For some reason, the www/apache22 FreeBSD port does not support the mod_substitute module even though it’s bundled standard with Apache. The following patch enables building of this useful module, which compiles and works just fine out of the box.
UPDATE: After e-mailing the maintainer, this patch has been officially merged into the port as of March 29, 2011.
Continue reading [PATCH] Add mod_substitute to www/apache22 in FreeBSD