mod_logio
Logging of input and output bytes per request
Extension
mod_logio.c
logio_module

This module provides the logging of input and output number of bytes received/sent per request. The numbers reflect the actual bytes as received on the network, which then takes into account the headers and bodies of requests and responses. The counting is done before SSL/TLS on input and after SSL/TLS on output, so the numbers will correctly reflect any changes made by encryption.

This module requires mod_log_config.

When KeepAlive connections are used with SSL, the overhead of the SSL handshake is reflected in the byte count of the first request on the connection. When per-directory SSL renegotiation occurs, the bytes are associated with the request that triggered the renegotiation.

mod_log_config
Apache Log Files

# Custom Log Formats

This modules adds two new logging directives. The characteristics of the request itself are logged by placing "`%`" directives in the format string, which are replaced in the log file by the values as follows:

Format String | Description
--- | ---
`%...I` | Bytes received, including request and headers, cannot be zero.
`%...O` | Bytes sent, including headers, cannot be zero.

Usually, the functionality is used like this:

Combined I/O log format:
  `"%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\" %I %O"`