localhost name lookup

[Peter 'PMc' Much]

On Tue, Jan 14, 2025 at 10:47:35PM +0100, Emmanuel Fusté wrote:

! localhost is defined as a (local) hostname of the loopback interface, not a
! domain name.

Where would that be defined? Because, what You state is a
contradiction in itself: a hostname is a designation of the metal
(or virtual, nowadays), it has nothing to do with interfaces
(An interface cannot possess the host, just like a door cannot
possess the room),

Considering the hostname eqivalent to an address label on an
interface (no matter if that might be stored in DNS or elsewhere) is a
common misunderstanding by people who do not know that more than one
interface card can be installed in a machine, neither that ip
aliases do exist.

The result of this misunderstanding is what makes Kerberos
configuration a venture into hell - because the designers insisted
that a hostname and an address label are the same and therefore
that there can be only one address for a host.
The only sensible way to cope with such designs is then to give them
localhost as their desired domain name (that one is always valid):

root at edge:~ # ktutil list
Vno  Type                     Principal                     Aliases
  1  aes256-cts-hmac-sha1-96  host/localhost at INTRA.PHASE23  

This works as long as one doesn't allow Kerberos from [ab]using DNS
for storage. It might even work with DNS when implementing subdomains
under "localhost" in an appropriate way.

Have fun,
PMc