SSL(Secure Sockets Layer 安全套接层)，是为网络通信提供安全及数据完整性的一种安全协议，其利用公开密钥数据加密(Encryption)技术，确保数据在网络上之传输过程中不会被截取及窃听。
SSL协议提供的服务主要有：
认证用户和服务器，确保数据发送到正确的客户机和服务器；
加密数据以防止数据中途被窃取；
维护数据的完整性，确保数据在传输过程中不被改变。
为了在MySQL服务器和客户端之间建立SSL联接，服务器系统必须满足：
操作系统安装有OpenSSL或yaSSL；
安装的MySQL版本必须支持SSL。
本文中使用OpenSSL。
一、前提
1. 检查操作系统是否满足要求：
shell>rpm -qa | grep openssl #检查是否安装OpenSSL。MySQL需要openssl的共享库。
//如果没有安装，则进行安装，官网： http://www.openssl.org
2. 检查数据库是否满足要求
mysql> show global variables like ‘have%ssl’; #检查是否支持ssl。NO表示不支
//持，DISABLE表示支持但未使用，如何启用见下文。
+---------------+----------+
| Variable_name | Value |
+---------------+----------+
| have_openssl | DISABLED |
| have_ssl | DISABLED |
+---------------+----------+
如果是使用编译好的二进制，默认都支持，如果自行编译，针对5.5版本，需要使用
cmake . -DWITH_SSL=system选项。
为使客户端能够使用SSL方式进行连接，需要配置合适的证书和密钥文件，以及为用
户授予合适的权限。
二、为MySQL生成证书和密钥
1. 前提
shell>mkdir -p /db/ssl
shell>cd /db/ssl
2. 创建认证机构的数字认证证书，后续服务器端和客户端的证书都使用该认证机构进行签署。
shell>openssl genrsa 2048 > ca-key.pem
Generating RSA private key, 2048 bit long modulus
………+++
…………………………………………………………………………………………………..+++
e is 65537 (0×10001)
shell>openssl req -new -x509 -nodes -days 3600 -key ca-key.pem -out ca-cert.pem
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter ‘.’, the field will be left blank.
Country Name (2 letter code) [GB]:CN
State or Province Name (full name) [Berkshire]:Beijing
Locality Name (eg, city) [Newbury]:Beijing
Organization Name (eg, company) [My Company Ltd]:CA
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server’s hostname) []:
Email Address []:
3. 创建服务器端证书
shell>openssl req -newkey rsa:2048 -days 3600 -nodes -keyout server-key.pem \
-out server-req.pem
Generating a 2048 bit RSA private key
……………….+++
…………………………+++
writing new private key to ‘server-key.pem’
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter ‘.’, the field will be left blank.
Country Name (2 letter code) [GB]:CN
State or Province Name (full name) [Berkshire]:Beijing
Locality Name (eg, city) [Newbury]:Beijing
Organization Name (eg, company) [My Company Ltd]:CH
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server’s hostname) []:mysqlserver
Email Address []:
Please enter the following ‘extra’ attributes
to be sent with your certificate request
A challenge password []:abc123
An optional company name []:
shell>openssl rsa -in server-key.pem -out server-key.pem
//移除server-key中的passphrase[可选]
writing RSA key
shell>openssl x509 -req -in server-req.pem -days 3600 -CA ca-cert.pem -CAkey \
ca-key.pem -set_serial 01 -out server-cert.pem
//签署服务端证书
Signature ok
subject=/C=CN/ST=Hangzhou/L=Hangzhou/O=CH/CN=mysqlserver
Getting CA Private Key
4. 创建客户端证书
shell>openssl req -newkey rsa:2048 -days 3600 -nodes -keyout \
client-key.pem -out client-req.pem
Generating a 2048 bit RSA private key
………………………………………………………………………………………+++
…+++
writing new private key to ‘client-key.pem’
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter ‘.’, the field will be left blank.
Country Name (2 letter code) [GB]:CN
State or Province Name (full name) [Berkshire]:Beijing
Locality Name (eg, city) [Newbury]:Beijing
Organization Name (eg, company) [My Company Ltd]:CH
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server’s hostname) []:mysqlclient
Email Address []:
Please enter the following ‘extra’ attributes
to be sent with your certificate request
A challenge password []:abc123
An optional company name []:
shell>openssl rsa -in client-key.pem -out client-key.pem
//移除client-key中的passphrase[可选]
writing RSA key
shell>openssl x509 -req -in client-req.pem -days 3600 -CA ca-cert.pem \
-CAkey ca-key.pem -set_serial 01 -out client-cert.pem
//签署客户端证书
Signature ok
subject=/C=CN/ST=Hangzhou/L=Hangzhou/O=CH/CN=mysqlclient
Getting CA Private Key
5. 生成完毕后，验证步骤如下
shell>openssl verify -CAfile ca-cert.pem server-cert.pem client-cert.pem
server-cert.pem: OK
client-cert.pem: OK
6. 综上步骤，生成如下文件：
ca-cert.pem 在服务器端和客户端都是用 ssl-ca=ca-cert.pem
server-cert.pem,server-key.pem 服务器端指定 ssl-cert=server-cert.pem 和 \
ssl-key=server-key.pem
client-cert.pem,client-key.pem 客户端指定 ssl-cert=client-cert.pem 和 \
ssl-key=client-key.pem
三、配置SSL连接
实现使用SSL进行配置和赋权的两种方案
1. 方案1
Server:
1）在服务器端的配置文件my.cnf中添加如下参数：
[mysqld]
ssl-cert=/db/ssl/server-cert.pem
ssl-key=/db/ssl/server-key.pem
2）重启mysqld。
用户赋权，用GRANT语句的REQUIRE SSL选项
mysql>create user user@localhost identified by ‘abc’;
mysql>grant select on testdb.* to user@localhost require ssl;
Client:
mysql -u user -pabc -P 3300 ssl-ca=ca-cert.pem
2. 方案2
Server:
1）在服务器端的配置文件my.cnf中添加如下参数：
[mysqld]
ssl-ca=/db/ssl/ca-cert.pem
ssl-cert=/db/ssl/server-cert.pem
ssl-key=/db/ssl/server-key.pem
2）重启mysqld。
用户赋权，用GRANT语句的REQUIRE x509选项
mysql>create user user@localhost identified by ‘abc’;
mysql>grant select on testdb.* to user@localhost require x509;
Client:
mysql -u user -pabc -P 3300 ssl-ca=ca-cert.pem ssl-key=client-key.pem \
ssl-cert=client-cert.pem
注意：方案2的验证要求更严格，需要指定key和cert，因此推荐使用方案2。
四、检查
1. 配置完成后，可以如下方式查看自身对ssl的支持：
mysql> show global variables like ‘%ssl%’; #查看服务器是否支持SSL连接
+---------------+-------------------------+
| Variable_name | Value |
+---------------+-------------------------+
| have_openssl | YES |
| have_ssl | YES |
| ssl_ca | /db/ssl/ca-cert.pem |
| ssl_capath | |
| ssl_cert | /db/ssl/server-cert.pem |
| ssl_cipher | |
| ssl_key | /db/ssl/server-key.pem |
+---------------+-------------------------+
mysql> SHOW STATUS LIKE ‘Ssl_cipher’; #查看本连接是否是SSL加密的连接
+---------------+--------------------+
| Variable_name | Value |
+---------------+--------------------+
| Ssl_cipher | DHE-RSA-AES256-SHA |
+---------------+--------------------+
1. 通过抓包工具，相同的select * from t1命令，可以明显看到加密前后包信息的不同。
1)加密前：
2)加密后：
------------------------------------------------------------------------------------------
附：SSL协议的工作方式简介
客户端要收发几个握手信号：
发送一个“ClientHello”消息，说明它支持的密码算法列表、压缩方法及最高协议版本，也发送稍后将被使用的随机数。
然后收到一个“ServerHello”消息，包含服务器选择的连接参数，源自客户端初期所提供的“ClientHello”。
当双方知道了连接参数，客户端与服务器交换证书（依靠被选择的公钥系统）。这些证书通常基于X.509，不过已有草案支持以OpenPGP为基础的证书。
服务器请求客户端公钥。客户端有证书即双向身份认证，没证书时随机生成公钥。
客户端与服务器通过公钥保密协商共同的主私钥（双方随机协商），这通过精心谨慎设计的伪随机数功能实现。结果可能使用Diffie-Hellman交换，或简化的公钥加密，双方各自用私钥解密。所有其他关键数据的加密均使用这个“主密钥”。
