When doing in apache2.conf for site: LogLevel debug filter:warn I get log messages: [Mon Jun 01 12:42:36.422149 2015] [:debug] [pid 12456:tid 140189141825280] filter.c(270): [client 176.8.83.57:47404] prefetching 65536 bytes, referer: http://host/servers/12591.html I think, that is because filter does not report its 'module_name'
filter.c has nothing to do with mod_filter!