尝试连接到不同服务器中的数据库：
命令行
php symfony configure:database "mysql:host=<IP>;dbname=<db_name>" <username> <password>
数据库.yml
all:
doctrine:
class: sfDoctrineDatabase
param:
dsn: 'mysql:host=<IP>;dbname=<db_name>'
username: <username>
password: <password>
获取错误：
PDO连接错误：SQLSTATE[HY000][2002]连接尝试失败，因为连接方在一段时间后没有正确响应，或者由于连接的主机没有响应而建立的连接失败
您需要从该主机授予用户访问权限。类似的东西
GRANT ALL ON mydb.* TO 'someuser'@'somehost';
点击此处了解更多信息。
Apologies for making this a bit long.
This is the server my.cnf
[mysqld]
# Settings user and group are ignored when systemd is used (fedora >= 15).
# If you need to run mysqld under different user or group,
# customize your systemd unit file for mysqld according to the
# instructions in http://fedoraproject.org/wiki/Systemd
user=mysql
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Semisynchronous Replication
# http://dev.mysql.com/doc/refman/5.5/en/replication-semisync.html
# uncomment next line on MASTER
;plugin-load=rpl_semi_sync_master=semisync_master.so
# uncomment next line on SLAVE
;plugin-load=rpl_semi_sync_slave=semisync_slave.so
# Others options for Semisynchronous Replication
;rpl_semi_sync_master_enabled=1
;rpl_semi_sync_master_timeout=10
;rpl_semi_sync_slave_enabled=1
# http://dev.mysql.com/doc/refman/5.5/en/performance-schema.html
;performance_schema
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid