Web Servers

• Web server software is a product that works with the operating system • The server computer can run more than one software product such as e-mail and FTP • With both a LAN and the Web, controlling access is very important • The Web server can be part of the LAN • Web communication and LAN communication are different

Web Server Platforms Microsoft

• Windows NT (IIS 4) – IIS (Internet Information Server) was added in the mid-1990s, and support for ASP was added later • Windows 2000 (IIS 5) – IIS part of the OS from the beginning – .NET Framework add-on allows use of ASP.NET

• Windows Server 2003 (IIS 6) – .NET Framework integrated into OS

Other Microsoft Server Products

• Application Center – Allows you to manage a cluster of servers as if it is one server • Biztalk Server – Connects to your business partners using XML • Commerce Server – Builds e-commerce sites in a short amount of time

Other Microsoft Server Products

• Internet Security and Acceleration Server – Combines a firewall product with a Web cache • Operations Manager – Helps decrease support costs for a server environment • SharePoint Portal Server – Set up a site that is highly personalized

Configuring TCP/IP in Windows

• To determine TCP/IP configuration, type

ipconfig

at a command prompt

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: 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

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 18:21:25 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 e-mail 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

File System Permissions

• Permission allow you to control access to the resources on a computer such as a Web page, a document, or a program • In Windows, the NTFS file system is required in order to assign permissions • All Linux file systems incorporate permissions

File System Permissions in Windows

Permission

Full Control Modify Read

Description

Full Control includes all other permissions and allows you to take ownership of the file or folder and change the attributes of a file Allows read, write, and delete With this permission, you can read files but cannot execute them Write Read & Execute List Folder Contents When set on a file, this permission allows you to write to files; when set on a folder, you can write to the folder Read files and run programs This permission allows you to view the contents of a folder Special Permissions (Windows 2003 only) This is not a specific permission; under the list of permissions for users, when this permission is checked, it means that this user has one or more of the 14 individual permissions set

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 8080 • www.technowidgets.com:8080/prod.htm

• Because it requires a user to add the port number, it is not a popular method

UNIX/Linux

• UNIX was introduced in 1969 • Linux is from the early 1990s – Based on MINIX • Three basic components – Kernel – central portion of OS – File system – provides input and output mechanisms – Shell – provides user interface

Linux

• Source code is freely available – Developers can make changes • Available from a number of organizations – Red Hat – Mandrake – SuSe

Summary

• Server administration focuses on LANs • Web server administration focuses on the Internet • Both types of administrators install, configure, and maintain servers • Many pieces make up the network • There are many Web server platforms from which to choose

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