A busy night results in the 0.1 release of mod_ifier, it allows matching and rejection on arbitary incoming HTTP request headers, with helpers for User-Agent and Referer headers.
ie. DropReferer is now a synonym for “DropHeader Referer …”, and DropAgent is similarly processed as “DropHeader User-Agent ..”
There is a Debian x86 package for Sarge, and matching source package, along with brief instructions.
It seems stable and reliable. Next I need to look at URI matching, POST payload analysis, and the use of regular expressions instead of literal matches.