202401100645.AYC Re: IPv4 address block

Wed Jan 10 15:45:30 UTC 2024

On 1/10/24 10:12, Tom Beecher wrote:
> Karim-
> 
> Please be cautious about this advice, and understand the full context.
> 
> 240/4 is still classified as RESERVED space. While you would certainly 
> be able to use it on internal networks if your equipment supports it, 
> you cannot use it as publicly routable space. There have been many 
> proposals over the years to reclassify 240/4, but that has not happened, 
> and is unlikely to at any point in the foreseeable future.

While you may be able to get packets from point A to B in a private 
setting, using them might also be .. a challenge.

There's a whole bunch of software out there that makes certain 
assumptions about allowable ranges. That is, they've been compiled with 
a header that defines ..

#define IN_BADCLASS(i)	(((in_addr_t)(i) & 0xf0000000) == 0xf0000000)

	Michael