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Re: A regression bug comparing Stretch to Jessie -was [Re: Doing a clean install with ATYPICAL constraints]



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On Fri, May 12, 2017 at 02:46:13PM -0500, Richard Owlett wrote:
> On 05/12/2017 12:40 PM, deloptes wrote:

[...]

> >It took me a while to realize there is difference from MySQL perspective if
> >you use localhost and 127.0.0.1. "localhost" goes via unix socket.
> 
> en englais s'il vous plait ;<
> I don't spell well den Anglais ou Francais <lol>

Eh bien, comment vous voulez.

127.0.0.1 is, you probably know that, the Internet (IPV4, to be more
precise) version of "me". On the network, every host sees itself
(among possibly other things) as 127.0.0.1.

A UNIX socket (or unix domain socket) is an entry in the file system
which behaves roughly like a network connection. Two processes can
talk bidirectionally over it, as they might do over a TCP connection.

The database server can listen to local clients over 127.0.0.1
(typically on the regular MySQL port) or over a UNIX domain socket.
There is one subtle difference between both: whereas any process
can talk to 127.0.0.1, you can restrict those who can access the
UNIX domain socket (plus it has a couple of other tricks up its
sleeve).

Thus, when setting up permissions on MySQL, you include the
way the connection has come to the server and it makes sense
to have a different set of permissions depending on whether
things came via a UNIX domain socket (which MySQL calls then
"localhost") or via 127.0.0.1/MySQL port. A bit counterintuitive,
because usually one considers 127.0.0.1 and localhost as
synonyms.

C'est mieux?

Regards
- -- t
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