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To edit and update your page with the current news of the day, just fire up OpenOffice.org Writer and open your document. Make your changes and save the file, and your local network site is automatically updated.

Taking Your Site Public with Dynamic DNS

You can make your Web site public by renting server space from an ISP or by obtaining your own domain name and hosting the site from your Apache server. When you rent machine space from an ISP, you pay not only for the room your data takes up, but also for the Web traffic to your site. If you have a small and simple site with little traffic, that’s not a problem. If you have a large or complex site with a lot of traffic, renting server space can get costly.

You can save time and money by running high-maintenance Web sites on local machines. If you use PHP to build your site or have live database access from the site, keeping the data where it can be updated easily is a real timesaver.

In order for others to find your Web site, you have to have a host name, and the host name must be fully qualified — that is, your host name must include a domain name (something like www.example.com). If your ISP is willing to assign you a fully qualified host name, you’re good to go. If not, don’t despair — you can borrow someone’s domain name by using dynamic DNS.

Understanding how dynamic DNS works

When a user surfs to your spanking new Web site, he types a name (say www.example.com). His Web browser asks a name server to convert the site name into an IP address. His local name server defers the request to a well-known name server somewhere on the Internet. Eventually, the name server chain locates a

server that’s responsible for the example.com domain. That name server returns the IP address for host www (that is, host www within the example.com domain).

A normal name server maintains a database that converts host names into IP addresses for the hosts on the name server’s local network. A dynamic DNS server provides the same service (host name to IP address translation), but it lets you change the database. To use a dynamic DNS server, you send your IP address and desired host name to the server, and it agrees to give out your IP address whenever someone asks for your fully qualified host name. Of course, the domain name that you get to use is owned by the dynamic DNS provider, but it gives you a permanent, fully qualified name that you can hand out to friends and business partners (without purchasing a domain name for yourself).

What happens if your Internet service provider changes your IP address? Simple — just update the dynamic DNS database.

Setting up dynamic DNS

To use dynamic DNS, you first contact a company (often an ISP) that will register your site name. You can find quite a few free (and paid) dynamic DNS providers online.

Each service provider has its own how-to’s for setting up a dynamic DNS service. The basics are pretty much the same, but read the FAQs for each service online before registering an account with that service.

One dynamic DNS service worthy of mention is DynDNS.org. Follow the simple how-to page at www.dyndns.org/services/dyndns/howto.html to set up your dynamic DNS account in no time. Follow the links to do the following:

1. Register for an account.

You’ll receive an e-mail confirming the account registration.

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2. Confirm the account registration to activate the account.

3. Add host information for your computer:

Choose a host name and an extension. Our personal favorite has to be is-a-geek.com.

The DynDNS service automatically detects and fills in the IP Address field.

Select the Wildcard check box if you want your name to be accessible from both www.sitename.dyndns.com and sitename.dyndns.com.

4. Click the Add Host button, and you’re done.

If your Apache server is running and your firewall is allowing access through port 80, your Web site should be exposed to the Web.

The exposure you get through the Web is also a liability. Build a good, sturdy firewall to protect the rest of your system — see Technique 34 for more information about firewalls.

Better yet, keep your site in a UML jail. Visit Technique 58 for information about installing Apache in a UML jail with ADIOS.

Updating your IP address

Different ISPs have different policies about changing the IP address of your local network. If you’re connected to the Internet using a dial-up account, your IP address changes each time you connect. Other connection types may assign you a semi-permanent IP address or change your address every few days. If your ISP changes your IP address only when you log out, you need to update the dynamic DNS host information only when you’ve logged out and back in again. If your IP address changes more often, you’ll probably want to use a client program to monitor the changes and update the host information for you.

You can also update the host information manually by visiting your account information at DynDNS. Choose your host from the list of hosts that you manage, and its server will detect your address. If your address has changed, click the Modify Host button to update the information.

Be sensitive to the fact that updating your IP address when it hasn’t changed will invoke the ire of the good people at DynDNS. Compare IP addresses and update your account only if the IP address has changed. Otherwise, your service will be interrupted for abusing your privileges.

Technique 45 is all about creating a self-signed SSL certificate for your Apache Web site. Check it out!

Keeping Your Apache Server

Up-to-Date the Easy Way

If you run an Apache server for any length of time, you’ll probably find it needs a bit of tweaking. You may want to enable new features or add virtual hosts (whole new Web sites) to your servers. You can make those changes directly with a text editor and the Apache configuration file, but you can save time by configuring your server with a good graphical tool.

Fedora Linux comes with a very friendly configuration tool that makes it easy to manage your Apache server: It’s called the HTTP Configuration tool, and we show you how to install and use it in this section. If you’re using a distribution other than Fedora

(say, Mandrake or SuSE), we recommend that you get familiar with Webmin’s Apache configuration module — it’s not as friendly as Fedora’s tool, but it’s better than editing configuration files by hand. See Technique 17 for more information about Webmin.

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Fedora’s HTTP Configuration tool is an easy-to-use, graphical interface that allows you to access many of the Apache configuration options with just a few mouse clicks. For simple configuration changes, or complex virtual host setups, it’s great.

Installing the Fedora HTTP Configuration tool

The Fedora HTTP Configuration tool is not installed by default with a standard Fedora installation, but it is included on the Fedora distribution media. So you can have it up and running in no time.

To install the HTTP Configuration tool, follow these steps:

1. Open the terminal window and give yourself superuser privileges with the su command.

2. Mount your Fedora media and move into the directory containing the RPM packages.

3. Enter the following command:

#rpm -Uhv redhat-config-httpd- 1.1.0-5.noarch.rpm

With a few whirrs and clicks, the package installs.

Putting the HTTP Configuration tool to work

After you install the HTTP Configuration tool, it’s ready to use. Follow these steps to open the HTTP Configuration tool:

1. Open the Main Menu and choose System Settings Server Settings HTTP.

A dialog opens, prompting you for the root password.

2. Enter the password and click OK.

The HTTP Configuration tool opens, as shown in Figure 42-9.

• Figure 42-9: The HTTP Configuration tool.

The tool features four tabs, each controlling a different aspect of the Apache service:

Main: The Main tab controls the basic setup of the server. Use this tab to specify the server name and the Webmaster’s e-mail address, and to add or change the IP address(es) that Apache listens to. Click the Edit button to edit the IP address and port information (see Figure 42-10).

• Figure 42-10: Edit the address for your Apache server.

If you have multiple network interface cards on your system, each card has a unique IP address (and, probably, a unique host name). Specify which card Apache should service by selecting the Address radio button and entering the address of the preferred card.

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Virtual Hosts: Choose the Virtual Hosts tab to add or edit information about virtual hosts residing on your Apache server. Your Apache server can host multiple Web sites. Each virtual Web site has its own set of properties defining its name, where its root directory resides, and security information for that site.

Click Edit to open the Properties window for existing hosts, or click Add to create additional hosts.

Click the General Options entry in the left frame to open the Basic Setup menu. Use the Basic Setup menu to enter information about the name and location of the Web site files, as well as the Webmaster’s e-mail address.

Use the Site Configuration menu to edit the directory name list and error pages that display for the virtual host.

Click the SSL entry in the left frame of the Virtual Host Properties window to edit the SSL certificate information for the virtual host. If you choose to enable SSL certification, enter the location of the certificates on this menu.

Use the Logging menu to control the transfer logs and error logs for the virtual host.

Adding a reverse DNS lookup to the error log shows you who generates errors, but it also slows down your server. Gain a bit of speed by changing the drop-down list to read No Reverse Lookup.

Use the Environment Variables and Directories menus for advanced management of scripts and directories.

Server: Choose the Server tab on the HTTP Configuration tool to edit user and group ownership information and set the file locations for the process ID, lock file, and core dump directory.

Performance Tuning: Choose the Performance Tuning tab to set the number of connections allowed to the Apache server, and the connection timeout information.

The HTTP Configuration tool manipulates variables in the Apache configuration file. You can edit the configuration file directly with your favorite editor, but if you’re trying to keep life simple, the HTTP Configuration tool is about as quick as it can get.

The configuration file for your Apache server is located at /etc/httpd/conf/httpd.conf. You need superuser privileges to make changes to this file.

We recommend that you make a copy of the configuration file before making any changes to the original. It’s always good to have something to fall back on.

43 Keeping an Eye

on Your Servers

Technique

Save Time By

Using apachetop to monitor your Apache server

Using the MySQL Control Center to monitor and maintain your MySQL server

Using mtop to audit your MySQL statistics at the command line

When you expose a server to others, you need to be able to monitor the server traffic and statistics. With good monitoring tools, you can find the slowdowns and tailor the server’s responses to

your users’ needs.

apachetop is a handy, open-source monitoring tool designed specifically to return information about an Apache Web server. It’s similar in nature to top, running at the command line, and it displays statistics about your server and the users who are visiting it. apachetop is easy to install and use, and although it doesn’t go all out with bells and whistles, it returns a good amount of information. You can use apachetop to monitor not only the visitors to your server, but also your server speed as it serves up the resources in its repertoire.

The MySQL database server is a great tool by itself, but it’s even better with good monitoring and management tools. The MySQL Control Center (MySQLCC) is a graphical tool that lets you monitor, test, and repair the tables in your MySQL databases. You can also use the handy features of the Control Center to manage database users and supervise the database processes.

If you’re working with MySQL in a nongraphical environment, mtop is a handy tool that gathers and displays information about the traffic on your MySQL server. It’s similar to top (and apachetop), and it’s a breeze to use. Installation is a bit of a chore, but don’t worry — we help you through that.

This technique is all about using the tools to monitor and improve your servers. Whether it’s an Apache server or a MySQL server, keeping track of the vital statistics about its operation will let you make decisions that make your servers run faster and keep your users happy.