Re: [gentoo-user] Why do we add the local host name to the 127.0.0.1 / ::1 entry in the /etc/hosts file?

[Mark Knecht <markknecht@gmail.com>]

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On Wed, Mar 10, 2021 at 9:44 AM Grant Taylor <
gtaylor@gentoo.tnetconsulting.net> wrote:
>
> On 3/10/21 6:27 AM, Mark Knecht wrote:
> > Caveat - not an expert, just my meager understanding:
> >
> > 1) The name 'localhost' is historically for developers who want to
> > access their own machine _without_ using DNS.
>
> Eh....
>
> Using the /name/ "localhost" still uses name resolution.  It could use
> DNS or it may not.  It /typically/ means the /etc/hosts file.  But it
> could mean DNS or NIS(+) or LDAP or something more esoteric.
>

OK, agreed, completely. localhost must be turned into an IP address.

I guess what I was thinking was DNS means Server. If it's a Service
then that's different. I think we're in agreement that if it can find the
name in /etc/hosts, either actively or cached somewhere in memory,
then it doesn't have to send anything over a cable to get the answer.

And cable is too generic as I understand that DNS might be on this
machine.

Point taken.

> IMHO what's special about the "localhost" name in particular is that
> it's an agnostic / anycast method to say the local host that a given
> program is running on without regard to what the actual host name is.
>

Agreed but I suspect if I don't have it in /etc/hosts then I'm unlikely
to get results that make sense in real time, but that's case buy case.

Again, completely agreed.

> > 2) By general practice sometime in the deep, dark times 127.0.0.1 was
> > accepted for this purpose. There's nothing special about the address.
>
> Deep, dark times?  It's still used every single day across multiple
> platforms, Linux, Unix, Windows, z/OS, i/OS, you name it.
>

<LOL> I'm approaching my 66th birthday. Deep dark times for me are
almost certainly more recent dates than for you. ;-)

> > 3) I read the original quoted comment in the Kerberos Guide as a warning
> > - 'to make matters worse, __SOME__"
>
> What did the warning mean to you?  Because I took it as "be careful,
> your $OS /may/ do this incorrectly".  Where "this" is putting the FQDN
> on the same line as 127.0.0.1 and / or ::1.
>

I took it as simply a Kerberos setup/config warning. Whoever wrote that
had an opinion, experience or both and wanted you to know that. I
didn't read anything more into it. The author cannot change what
"some distros" do but wants to give you a fighting chance to get
Kerberos working in case you're using one. Makes no sense to mention
a specific distro because the list probably changes over time.

Basically "You'd be wise to look at your /etc/hosts file and fix this
silly configuration error that some distros do before trying to
setup Kerberos"

<SNIP>

> I'm grateful for corroboration, but unfortunately that doesn't speak to
> why the Gentoo handbook suggests what it does.

I'm not a sys admin nor a Gentoo developer or documenter so I cannot
comment on the manual specifically.

As I no longer run Gentoo - I haven't for about 3 years other than one
remaining VM seldom used and seldom updated - I'm way out of
touch with the actual manual but interested in the subject.

Over and out.

- Mark

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