There are times when a problem can be caused by an application server, proxy server or the web server itself.
To dump HTTP requests and responses, the mod_dumpio Apache web server module can be used.
Setting up mod_dumpio is simple and straight forward.
Once these directives are enabled, entries similar to the following will be written to the error_log each time a request is received, or a response is sent:
[Mon Oct 12 12:13:14 2016] [debug] mod_dumpio.c(103): mod_dumpio: dumpio_in [getline-blocking] 0 readbytes [Mon Oct 12 12:13:14 2016] [debug] mod_dumpio.c(51): mod_dumpio: dumpio_in (data-HEAP): 16 bytes [Mon Oct 12 12:13:14 2016] [debug] mod_dumpio.c(67): mod_dumpio: dumpio_in (data-HEAP): GET / HTTP/1.1rn
NOTE: mod_dumpio adds some additional overhead to request processing, and the configuration directives will require a server restart.
A graceful restart can be used to avoid killing active connections.