Translated from: http://blog.csdn.net/chengyuqiang/article/details/54285857
1, the program error :
Com.mysql.jdbc.exceptions.jdbc4.CommunicationsException:Communications Link
2. Try to connect to the database remotely :
[Email protected] ~]# mysql-h192.168.1.165-uroot-p123456
ERROR 2003 (HY000): Can ' t connect to MySQL server on ' 192.168.1.165 ' (113)
3, the problem was found, can not connect to the remote database.
4. Test if you can ping the remote machine
[[email protected] ~]# Ping 192.168.1.165
PING 192.168.1.165 (192.168.1.165) bytes of data.
Bytes from 192.168.1.165:icmp_seq=1 ttl=128 time=0.776 ms
Bytes from 192.168.1.165:icmp_seq=2 ttl=128 time=1.26 ms
Bytes from 192.168.1.165:icmp_seq=3 ttl=128 time=1.19 ms
^c
---192.168.1.165 ping statistics---
3 Packets transmitted, 3 received, 0% packet loss, time 2008ms
RTT Min/avg/max/mdev = 0.776/1.078/1.268/0.215 ms
Indicates that the network is connected, and then test the following port number
5. Log on to the database side
[Email protected] ~]# mysql-uroot-p123456
Welcome to the MariaDB Monitor. Commands End With; or \g.
Your MariaDB Connection ID is 11
Server VERSION:5.5.52-MARIADB MariaDB Server
Copyright (c), Oracle, MariaDB Corporation Ab and others.
Type ' help ', ' or ' \h ' for help. Type ' \c ' to clear the current input statement.
MariaDB [(None)]> select User,host,password from Mysql.user;
+------+-----------+-------------------------------------------+
| user | Host | password |
+------+-----------+-------------------------------------------+
| Root | localhost | *6bb4837eb74329105ee4568dda7dc67ed2ca2ad9 |
| Root | 127.0.0.1 | *6bb4837eb74329105ee4568dda7dc67ed2ca2ad9 |
| Root | :: 1 | *6bb4837eb74329105ee4568dda7dc67ed2ca2ad9 |
+------+-----------+-------------------------------------------+
Add
MariaDB [(None)]> Grant all privileges on * * to ' root ' @ '% ' identified by ' 123456 ';
Query OK, 0 rows Affected (0.00 sec)
MariaDB [(None)]> flush privileges;
Query OK, 0 rows Affected (0.00 sec)
Remote Access again:
[Email protected] ~]# mysql-h192.168.1.165-uroot-p123456
ERROR 2003 (HY000): Can ' t connect to MySQL server on ' 192.168.1.165 ' (113)
6, or cannot connect to the database, may not be able to access the port number, test again
[[Email protected] ~]# telnet 192.168.1.165 3306
Trying 192.168.1.165 ...
Telnet:connect to address 192.168.1.165:no route to host
Find out where the problem is and the firewall blocks the port number.
7, directly shut down the firewall can .
[Email protected] ~]# systemctl disable FIREWALLD
Removed Symlink/etc/systemd/system/dbus-org.fedoraproject.firewalld1.service.
Removed Symlink/etc/systemd/system/basic.target.wants/firewalld.service.
[[Email protected] ~]# service FIREWALLD stop
Redirecting To/bin/systemctl Stop Firewalld.service
Remote Access again
[[Email protected] ~]# telnet 192.168.1.165 3306
Trying 192.168.1.165 ...
Telnet:connect to address 192.168.1.165:no route to host
[Email protected] ~]# mysql-h192.168.1.165-uroot-p123456
Welcome to the MariaDB Monitor. Commands End With; or \g.
Your MariaDB Connection ID is 7
Server VERSION:5.5.52-MARIADB MariaDB Server
Copyright (c), Oracle, MariaDB Corporation Ab and others.
Type ' help ', ' or ' \h ' for help. Type ' \c ' to clear the current input statement.
MariaDB [(None)]>
It worked.
ERROR 2003 (HY000): Can ' t connect to MySQL server issue
Solution Summary:
1, determine the remote machine firewall shutdown, or the firewall allows 3306 port number
2. Make sure the database allows remote access via the statement grant all privileges on * * to ' root ' @ '% ' identified by ' 123456 '.
"Go" ERROR 2003 (HY000): Can ' t connect to MySQL server on ' 192.168.1.165 ' (113)