I had problems compiling http://heanet.dl.sourceforge.net/sourceforge/modauthmysql/mod_auth_mysql-2.9.0.tar.gz
on FreeBSD 5.3 with Apache 2. This patch helped.

 --md@hudora.de

--- mod_auth_mysql-2.9.0/mod_auth_mysql.c       Fri Feb 25 22:22:23 2005
+++ mod_auth_mysql-2.9.0-md/mod_auth_mysql.c    Sun Mar 20 09:47:18 2005
@@ -207,7 +207,8 @@
   #include "apr_strings.h"
   #include "apr_sha1.h"
   #include "apr_base64.h"
-  #include "crypt.h"
+// on FreeBSD 5.3 apache 2.0.53 there was no crypt.h, but unistd.h worked fine 
+  #include "unistd.h"
   #define LOG_ERROR(lvl, stat, rqst, msg)  \
          ap_log_rerror (APLOG_MARK, lvl, stat, rqst, msg)
   #define LOG_ERROR_1(lvl, stat, rqst, msg, parm)  \