Log authentication attempts to syslog

Fixes #6146

Signed-off-by: Michal Čihař <michal@cihar.com>

ChangeLog

@@ -3,6 +3,7 @@ phpMyAdmin - ChangeLog
 
 4.7.0.0 (not yet released)
 - issue #11924 Remove caching of server information
+- issue #6146  Log authentication attempts to syslog
 
 4.6.0.0 (not yet released)
 + issue #11456 Disabled storage engines
@@ -127,7 +128,6 @@ phpMyAdmin - ChangeLog
 
 4.3.14.0 (not yet released)
 
-
          --- Older ChangeLogs can be found on our project website ---
                      http://www.phpmyadmin.net/old-stuff/ChangeLogs/
 

libraries/logging.lib.php

@@ -22,5 +22,11 @@ function PMA_logUser($user, $status = 'ok')
         apache_note('userID', $user);
         apache_note('userStatus', $status);
     }
+    if (function_exists('syslog')) {
+        @syslog(
+            LOG_AUTHPRIV,
+            'phpMyAdmin: ' . $user . ' (' . $status . ') from ' . $_SERVER['REMOTE_ADDR']
+        );
+    }
 }