[Collisions] "controlled interruption" - 127/8 versus RFC1918 space

[Rubens Kuhl]

Em 09/01/2014, à(s) 22:25, David Conrad <drc at virtualized.org> escreveu:

> Joe,
> 
> On Jan 9, 2014, at 1:20 PM, Joe Abley <jabley at hopcount.ca> wrote:
>>> To an engineer, 127.0.53.53 is unusual enough to alert them as well as not send them chasing down non-problems.
>> A correct host implementation will not send datagrams to the network with a source or destination address within 127/8 [RFC1700] or ::1/128 [RFC 4291].
> 
> Yep. 
> 
>> However, it's not obvious what implementations do in real life. RFC3330 comments that the IPv4 loopback address is "ordinarily implemented using only 127.0.0.1/32", for example.
> 
> I'm told Linux implements loopback as 127/8, but don't have one handy to test myself.
> MacOSX appears to time out going to anything in 127/8 other than 127.0.0.1
> FreeBSD 8.2 and 9.1 says "sendto: can't assign requested address”

Windows hosts also use 127/8. Also of notice would handling by popular routers, to asses if the host OS ends up sending the packet, what the router would do with that packet. 

Rubens