Web TechnologyWeb Server Setup

Course Overview and Goals

• This course will teach you how to install, configure, and administer a Web server that runs on a Unix system and can be used to deliver dynamic content.

What This Course Is and Is Not

• The purpose of the course is to teach you how to setup a Web server. This means you will be learning how to use tools to deliver content for the World Wide Web, not to create content.

World Wide Web Unix Administrator Certificate

• This course is one of four required to receive the World Wide Web Unix Administrator Certificate.

Prerequisites

• Familiarity with a Web browser such as Netscape or Internet Explorer.

• You should have user-level experience with UNIX and must be familiar with the use of a UNIX text editor like vi, emacs and pico.

• Some level of experience with creating HTML documents may be helpful.

Course Resources

• Textbook: Professional Apache by Peter Wainwright (Wrox Press, 1999).

• User account on Linux server iti.rutgers.edu.

How does the World Wide Web Work?

• Works on a client/server model. The Web server is the server component. The Web browser is the client component. Purpose of the Web server is to provide documents to clients.

• Web servers, Web browsers, and the information that is shared between them through the Hypertext Transfer Protocol (HTTP) protocol make up the World Wide Web.

History of the World Wide Web

• Grew out of the Internet, a network of networks designed that began in the early 1970’s and was used to support a variety of services (including telnet, ftp, Usenet, email, and gopher) that communicated via TCP/IP (Transmission Control Protocol/Internet Protocol).

• In 1989, Tim Berners-Lee at CERN developed a new system to simplify document distribution and to allow documents to be linked together. Called the “WorldWideWeb.”

Web History, con’t.

• In 1993, the National Center for Supercomputing Applications (NSCA) released to the public a NCSA server software and a GUI Web browser called Mosaic. Quickly became popular.

• Mosaic became Netscape

Who is a Webmaster?

• A Webmaster is someone responsible for the content and/or management of a Web site and/or a Web server.

What Roles Do Webmasters Play?

• Web Designers – Create graphical elements and determine layout of Website.

• Content Providers- Create and edit HTML documents.

• Web Developers – Write CGI, Java, JavaScript, ASP, PHP, and other scripts or programs that are used to deliver dynamic content.

Webmaster Roles, con’t.

• Administrators – Responsible for maintaining the Web server software and often the operating system and hardware where the Web server is installed.

• For most organizations, these responsibilities tend to be split over multiple job positions except for very small and simple Web sites.

Planning Your Server

• How and where will you host it? • What kind of hardware will you use? • What kind of Operating System will the hardware

run? • What Web server software will you use? • What domain name will your site use? • Answers to above questions usually determined by

budget, staffing, and existing infrastructure of your organization.

Hosting Your Server: Use an ISP (Internet Service Provider)• Free Page Site – For personal use, limited space

and tools, adds advertisements. (examples: Yahoo, Tripod, Xoom, etc.)

• Personal Page Site – For personal use, usually included with dialup account (about $20 per month), 2-20 MB disk space, none or limited access to server-based technologies for delivering dynamic content, generally under your ISP’s domain. (Website URL usually looks something like: http://www.yourisp.com/~yourusername)

Hosting Your Server, con’t.• Virtual Host – For business or personal use, share a

machine with other domains, can use your own domain (http://www.yourdomain.com), should provide a fairly wide range of tools for building more complex Websites, costs based on disk usage and traffic, ranges from $10 to several hundreds of dollars a month. Generally available through all ISPs and Hosting-only providors such as Highway Technologies (http://www.hway.net) and YourDomainHost (http://www.yourdomainhost.com)

Hosting Your Server, con’t.

• Dedicated Server – For business use, ISP owns and runs the machine, your organization dictates the configuration and has exclusive access to the system, expensive.

• Co-Located Server – For business use, your organization owns the hardware and software and is responsible for maintaining it, ISP houses the system and provides a network connection, pricing determined by bandwidth requirements.

Hosting Your Server: Do It Yourself: Networking Options

• For an Intranet Server– Need a LAN (local area network).

• For an Internet Server – Need a dedicated Internet connection. Internet Connectivity Options: – POTS (up to 56Kbps) – not practical for business use – ISDN (128Kbps) – only a good choice if cable or DSL is

not available – Cable (512Kbps – 10Mbps) – DSL (128kps – 1.54 Mbps+) – T-1 (up to 1.54Mbps) – full, fractional, or burstable – T-3 (up to 45 Mbps)

Finding an ISP

• Setting up a Internet Web site will require you to purchase some level of services from an ISP.

• The List – http://thelist.com

Hosting Your Server: Hardware Options

• Need to select a machine architecture (i.e Intel Compatible PC, Sun, Macintosh G4).

• Processor speed and number of processors.

• RAM and Disk Space.

• NIC card.

• Price can range from several hundred dollars to thousands of dollars.

Hosting Your Server: Operating System Options

• Commercial Versions of Unix (i.e. Solaris, Irix, HP-UX, AIX, MacOS X).

• Free Versions of Unix (i.e. Linux, FreeBSD). • Microsoft Windows (9x, NT, Windows 2000). • Novell NetWare • Windows vs. Unix – raises issues of easy of use,

stability, scalability, open source, and pricing.

Hosting Your Server: Web Server Software Options

• According to the Netcraft Web Server Survey (http://www.netcraft.com), as of January 2000, three Web server software distributions support over 90% of all Web servers on the Internet: – Apache 61.66% – Microsoft Internet Information Server 19.63% – Netscape Enterprise 7.22%

Web Server Software Options: Apache

• “The standard” for UNIX web servers.

• Originally based on NCSA httpd code.

• Can be installed under most Unix variants and Windows. Binary versions available for many operating systems.

• Uses file-based configuration, although GUI tools are also available.

Introduction to Apache, con’t.

• Unix versions very stable. Windows version less mature (beta-level code).

• Very Fast and uses resources efficiently. • Freely distributed source code. Can be modified

for commercial or non-commercial use. • Price: Free • See http://www.apache.org for more information.

Web Server Software Options: Netscape Server

• Sometimes referred to as the iPlanet server• Distributed through Sun-Netscape Alliance called

iPlanet. • Server packages: iPlanet/Netscape Enterprise

Server, Netscape Fast-Track Server. • Runs under Windows NT, Solaris, Irix, HP-UX,

Digital Unix, AIX, Linux (coming soon).

Netscape iPlanet Server, con’t.

• Uses Web-based administration.

• Can be resource intensive.

• Price: $1495 per processor for Enterprise Server

• See http://www.iplanet.com/products/infrastructure/web_servers for more information.

Web Server Software Options: Microsoft Internet Information

Server• Most popular for NT-based web servers.

• Runs only under Windows NT Server. IIS v4 is the most popular release. IIS v5 was released with Windows 2000 Server.

• GUI-based administration. Web-based administration available as well.

• May not scale well.

Microsoft IIS, con’t.

• Source code not available. Extendable through Microsoft’s Internet Server API (ISAPI).

• Price: Free with NT Server 4.0

• See http://www.microsoft.com/ntserver/web/default.asp for more information.

Important Notes about Web Server Hardware

• Web Servers need fast disk access and a lot of RAM to handle high-volumes of traffic.– Not unusual to see web servers with 1GB of

RAM and 10,000RPM hard drives.

• Processor speed and performance becomes very important when delivering dynamic content via CGI scripts, Server Side Includes or other web applications.

How the Internet Works: Networking Basics

• For a Web server to be useful it will need to be attached to a network.

• Minimum requirements for a computer network – at least two computers that have a media and a method of communicating.

• All Internet applications use TCP/IP (Transmission Control Protocol/Internet Protocol) for low-level communications.

Networking Basics: TCP/IP

• TCP/IP is actually a combination of 2 protocols:

• A transport layer protocol called the Transmission Control Protocol (TCP)

• A network protocol called the Internet Protocol (IP)

Networking Basics: IP Addresses• TCP/IP uses IP address to identify different

devices. Every computer on the Internet must have a least one unique IP address.

• IPv4: IP address are four 8-bit numbers separated by dots: 165.230.30.68 – Usually divided in three parts: – 165.230 is one of Rutgers’ networks – e.g. no one else has

addresses starting with 165.230– 30 is the subnet portion of the address– 68 is the particular node, or host portion of the address

• Division not necessarily on octet boundary.

TCP/IP: Two Friends, Working Together

• IP - An IP address represents a machine’s identity on the internet and tells other machines how to get to it – similar to your street address (e.g. 123 Main Street, Anytown, USA).

• TCP is a mechanism used to ensure that anything sent to a specific IP address makes it there in one piece. – similar to the Post Office.

• Together, TCP/IP assures that anything sent to a server on the Internet is delivered to the right place in one complete piece.

Networking Basics: IP Addresses

• IP addresses no longer being distributed by classes – blocks are distributed to ISPs on an as-needed basis and must be justified.

• IP addresses are hard to come by. How do you get them? – Your ISP received an “address space” from the ARIN

(http://www.arin.org)

– You receive IP addresses from your ISP.

Networking Basics: Tools

• Network interfaces need to be assigned IP addresses.

• Interfaces can be configured using ifconfig command on UNIX machines.

• Type ifconfig –a to view current configuration settings.

• Additional tools for network monitoring: ping, traceroute, tcpdump, netstat, arp, snoop.

Networking Basics: DNS• IP addresses are usually paired with more

human-friendly names: Domain Name System (DNS).

internet.rutgers.edu

Hostname Organization Top-level domain

• Other top-level domains include .com, .gov, .org, etc. There are also country-specific domains like .uk, .ca, .jp, etc.

Networking Basics: DNS, con’t.

• Domain name information is maintained through a distributed database of host name/ IP address pairing.

• The Network Information Center (NIC) manages the top-level domains, delegates authority for second-level domains, and maintains a database of registered name servers for all second-level domains.

• Host name assignments maintained through zone files on primary DNS server. Secondary DNS server gets zone file from primary server.

Networking Basics: DNS, con’t.

• Network Solutions (previously the InterNic) registers domain names – See http://www.networksolutions.com. Other registrars include Register.com

• Costs range from $20 to $50 per year.• ISP’s beginning to offer domain name

registration as part of other packages. • Need to register a primary and secondary domain

name servers for your domain and arrange to have zone files created on DNS servers.

DNS Overview: If DNS Servers Could Talk…

Networking Basics: DNS Tools

• There are several tools for for monitoring DNS information:– whois – tells you the owner and primary DNS servers

associated with a domain (e.g. whois yahoo.com). Also available via web browser at www.networksolutions.com.

– nslookup and host – tell you IP address information for a particular hostname on the internet (e.g. nslookup www.yahoo.com or host www.rutgers.edu)

DNS Exercise

• What are IP addresses of the DNS servers that contain information about rutgers.edu?

• What are the IP address of:– www.retaildecisions.com– abusaday.admin.cju.com– www.linux.org

Networking Basics: Ports• Servers tend to run a number of services. A single NIC

can be used to provide multiple services through ports. • Servers with Internet-related services listen on specific

ports. Clients contact server by specifying an IP address and a connection port.

• Common services and port numbers: – smtp 25, ftp 21, telnet 23, http/web 80, https/ssl 443– A list of services and ports is contained in the /etc/services

file

• Ports below 1024 are reserved for system services and can only be used by programs started by root.

Web Servers and UNIX Systems• Most web servers run on port 80 – the standard

web port• Web server software usually runs on UNIX

system as some user other than root. It’s considered a security risk to run the web server software as root.

• The web server software binary is httpd. Web server software is often refered to as “the httpd”

Uniform Resource Locator (URL)

• URL: a fancy way of saying “web site address”

• Anatomy of a URL:

http://internet.rutgers.edu:80/ITI520/index.html

Protocol Hostname Port Number Path To File

HTTP – An Introduction

• HTTP – The Hypertext Transfer Protocol– The protocol used between web clients

(browsers) and web servers.– Web browsers “ask” for a specific web page

from the server, who returns the content

HTTP: Example and Exercise

• You can emulate the HTTP conversation between a browser and a server:– telnet to the internet.rutgers.edu machine, port

80, e.g. telnet internet.rutgers.edu 80 from the UNIX command line.

– Type: “GET HTTP/1.0 /” Press Enter twice.– The server returns the HTML (web page code),

which is usually interpreted and displayed by your web browser.

Unix Tools and Commands• File Editors: vi, emacs, pico • File system navigation: cd • File management: mv, rm, mkdir,rmdir, ls,

chmod, ln • Archiving and compression: tar, gzip• ***Process management: ps, kill • Man pages available for all these

commands, e.g “man rmdir”

UNIX Process Management• UNIX Processes are managed using the ps

and kill commands– ps is used to list processes running on the

system– kill is used to kill and restart processes running

on the system

• Every time you start a new program (pico, vi, bash, etc.) a process is created and you are the owner of that process.

Process Management Exercises

• You can type ps –aux to see all the processes running on a system. This will list the process owner, process ID (PID) and the command being run.

• You can kill any PID, as long as you are the owner of the process.

• ps –u shows all the processes your are currently running

Process Management Exercises, con’t.

• Open up a new terminal window and type vi foo.txt. This will create a new process on the system that you own.

• Switch back to your original terminal window. Locate the process ID for your vi session and kill it.