Software installed

Apache

Apache is an open-source web server software maintained by the Apache Software Foundation and the open-source community. It can be extended using modules, and is well-documented and well-supported. It is usually the de-facto standard Web server on Linux, although lately new and customized Web servers such as nginx have been becoming more popular for dynamic, high-traffic sites.

PHP

PHP is a server-side scripting language mainly used for web development. By writing PHP rather than plain HTML, developers are able to create pages that are dynamically generated by the server on the fly depending on parameters provided. The Zend PHP interpreter is open-source software, and is available as a module for multiple Web servers on Linux, Windows, BSD and other OSes.

MySQL

MySQL is an open source relational database management system (RDBMS). It is open-source software, released under the GPL and sponsored by Oracle Corporation. The software is available at no cost, although there are also some paid versions. It has widespread use in Web applications, such as WordPress and MediaWiki, and is also used by large sites such as Facebook and YouTube.

LAMP stack

Together, CentOS (Linux), Apache, MySQL and PHP form an implementation of a LAMP stack. This stack provides a consistent, portable environment for Web developers.

WordPress

WordPress is an open-source blogging platform and CMS. It is written in PHP, and uses a MySQL database for text content storage and metadata. It provides an easy-to-use user interface, and is highly extensible and customizable with a large number of user-creatable themes and plugins. WordPress powers some prominent sites such as Forbes.com, vogue.com and nationalpost.com.

Problems encountered during installation

• The systemctl command was not available, since this install of CentOS is using upstart rather than systemd.
• There was no default index page created during the install of httpd. As a result, accessing HTTP on the Centos3 VM server gave an HTTP error 403 (Access denied) – the default Apache configuration denies directory listings.
• The c6host machine was not able to access the HTTP service on centos3 because its iptables was not configured to allow inbound traffic on port 80.
• When configuring iptables on centos3, running iptables -A INPUT -p tcp –dport 80 -j ACCEPT was notsufficient.
  • The -A option appends the rule to the end of the INPUT chain, however, there was a pre-existing explicit rule rejecting all packets.

     REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject-with icmp-host-prohibited

  • To move the new rule above the reject rule, the incorrect rule had to be removed by running iptables -D INPUT -p tcp –dport 80 -j ACCEPT
  • Then, find the line numbers by running iptables -L –line-numbers

     Chain INPUT (policy ACCEPT)
     num  target     prot opt source               destination
     1    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED
     2    ACCEPT     icmp --  0.0.0.0/0            0.0.0.0/0
     3    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0
     4    ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:22
     5    REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject-with icmp-host-prohibited

  • Use iptables -I INPUT 5 -p tcp –dport 80 -j ACCEPT to insert the new rule above the existing rule 5.
  • Running iptables -L –line-numbers again gives the following output:

    Chain INPUT (policy ACCEPT)
    num  target     prot opt source               destination
    1    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED
    2    ACCEPT     icmp --  0.0.0.0/0            0.0.0.0/0
    3    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0
    4    ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:22
    5    ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           tcp dpt:80
    6    REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject-with icmp-host-prohibited

• The contents of the WordPress .tar.gz file were extracted to /root/wordpress. Moving this directory to /var/www/html resulted in the Apache process not being able to read the wordpress subdirectory. Copying (cp -R) avoids this issue.
• When configuring the WordPress connection to MySQL, the WordPress documentation said to run the query

  mysql> GRANT ALL PRIVILEGES ON databasename.* TO "wordpressusername"@"hostname"
      -> IDENTIFIED BY "password";

  to allow access to the database. However, since the MySQL server and Apache/WordPress are installed on the same host, we need to use “localhost” rather than “centos3” for the hostname.