Apache配置：只允许有两个带有SSL的子域名。

在Apache的配置文件中，可以使用以下代码示例来实现只允许有两个带有SSL的子域名：

<VirtualHost *:80>
    ServerName example.com
    Redirect permanent / https://example.com/
</VirtualHost>

<VirtualHost *:443>
    ServerName example.com

    # SSL Configuration
    SSLEngine on
    SSLCertificateFile /path/to/ssl_certificate.crt
    SSLCertificateKeyFile /path/to/ssl_certificate.key

    # Other configuration options

</VirtualHost>

<VirtualHost *:443>
    ServerName subdomain1.example.com

    # SSL Configuration
    SSLEngine on
    SSLCertificateFile /path/to/ssl_certificate1.crt
    SSLCertificateKeyFile /path/to/ssl_certificate1.key

    # Other configuration options

</VirtualHost>

<VirtualHost *:443>
    ServerName subdomain2.example.com

    # SSL Configuration
    SSLEngine on
    SSLCertificateFile /path/to/ssl_certificate2.crt
    SSLCertificateKeyFile /path/to/ssl_certificate2.key

    # Other configuration options

</VirtualHost>

# Redirect all other subdomains to HTTPS
<VirtualHost *:80>
    ServerName *.example.com
    Redirect permanent / https://%{HTTP_HOST}%{REQUEST_URI}
</VirtualHost>

在上述配置中，首先定义了一个监听80端口的虚拟主机，将所有访问主域名（example.com）的请求重定向到HTTPS。然后定义了三个监听443端口的虚拟主机，分别对应主域名和两个子域名，每个虚拟主机都配置了相应的SSL证书和密钥。最后，通过另一个监听80端口的虚拟主机，将所有其他子域名的请求重定向到HTTPS。这样就实现了只允许有两个带有SSL的子域名的配置。