200 - OK，服务器成功返回网页
- Standard response for successful HTTPrequests.
301 - MovedPermanently（永久跳转），请求的网页已永久跳转到新位置。
- This and all future requests should bedirected to the given.
403 - Forbidden（禁止访问）,服务器拒绝请求
- forbiddenrequest (matches a deny filter) => HTTP 403
- The requestwas a legal request, but the server is refusing to respond to it.
404 - Not Found,服务器找不到请求的页面。
- The requested resource could not be foundbut may be available again in the future.
500 - InternalServer Error（内部服务器错误）
- internal error in haproxy => HTTP 500
- A generic error message, given when nomore specific message is suitable.
502 - Bad Gateway（坏的网关）,一般是网关服务器请求后端服务时，后端服务没有按照http协议正确返回结果。
- the server returned an invalid orincomplete response => HTTP 502
- The server was acting as a gateway orproxy and received an invalid response from the upstream server.
503 - ServiceUnavailable（服务当前不可用）,可能因为超载或停机维护。
- no server was available to handle therequest => HTTP 503
- The server is currently unavailable(because it is overloaded or down for maintenance).
504 - GatewayTimeout（网关超时）,一般是网关服务器请求后端服务时，后端服务没有在特定的时间内完成服务。
- the server failed to reply in time =>HTTP 504
- The server was acting as a gateway or proxy and didnot receive a timely response from the upstream server.
原因1：
Apache的配置文件中没有对站点目录的权限许可配置，这通常是在初始化安装apache后，更改了默认的apache站点目录所致；
<Directory "/application/apache2.2.26/htdocs">
Options Indexes FollowSymLinks
AllowOverride None
Order allow,deny
Allow from all
</Directory>
<Directory"/var/blog/">
Options FollowSymLinks
AllowOverride None
Order allow,deny
Allow from all
</Directory>
这个可以在httpd-vhosts.conf中配置，主配置文件就是全局的配置；
原因2：
站点目录下没有首页文件（index文件），而apache的配置又禁止了目录浏览，就会提示403错误；
也就是把Options IndexesFollowSymLinks中有的Indexes文件；然后站点目录下又没有index.html文件；就会把站点目录下的目录结果都在浏览器上显示；如果把索引禁掉Indexes，则就会报403错误；
原因三：还是Directory权限问题：
<Directory "/application/apache2.2.26/htdocs">
Options Indexes FollowSymLinks
AllowOverride None
Order allow,deny
Allow from all
Allow from 10.0.0.0/24
deny from 192.168.0.0/24
</Directory>
原因四：站点目录权限问题；
站点目录需要有apache的用户有访问权限，否则就会报403错误；
[[email protected]]#ll /var/blog/
total 6968
-rw-r--r-- 1 ettett 54724 Jun 12 2011 expires.jpg
-rw-r--r-- 1 ettett 54724 Jun 12 2011 expires.jpg.1
-rw-r--r-- 1 ettett 49 Dec 12 23:01 index.html
-rw-r--r-- 1 ettett 418 Sep 25 08:18 index.php
-rw-r--r-- 1 ettett 19929 Jan 18 2013 license.txt
-rw-r--r-- 1 ettett 6586 Dec 13 15:26 readme.html
-rw-r--r-- 1 ettett 316 Dec 20 18:30 test_mysql.php
drwxr-xr-x 2 ettett 4096 Dec 20 18:53 wordpress
[[email protected]]#egrep "User|Group" httpd.conf
# User/Group: Thename (or #number) of the user/group to run httpd as.
User ett
Group ett
LogFormat "%h%l %u %t \"%r\" %>s %b \"%{Referer}i\"\"%{User-Agent}i\"" combined
LogFormat "%h%l %u %t \"%r\" %>s %b \"%{Referer}i\"\"%{User-Agent}i\" %I %O" combinedio
# User homedirectories
[[email protected]]#pwd
/application/apache/conf