On Sun, Oct 28, 2018 at 12:04:54PM -0400, Gene Heskett wrote:
On Sunday 28 October 2018 08:43:33 Reco wrote:Hi. On Sun, Oct 28, 2018 at 07:04:02AM -0400, Gene Heskett wrote: > > Ever consider you're doing it the wrong way? > > This will work: > > > > iface eth0 inet static > > address 192.168.NN.12 > > netmask 24 > > gateway 192.168.NN.1 > > in 20 years, I have never seen that syntax used. What man page do I > find that format in. interfaces(5), the usual place.I just checked that man page on wheezy, jessie and stretch, and no examples are found using "netmask 24"
All of those indicate in the man page that netmask can either be a dotted quad or a CIDR mask length.
address 192.168.##.##/24 is supposed to be understood as netmask 255.255.255.0, and has worked here forever. And remains in the man 5 interfaces page. And has Just Worked, until now with stretch.
Ironically, a CIDR netmask in the address was not recognized until wheezy, which is hardly forever. Prior to that the netmask was mandatory (and only recognized the dotted quad format).
Also, I haven't ever seen an official definition of "CIDR", so its possible I need tutoring on that. IMO any man page that uses an acronym, needs to include its definition.
Classless Inter-Domain Routing. Since that probably didn't clear anything up, you likely need to do some googling. "CIDR" is probably a better keyword than "Classless Inter-Domain Routing" so this is a good example of a case where the acronym is best understood (and used) without expansion.