Task: MySQL Server Remote Access

You need type the following commands which will allow remote connections to a mysql server.

Step # 1: Login Using SSH (if server is outside your data center)

First, login over ssh to remote MySQL database server. You may need to login to your MySQL server as the root user:

ssh user@server1.cyberciti.biz
### login as the root using su or sudo ##
su
# or use sudo  ##
sudo -i

OR directly login as root user if allowed:

ssh root@server1.cyberciti.biz

Step # 2: Edit the my.cnf file

Once connected you need to edit the MySQL server configuration file my.cnf using a text editor such as vi:

• If you are using Debian/Ubuntu Linux file is located at /etc/mysql/my.cnf location.
• If you are using Red Hat Linux/Fedora/Centos Linux file is located at /etc/my.cnflocation.
• If you are using FreeBSD you need to create a file /var/db/mysql/my.cnf location.

Edit the /etc/my.cnf, run:
# vi /etc/my.cnf

Step # 3: Once file opened, locate line that read as follows

[mysqld] 

Make sure line skip-networking is commented (or remove line) and add following line

bind-address=YOUR-SERVER-IP

For example, if your MySQL server IP is 65.55.55.2 then entire block should be look like as follows:

[mysqld]
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
language        = /usr/share/mysql/English
bind-address    = 65.55.55.2  #应该可以注掉它
# skip-networking
....
..
....

Where,

• bind-address: IP address to bind to.
• skip-networking : Do not listen for TCP/IP connections at all. All interaction with mysqld must be made via Unix sockets. This option is highly recommended for systems where only local requests are allowed. Since you need to allow remote connection this line should be removed from my.cnf or put it in comment state.

Step# 4 Save and Close the file

If you are using Debian / Ubuntu Linux, type the following command to restart the mysql server:
# /etc/init.d/mysql restart
OR
# systemctl restart mysql
If you are using RHEL / CentOS / Fedora / Scientific Linux, type the following command to restart the mysql server:
# /etc/init.d/mysqld restart
OR
# systemctl restart mysqld
If you are using FreeBSD, type the following command to restart the mysql server:
# /usr/local/etc/rc.d/mysql-server restart
OR
# service mysql-server restart

Step # 5 Grant access to remote IP address

Connect to mysql server:
$ mysql -u root -p mysql

GRANT ACCESS TO A NEW DATABASE

If you want to add a new database called foo for user bar and remote IP 202.54.10.20 then you need to type the following commands at mysql> prompt:mysql> CREATE DATABASE foo;
mysql> GRANT ALL ON foo.* TO bar@'202.54.10.20' IDENTIFIED BY 'PASSWORD';

HOW DO I GRANT ACCESS TO AN EXISTING DATABASE?

Let us assume that you are always making connection from remote IP called 202.54.10.20 for database called webdb for user webadmin, To grant access to this IP address type the following command At mysql> prompt for existing database, enter:
mysql> update db set Host='202.54.10.20' where Db='webdb';
mysql> update user set Host='202.54.10.20' where user='webadmin';

Step # 6: Logout of MySQL

Type exit command to logout mysql:mysql> exit

Step # 7: Open port 3306

You need to open TCP port 3306 using iptables or BSD pf firewall.

A SAMPLE IPTABLES RULE TO OPEN LINUX IPTABLES FIREWALL

/sbin/iptables -A INPUT -i eth0 -p tcp --destination-port 3306 -j ACCEPT

OR only allow remote connection from your web server located at 10.5.1.3:

/sbin/iptables -A INPUT -i eth0 -s 10.5.1.3 -p tcp --destination-port 3306 -j ACCEPT

OR only allow remote connection from your lan subnet 192.168.1.0/24:

/sbin/iptables -A INPUT -i eth0 -s 192.168.1.0/24 -p tcp --destination-port 3306 -j ACCEPT

Finally save all rules (RHEL / CentOS specific command):
# service iptables save

A SAMPLE FREEBSD / OPENBSD / NETBSD PF FIREWALL RULE ( /ETC/PF.CONF)

Use the following to open port # 3306 on a BSD based systems:

pass in on $ext_if proto tcp from any to any port 3306

OR allow only access from your web server located at 10.5.1.3:

pass in on $ext_if proto tcp from 10.5.1.3 to any port 3306  flags S/SA synproxy state

Step # 8: Test it

From your remote system or your desktop type the following command:
$ mysql -u webadmin -h 65.55.55.2 -p
Where,

• -u webadmin: webadmin is MySQL username
• -h IP or hostname: 65.55.55.2 is MySQL server IP address or hostname (FQDN)
• -p : Prompt for password

You can also use the telnet or nc command to connect to port 3306 for testing purpose:
$ echo X | telnet -e X 65.55.55.2 3306
OR
$ nc -z -w1 65.55.55.2 3306
Sample outputs:

Connection to 65.55.55.2 3306 port [tcp/mysql] succeeded!

vim /etc/mysql/my.cnf

#bind-address           = 127.0.0.1
#skip-networking

service mysql restart

mysql> GRANT ALL PRIVILEGES ON *.* TO 'USERNAME'@'%' IDENTIFIED BY 'PASSWORD' WITH GRANT OPTION;

mysql> GRANT ALL PRIVILEGES ON *.* TO 'USERNAME'@'1.2.3.4' IDENTIFIED BY 'PASSWORD' WITH GRANT OPTION;

SELECT * from information_schema.user_privileges where grantee like "'USERNAME'%";

mysql> FLUSH PRIVILEGES;

mysql -h HOST -u USERNAME -pPASSWORD

mysql> REVOKE ALL PRIVILEGES, GRANT OPTION FROM 'USERNAME'@'%';

mysql> REVOKE ALL PRIVILEGES, GRANT OPTION FROM 'USERNAME'@'1.2.3.4';

+-------------------------+---------------+-------------------------+--------------+
| GRANTEE                 | TABLE_CATALOG | PRIVILEGE_TYPE          | IS_GRANTABLE |
+-------------------------+---------------+-------------------------+--------------+
| 'USERNAME'@'%'          | def           | USAGE                   | NO           |
+-------------------------+---------------+-------------------------+--------------+