Web Server Administration

1
Web Server Administration

• Chapter 6
• Configuring a Web Server

2
Overview

• Understand how a Web server works
• Install IIS and Apache Web servers
• Examine the IIS and Apache properties
• Host multiple Web sites
• Configure new Web sites in IIS and Apache
• Understand virtual directories

3
How a Web Server Works

• HTTP (Hypertext Transfer Protocol) defines how
  information is passed between a browser and a Web
  server
• The two most popular Web servers are
• Apache from Apache Software Foundation
• Internet Information Services (IIS) from
  Microsoft
• The original Web server from Microsoft available
  on Windows NT was Internet Information Server
• Almost two-thirds of all Web servers use Apache

4
How a Web Server Works

• As is true with other servers such as DNS, Web
  servers listen for communication at a port
• The default port is 80
• You can also create Web servers at port numbers
  greater than 1023
• Each Web server has a root, which is where you
  store the HTML documents

5
Understanding HTTP

• The current version of HTTP is 1.1
• Virtually no browsers are so old that they do not
  support 1.1
• HTTP is a stateless protocol, meaning that each
  Web page sent is independent of every other Web
  page sent
• This makes it more challenging to create a
  shopping cart application

6
Understanding HTTP

• HTTP 1.1 supports persistent connections
• This allows the browser to receive multiple files
  in one TCP connection
• This can speed up communication
• Although you see a single page in your browser,
  it can be composed of many text and image files

7
Understanding HTTP

• When the browser sends a request to a Web server,
  it looks like
• GET /hello.htm HTTP/1.1
• Host www.technowidgets.com
• The above requests the hello.htm file from the
  root of the Web server
• It specifies the host of www.technowidgets.com
• There could be multiple hosts at the IP address

8
Understanding HTTP

• The following shows some of the headers along
  with the HTML that the Web server would send
• HTTP/1.1 200 OK
• Server Microsoft-IIS/5.0
• Content-Type text/html
• Last-Modified Fri, 17 May 2005 182125 GMT
• Content-Length 43
• lthtmlgtltbodygt
• Hello, World
• lt/bodygtlt/htmlgt
• The headers contain information about the page

9
Features in Apache

• Apache 1.3 was used for many years but version
  2.0 was released in 2001
• Apache can also be used as a proxy server
• A proxy server isolates your real Web server from
  the Internet
• Apache 2.0 has
• Better support for Windows
• Support for IPv6
• Simplified configuration
• Unicode support in Windows
• Multilanguage error responses
• Apache supports many programming languages such
  as Perl and PHP

10
Features in IIS

• IIS versions associated with Windows versions
• Windows NT IIS 4.0
• Windows 2000 IIS 5.0
• Windows Server 2003 IIS 6.0
• SMTP can be easily added so you can send e-mail
  from your Web pages

11
Features in IIS 5.0

• Web Distributed Authoring and Versioning (WebDAV)
• Allows a server to share Web-based files
• Named virtual hosting
• Multiple Web sites can share a single IP address
• Per Web site bandwidth throttling
• Control bandwidth by Web site
• Kerberos authentication
• Secure Sockets Layer 3.0
• Encrypted communication

12
Features in IIS 6.0

• Increased security
• Default permits only HTML documents
• Expanded language support
• Can use XML and SOAP
• Support for IPv6
• Increased dependability
• Kernel-mode HTTP service
• Self-healing mechanism

13
Components in IIS

• File Transfer Protocol (FTP) server
• To transfer files between user and server
• FrontPage 2000 Server Extensions
• Used by programs to transfer files to and from a
  Web site
• NNTP Service
• Used to create user forums
• SMTP Service
• World Wide Web Server

14
Installing Apache

• Apache can be installed when you install Linux
• It is also on Red Hat CD 2
• If you install it from the Red Hat CD, the
  directories will be consistent with other server
  applications
• If you download it from the Apache Web site, you
  have to compile it and install it

15
Starting Apache

• By default, Apache does not start after you
  install it
• The following table has a list of commands

Procedure Command
Start Apache apachectl start
Stop Apache apachectl stop
Restart Apache apachectl restart
16
Minimal Apache Configuration

• Add a ServerName in /etc/httpd/conf/httpd.conf
• Add apachectl start to /etc/rc.d/rc.local

17
Default Web Site Properties in IIS
18
Tabs on the Default Web Site Properties Dialog Box

• Operators (Windows 2000) only
• This property lists users who can administer Web
  site
• Performance
• Limit bandwidth by Web site
• Limit simultaneous connections (Windows 2003)
• ISAPI Filters
• Specify applications that process HTTP requests

19
Tabs on the Default Web Site Properties Dialog Box

• Home Directory
• Specifies the location and properties of the root
• Log information here
• Permissions
• Documents
• Configure the name for default Web pages
• HTTP Headers
• Add your own custom headers
• Custom Errors
• Create custom pages for HTTP errors

20
Apache Properties-Global Environment

• ServerRoot
• Directory location of server files
• KeepAlive
• Indicates whether Apache should maintain a
  persistent connection
• Listen
• Determines the port number for the server
• Default is 80

21
Apache Properties-Main Server Configuration

• User
• Shows the user name that Apache employs when
  someone requests a Web page
• The default is apache
• ServerAdmin
• E-mail address of administrator
• ServerName
• DNS host name or IP address of server
• DocumentRoot
• Directory where the Web pages are stored

22
Hosting Multiple Web Sitesby Port Number

• Associate each new Web site with a port above
  1023
• To retrieve a Web page from a site at port 8080
• www.technowidgets.com8080/prod.htm
• Because it requires a user to add the port
  number, it is not a popular method

23
Hosting Multiple Web Sitesby IP Address

• You can create multiple IP addresses on a single
  NIC
• Referred to as virtual IP addresses
• Useful for flexibility because if each domain has
  its own unique IP address, you can easily move
  the domain to a different Web server
• It is getting more expensive to get multiple IP
  addresses from an ISP

24
Hosting Multiple Web Sitesby Host Name

• Multiple host names can be associated with a
  single IP address
• Getting a single IP address from your ISP is
  relatively inexpensive
• You can host an almost unlimited number of
  domains with a single IP address
• It is the most common method of hosting

25
Configuring a Virtual Host Based on an IP Address
in Apache

• In /etc/rc.d/rc.local, add an IP address such as
• /bin/ifconfig eth00 192.168.0.150
• In the Virtual Host section of httpd.conf
• ltVirtualHost 192.168.0.150gtServerName
  research.technowidgets.comDocumentRoot
  /var/www/researchlt/VirtualHostgt

26
Configuring a Virtual Host Based on a Host Name
in Apache

• NameVirtualHost defines the common IP address
• Multiple configurations repeat the same IP
  address and define unique ServerName settings
• NameVirtualHost 192.168.0.100
• ltVirtualHost 192.168.0.100gt
• ServerName www.technowidgets.comDocumentRoot
  /var/www/htmllt/VirtualHostgt ltVirtualHost
  192.168.0.100gtServerName web1.technowidgets.comD
  ocumentRoot /var/www/web1lt/VirtualHostgt

27
Configuring a Virtual Directory in Apache

• The following associates the virtual directory
  called prod with the location of the directory
• Alias /prod/ /var/www/prod/
• Then it configures the directory
• ltDirectory /var/www/prodgt AllowOverride
  None Order allow, deny Allow from all
• lt/Directorygt

28
Summary

• Web servers use HTTP to send HTML documents
• IIS is from Microsoft while Apache is from Apache
  Software Foundation
• IIS modifications are made through property pages
• Apache modifications are typically made by
  changing /etc/httpd/conf/httpd.conf

29
Summary

• You can create multiple Web sites on a single
  computer by adding port numbers, IP addresses,
  and/or host names
• Virtual directories are directories that appear
  to be located beneath the root, yet are
  physically located elsewhere