[Dnsmasq-discuss] Specific treatment of Class C addresses

[Simon Kelley]

Downsides to this proposed change.

1) Old versions of Windows might break.
2) Newer versions of windows might break - we've not done testing on 
which do and don't.
3) Other platforms which have made the same mistake might break.
4) Dnsmasq installations which unkowningly rely on this behaviour in 
other respects might break.

Upsides to the proposed change.
1) ~1% more available addresses in DHCP pools.
2) A small amount of code which no longer needs maintenance.

It's not clear to me what the balance is here. Opinions, list?

Simon.




On 18/09/2024 18:22, Jan Ceuleers wrote:
> Dear dnsmasq community,
> 
> The changelog for version 2.47 contains the following:
> 
> 	Don't dynamically allocate DHCP addresses which may break
> 	Windows.  Addresses which end in .255 or .0 are broken in
> 	Windows even when using supernetting.
> 	--dhcp-range=192.168.0.1,192.168.1.254,255,255,254.0 means
> 	192.168.0.255 is a valid IP address, but not for Windows.
> 	See Microsoft KB281579. We therefore no longer allocate
> 	these addresses to avoid hard-to-diagnose problems.
> 
> Unless I'm mistaken the listed Microsoft KB applies only to Windows versions that are long since past end of support. Furthermore, CIDR was introduced by the IETF more than 30 years ago.
> 
> I was therefore wondering whether it is time to retire the special treatment of addresses ending in .0 or .255 in Class C address ranges.
> 
> Many thanks, Jan
> 
> 
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