Web Server Administration Chapter 6 Configuring a Web Server

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

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

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

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

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

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

Understanding HTTP The following shows some of the headers along with the HTML that the Web server would send: HTTP/ OK Server: Microsoft-IIS/5.0 Content-Type: text/html Last-Modified: Fri, 17 May :21:25 GMT Content-Length: 43 Hello, World The headers contain information about the page

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

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 from your Web pages

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

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

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

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

Starting Apache By default, Apache does not start after you install it The following table has a list of commands ProcedureCommand Start Apache apachectl start Stop Apache apachectl stop Restart Apache apachectl restart

Minimal Apache Configuration Add a ServerName in /etc/httpd/conf/httpd.conf Add apachectl start to /etc/rc.d/rc.local

Default Web Site Properties in IIS

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

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

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

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

Hosting Multiple Web Sites by Port Number Associate each new Web site with a port above 1023 To retrieve a Web page from a site at port Because it requires a user to add the port number, it is not a popular method

Hosting Multiple Web Sites by 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

Hosting Multiple Web Sites by 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

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 eth0: In the Virtual Host section of httpd.conf ServerName research.technowidgets.com DocumentRoot /var/www/research

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 ServerName DocumentRoot /var/www/html ServerName web1.technowidgets.com DocumentRoot /var/www/web1

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 AllowOverride None Order allow, deny Allow from all

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

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