"127.0.0.1" option specified, but still using "localhost" name - mysql

Question

I'm using the -h option, specifying that I want to connect to MySQL Server via a specific host/interface, but MySQL is telling me this, which apparently doesn't make so much sense
root#ilg40:/# mysql -h 127.0.0.1 -u root -proot
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1698 (28000): Access denied for user 'root'#'localhost'
OBS.: I have created a access for root via 127.0.0.1 (FLUSH PRIVILEGES() was already performed.
root#ilg40:/# mysql -e "SELECT User,Host,authentication_string FROM mysql.user;"
+-----------+-----------+-------------------------------------------+
| User | Host | authentication_string |
+-----------+-----------+-------------------------------------------+
| root | localhost | |
| mysql.sys | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| root | 127.0.0.1 | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B |
+-----------+-----------+-------------------------------------------+
Have you guys any idea about what's going on?
I can't find where is my failure :(..
P.S: I'm using Debian Jessy + MySQL 5.7.12
root#ilg40:/# cat /etc/debian_version
8.4
root#ilg40:/# mysql -e "SELECT VERSION();"
+-----------+
| VERSION() |
+-----------+
| 5.7.12 |
+-----------+

Answer 1

Acoording to MySQL official doc:
"The server performs host name resolution using the thread-safe
gethostbyaddr_r() and gethostbyname_r() calls if the operating system
supports them.
Otherwise, the thread performing the lookup locks a mutex
and calls gethostbyaddr() and gethostbyname() instead.
In this case, no other thread can resolve host names that are not in the host
cache until the thread holding the mutex lock releases it."
The solution I found was: dropping the user 'root'#'localhost' from MySQL.
DROP USER 'root'#'localhost';
I tried to modify the /etc/hosts, but no good. There's something else around the way that MySQL performs these two syscalls, which maps 127.0.0.1 to localhost, independently if you the address mapped in a different way in /etc/hosts.
WARNING: be sure to have at least another user with admin powers on MySQL, using 127.0.0.1 for connection, or else, you may loose access and/or admin powers over MySQL.