【环境说明】
服务器版本 redHat5.3
mysql版本 MySQL5.6.22
freeradius版本 2.1.12
【问题描述】
配置好freeradius的sql.conf中的数据库地址，以及登录用户名和密码后，使用“radiusd -X”调试模式启动radius，控制台一直在漫长的输出尝试连接mysql的日 志，如下所示：
2014-12-30 09:27:39 DEBUG sql.c 93 - [RLM_SQL] Starting 0
2014-12-30 09:27:39 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #0
2014-12-30 09:27:39 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #0
2014-12-30 09:27:56 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #0
2014-12-30 09:27:56 DEBUG sql.c 93 - [RLM_SQL] Starting 1
2014-12-30 09:27:56 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #1
2014-12-30 09:27:56 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #1
2014-12-30 09:28:12 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #1
2014-12-30 09:28:12 DEBUG sql.c 93 - [RLM_SQL] Starting 2
2014-12-30 09:28:12 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #2
2014-12-30 09:28:12 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #2
2014-12-30 09:28:28 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #2
2014-12-30 09:28:28 DEBUG sql.c 93 - [RLM_SQL] Starting 3
2014-12-30 09:28:28 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #3
2014-12-30 09:28:28 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #3
2014-12-30 09:28:44 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #3
2014-12-30 09:28:44 DEBUG sql.c 93 - [RLM_SQL] Starting 4
2014-12-30 09:28:44 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #4
2014-12-30 09:28:44 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #4
2014-12-30 09:29:00 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #4
2014-12-30 09:29:00 DEBUG sql.c 93 - [RLM_SQL] Starting 5
2014-12-30 09:29:00 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #5
2014-12-30 09:29:00 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #5
2014-12-30 09:29:17 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #5
2014-12-30 09:29:17 DEBUG sql.c 93 - [RLM_SQL] Starting 6
2014-12-30 09:29:17 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #6
2014-12-30 09:29:17 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #6
2014-12-30 09:29:32 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #6
2014-12-30 09:29:32 DEBUG sql.c 93 - [RLM_SQL] Starting 7
2014-12-30 09:29:32 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #7
2014-12-30 09:29:32 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #7
2014-12-30 09:29:48 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #7
2014-12-30 09:29:48 DEBUG sql.c 93 - [RLM_SQL] Starting 8
2014-12-30 09:29:48 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #8
2014-12-30 09:29:48 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #8
2014-12-30 09:30:04 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #8
2014-12-30 09:30:04 DEBUG sql.c 93 - [RLM_SQL] Starting 9
2014-12-30 09:30:04 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #9
2014-12-30 09:30:04 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #9
2014-12-30 09:30:21 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #9
2014-12-30 09:30:21 DEBUG sql.c 93 - [RLM_SQL] Starting 10
2014-12-30 09:30:21 INFO sql.c 54 - [RLM_SQL] Attempting to connect rlm_sql_mysql #10
2014-12-30 09:30:21 INFO sql_mysql.c 79 - [RLM_SQL_MYSQL] Starting connect to MySQL server for #10
2014-12-30 09:30:37 INFO sql.c 58 - [RLM_SQL] Connected new DB handle, #10
到99以后提示失败，经查阅相关资料，进行如下处理即解决问题
【解决办法】
原理：关闭mysql服务器连接的域名解析
步骤：
1 vim /usr/my.cnf; mysql5.6.22版的配置文件在/usr/下，编辑my.cnf，在[mysqld]下增加一行“skip-name-resovle”,保存退出；
2 重启mysql；
3 重新启动radius；
【可能存在问题】
mysql客户端连接服务器时，服务器会对客户端进行反向域名解析，因此这个是耗时多的原因，取消域名解析以后，mysql的权限表（user表）中将不能再使用类似localhost之类的主机名，而必须使用ip地址。
---- <仅供参考> ----