用户'www-data'@'localhost的访问被拒绝-如何处理? [英] Access denied for user 'www-data'@'localhost - how to deal with that?

问题描述

昨天我遇到一个奇怪的问题.我的服务器运行的是Debian，安装了PHP 4.4.4-8和mysql 5.5.9.该服务器为多个网站提供服务. 出于某种原因，当我尝试加载网页时，随机出现错误用户'www-data'@'localhost'的访问被拒绝(使用密码:否)". 如果单击刷新，页面将正常加载，但单击几次后，该消息将再次出现.该页面用于连接到mysql服务器的用户名不是www-data.

I face with a strange problem yesterday. I have server running Debian with installed PHP 4.4.4-8 and mysql 5.5.9. That server serves a several websites. For some reason randomly I get that error "Access denied for user 'www-data'@'localhost' (using password: NO)" when I try to load the webpage. If I hit refresh the page loads normally, but afer several clicks that message appears again. Username which that page use to connect to mysql server is not www-data.

有人遇到过类似的问题吗?

Does anyone has faced similar problem ?

推荐答案

www-data是运行apache和php的Debian用户.如果您在没有有效连接的情况下尝试查询，则php/mysql将尝试使用<unix-user>@localhost创建无密码的连接.这是www-data@localhost (using password:NO)的来源.

www-data is the Debian user that runs apache and php. If you attempt a query when you don't have a valid connection, php/mysql will attempt to create a connection using <unix-user>@localhost with no password. This is where www-data@localhost (using password:NO) is coming from.

这种情况现在开始发生的最可能原因(尽管它已经运行了两年很好)是您的数据库负载已增加到某些连接无法成功的地步(可能是由于max_connections造成的，或者max_user_connections；尽管这也可能是由其他限制(例如内存，线程等)引起的.发生这种情况时，您对mysql_connect的调用将发出错误消息，并返回FALSE.如果您未能检测到此失败，则您的下一个mysql调用(可能是mysql_query或mysql_select_db)将尝试连接到www-data @ localhost，从而引起您所遇到的问题.

The most likely reason that this has started happening now (though it has been running fine for 2-years prior) is that your db load has increased to the point where some connections are unable to succeed (probably due to max_connections, or max_user_connections; though this can also result from other limits like memory, threads, etc). When this happens, your call to mysql_connect will emit an error message, and return FALSE. If you fail to detect this failure, then your next mysql call (probably mysql_query, or mysql_select_db) will attempt the connection to www-data@localhost -- thus causing the problem you're seeing.

我建议启用错误报告和错误显示(如@DarkMantis建议):

I suggest enabling error reporting, and error display (as suggested by @DarkMantis) :

ini_set('error_reporting', E_ALL|E_STRICT);
ini_set('display_errors', 1);

另外，请确保对mysql_connect的调用是 not ，并以@符号开头；并确保检查返回值.它应该看起来像这样:

Also, be sure that your call to mysql_connect is not preceded by a @ sign; and make sure to check the return value. It should look something like this:

$cxn = mysql_connect('localhost','yourusername','yourpassword');
if( $cxn === FALSE ) {  die('mysql connection error: '.mysql_error()); }

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