socket() failed (13: Permission denied) while connecting to upstream

/***************************************************************************

 *  socket() failed (13: Permission denied) while connecting to upstream

 * 说明：

 *     这个错误隐藏的挺深的，观察了许久，才从ps aux中的执行用户中找出来。

 *

 *                                         2016-9-26 深圳 南山平山村 曾剑锋

 **************************************************************************/

一、错误现象：

    // :: [alert] #: * socket() failed (: Permission denied) while connecting to upstream, client: 192.168.1.144, server: localhost, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "192.168.1.203"

二、原因：

    . # ps aux

        ......

         root     /sbin/klogd -n

         root     udhcpc -R -n -p /var/run/udhcpc.eth0.pid -i eth0

         root     nginx: master process /usr/sbin/nginx

         www-data nginx: worker process

         root     /usr/sbin/sshd

         root     /usr/sbin/telnetd -F

         root     php-cgi -b 127.0.0.1: -c /etc/php.ini

         root     {mysqld_safe} /bin/sh /usr/bin/mysqld_safe --pid-file=/run/mysql

         root     /usr/libexec/mysqld --basedir=/usr --datadir=/var/mysql --user=r

         root     -sh

         root     ps

    . 如上所示，1468进程执行用户是www-data无法访问到1485进程的php-cgi，因为这个root权限。

三、解决办法：

    cat /etc/nginx/nginx.conf

        user  root;

        ......

socket() failed (13: Permission denied) while connecting to upstream的相关教程结束。