ssl_buffer_size
The `ssl_buffer_size` directive sets the size of the buffer used for reading SSL data.
Description
The ssl_buffer_size directive in NGINX specifies the buffer size allocated for reading SSL handshake messages. This buffer size impacts the reception of SSL data during both handshake and data transfer operations. By default, NGINX allows the buffer size to dynamically adjust according to the needs of the specific SSL library being used, but it can be explicitly defined for optimizations or specific server behavior.
When using the directive, you specify a buffer size, which should conform to the expected size for your use case. Setting this value too low may lead to performance issues or improperly handled larger messages, whereas setting it excessively high could waste memory resources. This value is used internally by NGINX during the SSL handshake phase—where it negotiates secure connections—and during the actual TLS data transmission, thus affecting the overall efficiency of SSL operations.
The directive can be placed within both the http and server contexts, allowing you flexibility in defining buffer sizes at different levels of your NGINX configuration. For servers handling high volumes of SSL traffic, fine-tuning the ssl_buffer_size can lead to improved performance and a reduction in latency.
Config Example
http {
ssl_buffer_size 16k;
}
server {
listen 443 ssl;
ssl_buffer_size 8k;
}
Ensure the buffer size is appropriate for the expected maximum SSL record size to avoid message truncation.
Be cautious when setting very high values, as this might lead to unnecessary memory usage. If your server handles many connections, you should balance this setting.