Transcript Chapter 22

Chapter 22
Web Hosting and
Internet Servers
Xuanxuan Su
Topics
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Web
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FTP
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News
Web Hosting
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Web hosting platform
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Reliability
Maintainability
Security
Performance
Unix vs. Windows
HTTP protocol
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The foundation of the WWW
TCP-based protocol
Transmit documents
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Text
Pictures/Animation
Audio/Video
Client(web browsers) initiated
Platform independence
Web Server
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Answer HTTP requests
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Listens on TCP port 80
Support Services
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Secure HTTP
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Secure Socket Layer protocol
Listens on TCP port 443
FTP
URL
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Protocol or application
Hostname
TCP/IP port
Directory
Filename
URL Examples
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https://my.umbc.edu/fcgi-bin/myumbc.fcgi
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http://sunserver1.cs.umbc.edu:8080/
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telnet://spot.acme.com
CGI Scripting
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What’s CGI?
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Common Gateway Interface
Dynamically generate content
Usually Perl/C programs
Security Concern
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CGI scripts have access to files, network
connections, and other methods of moving data
Anyone can run a program on HTTP server
HTTP Server Installation
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Why Apache HTTP server?
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A powerful, flexible, HTTP/1.1 compliant
web server
Support OS: Unix, Linux, Windows NT/9x,
Netware 5.x, OS/2, and etc.
Open source
Highly configurable and extensible with
third-party modules
Configuring Apache
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Configuration files in the conf directory
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httpd.conf
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srm.conf
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TCP port
Location of log files and document files
Network and performance parameters
Virtual hosts
Controls server access resources
DocumentRoot Definition
access.conf
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Controls access on a per-file or per-directory basis
Running Apache
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Httpd daemon
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Start by hand
Start from rc scripts
Virtual Interfaces
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Why virtual interfaces?
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Host multiple websites on a single server
Configuring
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Create the virtual interface at the TCP/IP level
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Interface:instance, for example, eth0:1
Use ifconfig command
/etc/sysconfig/network-scripts make it permanent
Tell Apache about a virtual interface
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Add VirtualHost clauses in the http.conf file
Caching and Proxy Servers
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Why proxy?
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Exponentially growing information on Internet
Use replication on a national, regional or site level
Squid Internet Object Cache
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http://www.squid-cache.org/
Support HTTP FTP, gopher, and SSL
reduce access time as well as bandwidth
consumption
Setting up Squid
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Most important resource is physical memory,
RAM and disk space
Compile
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% tar xzf squid-2.0.RELEASE-src.tar.gz
% cd squid-2.0.RELEASE
% ./configure
% make
Install
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% make install
edit and customize the squid.conf file
Setting up Squid(cont)
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Start
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create the swap directories
% /usr/local/squid/bin/squid –z
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Start Squid by command
% /usr/local/squid/bin/squid (Squid 2.X)
% /usr/local/squid/bin/RunCache (Squid 1.1.X)
Anonymous FTP Server Setup
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Why FTP?
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Distributes software, document drafts and the like
Allows users to inspect the properties of files
Anonymous FTP
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FTP daemon: ftpd
Managed by inetd
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/etc/inetd.cof
/etc/services
Installed and turned on by default in Red Hat
Usernet News
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What’s usenet?
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the set of machines that exchange articles tagged
with one or more universally-recognized labels,
called newsgroups
Delivery method: flood fill
Usenet news feeds
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Retain the services of a company that specializes
in hosting Usenet
Get a “pull” feed from upstream service provider
Receive a normal feed that includes the article
headers but not the bodies. The article is pulled
only when a user asks to.