Chapter 22 Web Hosting and Internet Servers Xuanxuan Su

Topics Web FTP News

Web Hosting Web hosting platform Reliability Maintainability Security Performance Unix vs. Windows

HTTP protocol The foundation of the WWW TCP-based protocol Transmit documents Text Pictures/Animation Audio/Video Client(web browsers) initiated Platform independence

Web Server Answer HTTP requests Listens on TCP port 80 Support Services Secure HTTP Secure Socket Layer protocol Listens on TCP port 443 FTP

URL Protocol or application Hostname TCP/IP port Directory Filename

URL Examples telnet://spot.acme.com

CGI Scripting What’s CGI? Common Gateway Interface Dynamically generate content Usually Perl/C programs Security Concern 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 Why Apache HTTP server? 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 Configuration files in the conf directory httpd.conf TCP port Location of log files and document files Network and performance parameters Virtual hosts srm.conf Controls server access resources DocumentRoot Definition access.conf Controls access on a per-file or per-directory basis

Running Apache Httpd daemon Start by hand Start from rc scripts

Virtual Interfaces Why virtual interfaces? Host multiple websites on a single server Configuring Create the virtual interface at the TCP/IP level Interface:instance, for example, eth0:1 Use ifconfig command /etc/sysconfig/network-scripts make it permanent Tell Apache about a virtual interface VirtualHos Add VirtualHost clauses in the http.conf file

Caching and Proxy Servers Why proxy? Exponentially growing information on Internet Use replication on a national, regional or site level Squid Internet Object Cache Support HTTP FTP, gopher, and SSL reduce access time as well as bandwidth consumption

Setting up Squid Most important resource is physical memory, RAM and disk space Compile % tar xzf squid-2.0.RELEASE-src.tar.gz % cd squid-2.0.RELEASE %./configure % make Install % make install edit and customize the squid.conf file

Setting up Squid(cont) Start create the swap directories % /usr/local/squid/bin/squid –z 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 Why FTP? Distributes software, document drafts and the like Allows users to inspect the properties of files Anonymous FTP FTP daemon: ftpd Managed by inetd /etc/inetd.cof /etc/services Installed and turned on by default in Red Hat

Usernet News What’s usenet? the set of machines that exchange articles tagged with one or more universally-recognized labels, called newsgroups Delivery method: flood fill Usenet news feeds 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.