[MySQL]ERROR 2049エラーが出たときすべきこと “authentication protocol refused (client option ‘secure_auth’ enabled)”エラー

$ mysql -u root -h localhost -p
Enter password:
ERROR 2049 (HY000): Connection using old (pre-4.1.1) authentication protocol refused 
(client option 'secure_auth' enabled)

$ mysql -u root -h localhost -p --skip-secure-auth
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 76561232
Server version: 5.1.72-community-log MySQL Community Server (GPL)
 
Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
 
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
 
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
 
mysql>

--secure-auth
Do not send passwords to the server in old (pre-4.1) format.
This prevents connections except for servers that use the newer password format.
 
As of MySQL 5.7.5, this option is deprecated and will be removed in a future MySQL release. 
It is always enabled and attempting to disable it 
(--skip-secure-auth, --secure-auth=0) produces an error. 
Before MySQL 5.7.5, this option is enabled by default but can be disabled.
 
Note
Passwords that use the pre-4.1 hashing method are less secure than passwords that 
use the native password hashing method and should be avoided. 
 
Pre-4.1 passwords are deprecated and support for them is removed in MySQL 5.7.5.
For account upgrade instructions, see Section 7.5.1.3, 
“Migrating Away from Pre-4.1 Password Hashing and the mysql_old_password Plugin”.

[mysqld]
skip-secure-auth