
>>> Hi all,
>>>
>>>   Tearing what's left of my hair out.
>>>
>>>   A customer is getting scanned by a host claiming to be "172.0.1.216".
>>>
>>>   I know this is bogus, but I want to go back to the customer with as
>>> much authoritative umph as I can (heaven forbid they just take my
>>> word).
>>>
>>>   I'm pretty sure I read somewhere once that 172/12 was "reserved" or
>>> something like that.  All I can find now is that 172/8 is "administered
>>> by
>>> ARIN".  Lots of information on 172.16/12, but not a peep about
>>> 172/12.
>>>
>>>   If anybody could provide some insight as to the
>>> allocation/non-allocation of this block, it would be much appreciated.
>>>
>>>   Thanks.
>>>
>>> Ted Fischer
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>
>
>





More information about the NANOG mailing list