502 Bad Gateway（Nginx） 查看nginx日志有如下内容
2016/09/01 09:49:41 [error] 79464#79464: *3 user "nagios" was not found in "/usr/local/nagios/etc/htpasswd.users", client: 192.168.1.209, server: localhost, request: "GET / HTTP/1.1", host: "192.168.1.5"
2016/09/01 09:49:45 [error] 79464#79464: *3 user "nagios" was not found in "/usr/local/nagios/etc/htpasswd.users", client: 192.168.1.209, server: localhost, request: "GET / HTTP/1.1", host: "192.168.1.5"
2016/09/01 09:49:51 [crit] 79464#79464: *3 connect() to unix:/tmp/phpfpm.sock failed (13: Permission denied) while connecting to upstream, client: 192.168.1.209, server: localhost, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/tmp/phpfpm.sock:", host: "192.168.1.5"
2016/09/01 09:49:51 [error] 79464#79464: *3 open() "/usr/local/nagios/share/favicon.ico" failed (2: No such file or directory), client: 192.168.1.209, server: localhost, request: "GET /favicon.ico HTTP/1.1", host: "192.168.1.5"
2016/09/01 09:49:51 [error] 79464#79464: *3 open() "/usr/local/nagios/share/favicon.ico" failed (2: No such file or directory), client: 192.168.1.209, server: localhost, request: "GET /favicon.ico HTTP/1.1", host: "192.168.1.5"
前面两个是因为密码不对
第二个说是connect() to unix:/tmp/phpfpm.sock failed 重点是：(13: Permission denied)
后面的错误是因为受到[crit]的影响而来的
这里呢，上次碰到过一次，不过也弄了好久，
这一次有点印象，就很容易找到原因，并且修改回来
开始修改文件了--------------------------
[root@dep5 ~]# vim /usr/local/php/etc/php-fpm.conf
查找phpfpm.sock这一向，发现这个sock在/tmp下面，
[root@dep5 ~]# ll /tmp/phpfpm.sock
srw-rw---- 1 root root 0 9月 1 08:30 /tmp/phpfpm.sock
发现phpfpm.scok的属主属组都是root用户，并且权限为660
而且源码安装PHP和Nginx指定的用户是daemon，daemon，根本没权限查看和修改这个sock文件
解决一方案：
vim /usr/local/php/etc/php-fpm.conf
查找下面那两个
; Set permissions for unix socket, if one is used. In Linux, read/write
; permissions must be set in order to allow connections from a web server. Many
; BSD-derived systems allow connections regardless of permissions.
; Default Values: user and group are set as the running user
; mode is set to 0660
listen.owner=****
listen.group=****
将那listen.owner和listen.group注释取消掉，并且改成nginx用户
或者
将 ;listen.mode = 0660 注释取消的，直接改成777得了（^_^）
解决方案二：
chmod 777 /tmp/phpfpm.sock
#PS：我没试过这个方案，但觉得可行，但是这里还有个问题，当把php-fpm重启的时候，权限又被自己改回来了，。。。。。
