-- Unit mariadb.service has begun starting up.
Apr 18 02:38:25 instance-1 mysqld[12887]: 2021-04-18  2:38:25 0 [Note] /usr/sbin/mysqld (mysqld 10.4.18-MariaDB-log) starting as process 12887 ...
Apr 18 02:38:25 instance-1 mysqld[12887]: 2021-04-18  2:38:25 0 [Warning] Could not increase number of max_open_files to more than 16384 (request: 32132)
Apr 18 02:38:25 instance-1 kernel: type=1400 audit(1618681105.871:3080990): avc:  denied  { write } for  pid=12887 comm="mysqld" name="mysql-data" dev="sda2" ino=1454
Apr 18 02:38:25 instance-1 kernel: type=1300 audit(1618681105.871:3080990): arch=c000003e syscall=2 success=no exit=-13 a0=7ffddfabca10 a1=80042 a2=1b6 a3=88 items=0
Apr 18 02:38:25 instance-1 kernel: type=1327 audit(1618681105.871:3080990): proctitle="/usr/sbin/mysqld"
Apr 18 02:38:25 instance-1 mysqld[12887]: 2021-04-18  2:38:25 0 [Warning] Can't create test file /data/mysql/mysql-data/instance-1.lower-test
Apr 18 02:38:25 instance-1 mysqld[12887]: /usr/sbin/mysqld: Can't create file '/home/mysql/log/error/mysql.err' (errno: 13 "Permission denied")
Apr 18 02:38:25 instance-1 mysqld[12887]: 2021-04-18  2:38:25 0 [ERROR] mysqld: File '/home/mysql/log/binary/mysql-bin.index' not found (Errcode: 13 "Permission denie
Apr 18 02:38:25 instance-1 mysqld[12887]: 2021-04-18  2:38:25 0 [ERROR] Aborting
Apr 18 02:38:26 instance-1 systemd[1]: mariadb.service: main process exited, code=exited, status=1/FAILURE
Apr 18 02:38:26 instance-1 systemd[1]: Failed to start MariaDB 10.4.18 database server.

$ ssh -i [rsa 개인 키 경로] [접속ID]@[IP주소]

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@.
Please contact your system administrator.
Add correct host key in C:\\Users\\zmfjs/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in C:\\Users\\zmfjs/.ssh/known_hosts:2
ECDSA host key for ***.***.***.*** has changed and you have requested strict checking.
Host key verification failed.

Welcome to Ubuntu 18.04.5 LTS (GNU/Linux 5.4.0-1041-oracle x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Sat Apr 17 16:24:10 UTC 2021

  System load:  0.14              Processes:           113
  Usage of /:   3.2% of 44.97GB   Users logged in:     0
  Memory usage: 27%               IP address for ens3: 10.0.0.13
  Swap usage:   0%


0 packages can be updated.
0 of these updates are security updates.

New release '20.04.2 LTS' available.
Run 'do-release-upgrade' to upgrade to it.



The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

See "man sudo_root" for details.

ubuntu@devwithpug:~$

$ sudo passwd root
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

$ date
Sat Apr 17 16:46:38 UTC 2021

$ sudo dpkg-roconfigigure tzdata

Current default time zone: 'Asia/Seoul'
Local time is now:      Sun Apr 18 01:47:09 KST 2021.
Universal Time is now:  Sat Apr 17 16:47:09 UTC 2021.

$ sudo apt update

$ sudo apt upgrade

$ sudo apt-get install software-properties-common
$ sudo apt-key adv --fetch-keys 'https://mariadb.org/mariadb_release_signing_key.asc'
$ sudo add-apt-repository 'deb [arch=amd64,arm64,ppc64el] https://mirror.yongbok.net/mariadb/repo/10.5/ubuntu bionic main'

$ sudo apt update
$ sudo apt install mariadb-server

$ sudo mysql_secure_installation

Enter current password for root (enter for none):
OK, successfully used password, moving on...

You already have your root account protected, so you can safely answer 'n'.

Switch to unix_socket authentication [Y/n] n
 ... skipping.

Change the root password? [Y/n] y
New password:
Re-enter new password:
Password updated successfully!
Reloading privilege tables..
 ... Success!

By default, a MariaDB installation has an anonymous user, allowing anyone
to log into MariaDB without having to have a user account created for
them.  This is intended only for testing, and to make the installation
go a bit smoother.  You should remove them before moving into a
production environment.

Remove anonymous users? [Y/n] y
 ... Success!

Normally, root should only be allowed to connect from 'localhost'.  This
ensures that someone cannot guess at the root password from the network.

Disallow root login remotely? [Y/n] n
 ... skipping.

By default, MariaDB comes with a database named 'test' that anyone can
access.  This is also intended only for testing, and should be removed
before moving into a production environment.

Remove test database and access to it? [Y/n] y
 - Dropping test database...
 ... Success!
 - Removing privileges on test database...
 ... Success!

Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.

Reload privilege tables now? [Y/n] y
 ... Success!

Cleaning up...

All done!  If you've completed all of the above steps, your MariaDB
installation should now be secure.

Thanks for using MariaDB!

$ service mysql status

● mariadb.service - MariaDB 10.5.9 database server
   Loaded: loaded (/lib/systemd/system/mariadb.service; enabled; vendor preset: enabled)
  Drop-In: /etc/systemd/system/mariadb.service.d
           └─migrated-from-my.cnf-settings.conf
   Active: active (running)

$ mysql -u root -p

Enter password:

Welcome to the MariaDB monitor.  Commands end with ; or \g.

MariaDB [(none)]> create database devwithpug;
Query OK, 1 row affected (0.000 sec)

MariaDB [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| devwithpug         |
| information_schema |
| mysql              |
| performance_schema |
+--------------------+
4 rows in set (0.000 sec)

MariaDB [(none)]> CREATE USER 'root'@'%' IDENTIFIED VIA mysql_native_password USING PASSWORD ("password");
Query OK, 0 rows affected (0.003 sec)

MariaDB [(none)]> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION;
Query OK, 0 rows affected (0.001 sec)

MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.000 sec)

$ sudo vi /etc/mysql/my.cnf

[client-server]
# Port or socket location where to connect
port = 3306

$ sudo vi /etc/mysql/mariadb.conf.d/50-server.cnf

[mysqld]

#bind-address            = 127.0.0.1
bind-address = 0.0.0.0

$ sudo systemctl restart mysql

$ netstat -nap | grep LISTEN
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      -                   
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      -                   
tcp6       0      0 :::111                  :::*                    LISTEN      -                   
tcp6       0      0 :::22                   :::*                    LISTEN      - 

$ sudo iptables -I INPUT 5 -i ens3 -p tcp --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT

$ sudo iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination
ACCEPT     all  --  anywhere             anywhere             state RELATED,ESTABLISHED
ACCEPT     icmp --  anywhere             anywhere
ACCEPT     all  --  anywhere             anywhere
ACCEPT     udp  --  anywhere             anywhere             udp spt:ntp
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:mysql state NEW,ESTABLISHED