Re: The use of .0/.255 addresses.

[abuse () cabal org uk (Peter Corlett)]

Jonathan McDowell <noodles () earth li> wrote:
[...]
> Various people I've asked about this have said they wouldn't use the
> .0 or .255 addresses themselves, though couldn't present any
> concrete info about why not; my experience above would seem to
> suggest a reason not to use them.

It's funny that it is you of all people that would note this, as I
came to the same sort of conclusion after configuring and installing
tippett.debian.org for you.

Tippett has the IP address of 195.92.249.0. In the old classful
scheme, this would be in a class C network. Energis actually have
195.92/16 and "supernet" the class Cs into more useful chunks. I think
it's a good idea to conserve address space by issuing the IP addresses
thus released.

Unfortunately, a certain software producer in Redmond apparently
hasn't heard of CIDR.

I found that I could ping Tippett from a Windows 2000 box just fine,
but TCP connections would always fail with "connection refused".
Getting a packet sniffer on the job showed that Windows wasn't even
issuing a SYN - it was deciding for itself that a connection wasn't
valid without even trying.

So it seems inadvisable to use addresses that would be network and
broadcast addresses in the old classful scheme. IOW, if you've got,
say, an 80.x.x.x address, .0 and .255 are most likely fine. (But test
it first, as I haven't.)

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