Isn't the last close AUTH in the original sub auth_logging supposed to be close LOG?
open (LOG, ">>$auth_log_file") || &cgierr("unable to open log file: $auth_log_file. Reason: $!\n");
flock (LOG, 2) unless (!$db_use_flock);
print LOG "$uid $action at $time on $date from $ENV{'REMOTE_HOST'}\n";
close AUTH; # releases file lock.
open (LOG, ">>$auth_log_file") || &cgierr("unable to open log file: $auth_log_file. Reason: $!\n");
flock (LOG, 2) unless (!$db_use_flock);
print LOG "$uid $action at $time on $date from $ENV{'REMOTE_HOST'}\n";
close AUTH; # releases file lock.