Networking: A Beginner’s Guide Fifth Edition- P77:I have run into many people over the years who have gained good even
impressive working knowledge of PCs, operating systems, applications,
and common problems and solutions. Many of these people are wizards with
desktop computers.
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Nội dung Text: Networking: A Beginner’s Guide Fifth Edition- P77
- 362 Networking: A Beginner’s Guide
3. Unzip the gz file using the following command (substitute the actual filename
of the file you downloaded):
gunzip filename.tar.gz
4. Untar the resulting .tar file with the following command (substituting the ac-
tual filename found in the directory after performing step 3; you can use the ls
command to see its name):
tar -xvf filename.tar
5. The tar command in step 4 creates a directory that has the same name as the
name and version portion of the tar file. Change to that directory, as follows
(change the command to match your downloaded version):
cd /httpd-2.2.3
6. Run the Apache configuration script by entering the following command (it
will take only a few seconds to run):
./configure
7. Now you need to prepare the binaries by compiling them. This takes two com-
mands, each of which might take several minutes to complete:
Make
make install
8. At this point, Apache is installed but not yet running. To start Apache, execute
the following command from any directory:
/usr/local/apache/bin/apachectl start
To test your Apache installation, you can use the ps command to verify that the
daemons are running:
ps -e |more
The ps command will display all running processes. Because the preceding
command pipes the output of ps -e through the more command, you might need to
press the spacebar a number of times to see all of the running processes. In the output,
you should see one or more copies of a process called httpd, which is the Apache
daemon. You might see many of these processes, because Apache usually starts a
number of them, depending on the computer on which you have installed Apache, but
this is perfectly normal.
After you’ve verified that Apache has started, you can also test it using a web
browser. Enter either of the following web addresses:
http://127.0.0.1
http://localhost
- Chapter 22: Setting Up a Linux Web Server with Apache 363
Both of these commands access any running web server on the computer on which
they are used. (Remember that the address 127.0.0.1 is always shorthand for the local
computer, as is the name localhost.)
You should also be able to access the page from another computer. Assuming that
the computer on which you installed Apache has an IP address of 209.200.155.49, the
following web address should bring up the page:
http://209.200.155.49
If you cannot access the page from a remote computer, but can on the local computer,
you should check basic IP connectivity using the PING command and typical network
troubleshooting techniques. It’s also possible that you have a firewall running on the
machine with Apache on it, and the firewall is preventing access.
Administering Apache Web Server
You will need to perform a number of basic administrative tasks on an Apache server,
not the least of which is publishing a web site onto your newly installed Apache web
server. This section briefly describes basic administrative tasks.
Stopping and Starting Apache
You use a script file called apachectl to start and stop the server. For a default Fedora
installation, the apachectl file is located in the /usr/sbin directory and takes three main
parameters: start, stop, and restart. For example, the following command will restart
the server:
/usr/sbin/apachectl restart
Changing the Apache Configuration
As mentioned earlier in this chapter, Apache is essentially controlled through text-based
configuration files, the main one of which is called httpd.conf. The httpd.conf file is
located in the /etc/httpd/conf/ directory.
The httpd.conf file works through the use of plain-text directives contained in the
file, along with the associated settings. For example, the following directive defines
where Apache is installed:
ServerRoot "/etc/httpd"
If you wanted to move the Apache installation to a different directory on your
Linux computer, you could certainly do so, but you would want to be careful to change
the ServerRoot setting before attempting to restart Apache in its new location.
NOTE For any changes to the httpd.conf file to take effect, you must restart Apache using the
apachectl restart command.
- 364 Networking: A Beginner’s Guide
The httpd.conf file is divided into three main sections:
Global environment
Main server configuration
Virtual hosts
Each of these sections contains a large number of directives that control how
Apache works.
When learning about Apache, you should spend some time studying the contents
of the httpd.conf file and reading the extensive comments included in the file. You
should also look up the various directives in the online Apache documentation
(http://httpd.apache.org/docs/), to get more information than provided by the
comments in the httpd.conf file.
Publishing Web Pages
By default (for Apache version 2), the main web site published by Apache is located in
the /var/www/html directory, and this directory is blank.
Once you are ready to publish a complete web site, you can place the files into /var/
www/html with the home page stored as index.html. The easiest way to do this is to
connect to the computer running Apache by using the FTP program, and then upload
the web site’s files, either directly to the /var/www/html directory or to a temporary
directory on the server’s hard disk. Once in the temporary directory, you can move them
to the correct location on the server itself using the mv or cp commands (these, among a
number of other useful Linux/UNIX commands, are covered in Chapter 21).
Chapter Summary
Most networking professionals will need to set up and maintain a web server in the
course of their work. All server platforms have web servers available for them. An
excellent web server that is available for just about all platforms is the Apache web
server. As you saw in this chapter, Apache is easy to install, administer, and get up and
running. If you have followed the instructions in the previous chapters and have set
up Fedora Linux on a test system, I recommend that you also follow the steps in this
chapter and set up and run Apache. Then add some files for a simple web site to it and
browse the web server first from the computer on which it’s running, and then from
another computer on the network.
This chapter was intended to get you started with the Apache web server. If this is an
area in which you wish to gain greater expertise, you will find more details in resources
devoted to Apache server. Two books in this area that might interest you are Apache Server
2.0: A Beginner’s Guide, by Kate Wrightson (McGraw-Hill/Professional, 2001) and Apache
Server 2.0: The Complete Reference, by Ryan Bloom (McGraw-Hill/Professional, 2002).
- Chapter 23
Introduction
to Virtualization
365
- 366 Networking: A Beginner’s Guide
O
ne of the most exciting areas to develop in networking over the past several
years is virtualization, which is a method of creating multiple virtual machines
on a single computer. These virtual machines operate as if they were running
on their own computer, and the computer’s actual resources—its processor, hard disk
space, network connection, and other hardware—are virtualized so that they can be
shared among the various virtual machines.
This chapter introduces virtualization. It discusses some of the main benefits
of virtualization, and then provides of an overview of Microsoft’s and VMware’s
virtualization offerings. To get you started, the chapter walks you through a VMware
Server installation, along with the setup of an Ubuntu Linux virtual machine.
Benefits of Virtualization
The ability to virtualize computers can pay rich dividends. The following are some of
the chief benefits of virtualization:
More efficient use of server resources As noted in previous chapters,
dedicating one server application per computer is the most reliable way to
provide the services, and it’s more maintainable as well. However, you often
will have server applications that don’t use that many server resources. For
instance, you may have a web server that is used by 30 to 40 people within
your organization on an occasional basis. With virtualization, however, you
can run multiple virtual machines—all completely independent from one
another—on a single server and more efficiently utilize the server’s resources.
Ability to run multiple operating systems on a single computer With
virtualization, there is a host operating system, which is the operating system
installed on the computer itself, and guest operating systems, which are the
operating systems installed within each virtual machine. So you can, for
instance, have a Windows Server 2008 host operating system installed on a
computer, and then run operating systems like Windows XP, Ubuntu Linux,
Windows Vista, or Sun Solaris within the virtual machines themselves. Or you
can have Linux installed on a computer, and then have a variety of Linux and
Windows operating systems running within virtual machines. You can even
have no host operating system, and instead install what is called a hypervisor,
which is a bare-bones operating system that just supports virtual machines.
Ease of moving virtual machines You can easily move virtual machines from
one virtual server to another, in order to better manage and balance resources
like disk space, RAM, and processor utilization.
Reduced power requirements You can reduce the energy required to run
your IT infrastructure. By consolidating servers, your power requirements are
reduced.
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