[NTLUG:Discuss] internet routing of private IPs causing problems..

[Richard Geoffrion]

Am I misunderstanding something about RFC1918 ( 
http://www.rfc-archive.org/getrfc.php?rfc=1918 )?  It is my 
understanding that RFC1918 dictates that the private ip address ranges...

     10.0.0.0        -   10.255.255.255  (10/8 prefix)
     172.16.0.0      -   172.31.255.255  (172.16/12 prefix)
     192.168.0.0     -   192.168.255.255 (192.168/16 prefix)

...are to be filtered out from routers from routers that are on the 
internet (ie ISP routers)?  Quote:

  "Routers in networks not using private address space, especially
   those of Internet service providers, are expected to be configured
   to reject (filter out) routing information about private networks."

That SEEMS pretty clear cut to me and in all my years of networking has 
been the standard.  Now I'm being told by a (supposedly) major 
DATA/TELCOM company that it is the responsibility of the customer 
premise equipment performing NAT to filter outbound  requests to IP 
address in the specified private address range.

I am frustrated and a bit upset at what I am perceiving as either 
ignorance, stupidity, or blatant uncaring on the part of a seemingly 
lazy ISP.  It makes it kind of hard to monitor online status of an 
internal device when an outside device at the ISP responds to a ping to 
a private IP address.

Do I have the high-ground here or does the ISP have any shred of 
evidence on which to stand?

(I do see in the RFC where it is recommended that... "an enterprise 
should also filter any private networks from inbound routing information 
in order to protect itself from ambiguous routing situations which can 
occur if routes to the private address space point outside the 
enterprise."    I'll need to see how to implement that without screwing 
up my routing tables.)

-- 
Richard