现象：

• 网站无法打开
• 可以ping通

调试过程：

• ssh登录网站
• sudo service apache2 restart 返回信息：

* Restarting web server apache2

(98)Address already in use: make_sock: could not bind to address 0.0.0.0:80

no listening sockets available, shutting down

Unable to open logs

Action ‘start’ failed.

The Apache error log may have more information.

[fail]

$ sudo netstat -ltnp | grep ':80'

tcp 0 0 127.0.0.1:8005 0.0.0.0:* LISTEN 1534/java

tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 20658/apache2

tcp 0 0 0.0.0.0:8080 0.0.0.0:* LISTEN 1534/java

$ sudo kill -9 20658

$ sudo service apache2 restart

Done.