mysqlにリモートで接続できないのはなぜですか？

リモートでアクセスできるようにmysqlを設定する必要があります。これはファイルの一部です/etc/mysql/my.cnf。

[mysqld]
#
# * Basic Settings
#
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
#bind-address       = 127.0.0.1
bind-address        = 0.0.0.0
#
# * Fine Tuning
#
key_buffer      = 16M
max_allowed_packet  = 16M
thread_stack        = 192K
thread_cache_size       = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover         = BACKUP
#max_connections        = 100
#table_cache            = 64
#thread_concurrency     = 10
#
# * Query Cache Configuration
#
query_cache_limit   = 1M
query_cache_size        = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file        = /var/log/mysql/mysql.log
#general_log             = 1
#
# Error log - should be very few entries.
#
log_error = /var/log/mysql/error.log
#
# Here you can see queries with especially long duration
#log_slow_queries   = /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
#       other settings you may need to change.
#server-id      = 1
#log_bin            = /var/log/mysql/mysql-bin.log
expire_logs_days    = 10
max_binlog_size         = 100M
#binlog_do_db       = include_database_name
#binlog_ignore_db   = include_database_name
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem

また、すべての指示をコメントアウトしようとしましたが、bind-address問題は解決されませんでした。

コマンド出力netstat -tlnep:

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       User       Inode       PID/Program name
tcp        0      0 0.0.0.0:21              0.0.0.0:*               LISTEN      0          3159847     6038/vsftpd
tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN      0          10112       1372/master
tcp        0      0 0.0.0.0:443             0.0.0.0:*               LISTEN      0          15680697    53108/nginx: worker
tcp        0      0 0.0.0.0:2277            0.0.0.0:*               LISTEN      0          11247       1109/sshd
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN      105        23269036    57272/mysqld
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      0          15680696    53108/nginx: worker
tcp6       0      0 :::25                   :::*                    LISTEN      0          10113       1372/master
tcp6       0      0 :::443                  :::*                    LISTEN      0          15680698    53108/nginx: worker
tcp6       0      0 :::2277                 :::*                    LISTEN      0          11249       1109/sshd

これで、ローカルホストではmysqlに接続できますが、リモートホストでは接続できません。リモートホストからの接続中にエラーが発生しました：ERROR 2003 (HY000): Can't connect to MySQL server on '<my server ip address>' (110)

Telnet はポート 3306 でサーバー IP に接続することもできません。

いくつかのシステム情報：

uname -a
Linux webdevgranat 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

iptables -S
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT


mysql> SELECT VERSION();
+-------------------------+
| VERSION()               |
+-------------------------+
| 5.5.54-0ubuntu0.14.04.1 |
+-------------------------+
1 row in set (0.00 sec)

また、開いているポート（例：ここ）、3306ポートではないとマークされます。閉鎖しかし、ろ過。

ufw ファイアウォールが無効です。