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 <t...@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 >>> >>> >>> >>> >>> >>> >>> >> > > >
