apache web server setup 3

Web Technology – Web Server Setup : Chris Uriarte

Meeting 3: Advanced Apache Topics

Rutgers University Internet Institute

Instructor: Chris Uriarte(non IPVH exc)


Virtual Hosting

• General term used when you run more than one website on a single system.

• Allows ISPs and hosting providers to make money by sharing resources among clients. Allows companies and individuals to save time and money - a single machine can host many websites.


Options for Hosting More than One Website on a Single System

• Run separate instances of httpd servers: httpd –f /usr/local/apache/conf/httpd-virtual.conf

• Run a server that will listen on multiple ports and serve different content depending on the port.

• True Virtual Hosting - Allows multiple IP address and/or host names to be served through a single Apache server. – IP-Based – Name-Based (not supported by very early Web

browsers…Netscape 2.0/IE 3.0)


Virtual Hosting: IP Based • You must configure your machine to

“listen” for multiple IP addresses. One NIC binds to multiple IP addresses

• One hostname is associated with each IP address

www.yahoo.com

sports.yahoo.com

216.32.74.52

216.115.105.243

SERVER

NIC


Virtual Hosting: Name Based

• A machine can host multiple websites using only 1 IP address

• All hostnames have the same IP address

• Becoming more and more popular.

some.mydomain.com

www.hisdomain.com

165.145.26.110

SERVER

NIC


Setting-Up IP-Based Virtual Hosting: An Overview

• Once you have secured the domain names/hostnames you want to use for your website, you need to assign each of them a unique IP address.

• Some ISPs can assign you additional IP addresses.

• Blocks of IP addresses are usually assigned with business T1s or DSL lines.


Setting-Up IP-Based Virtual Hosting, Con’t.

• You need to have DNS properly configured for your domains, e.g. The world needs to know that www.yourdomain.com is at the IP address 123.23.34.56.

• Remember, your ISP can usually provide DNS service for your domains.


IP-Based Virtual Hosting: Setting Up Your Machine

• Your web server needs to be configured to listen for the IP addresses related to your websites:

• UNIX-based OSs allow you to configure multiple IP addresses using the ifconfig command (must be run as root)

• Usage: ifconfig interface:<sub-number> IP– e.g: ifconfig eth0:0 165.230.30.71 – ifconfig eth0:1 165.230.30.72

• WinNT IP setup through Network control panel.


Configuring Apache for IP-Based Virtual Hosting

• Configuring Apache for Virtual Hosting is quite simple: Simply add a <VirtualHost> block within the httpd.conf file.

• Format:<VirtualHost IP-or-HOSTNAME:Port> #Any Valid httpd.conf directives</VirtualHost>

• Required for each Virtual Host website your are using…therefore your httpd.conf can have multiple <VirtualHost> blocks.


IP-Based VH Configuration con’t.• Typical <VirtualHost> block in httpd.conf:<VirtualHost www.bearsnest.org>

DocumentRoot /home/www/bearsnest/htdocsServerAdmin [email protected] www.bearsnest.orgErrorLog logs/bears-error_logTransferLog logs/bears-access_logRedirect /adprotech http://www.adprotech.comAlias /staff /home/staff/chrisjur/htdocs/bn/staff

</VirtualHost>

• The key: Vitual hosts will have their own unique DocumentRoot – different content for different sties.


Steps for Setting-Up Name-Based Virtual Hosting

• When setting up Name-based virtual hosts, you need to add the special NameVirtialHost Directive to your httpd.conf:– NameVirtualHost <Your IP Address>

• Which tells Apache the single IP address you will use for all your websites.

• Now simply add <VirtualHost> blocks for each of your website domains.


Name-Based VH ExamplesNameVirtualHost 165.230.30.68<VirtualHost www.yoursite.org>

DocumentRoot /home/www/yoursite/htdocsServerAdmin [email protected] www.yoursite.comErrorLog logs/yoursite-error_log

</VirtualHost><VirtualHost www.mysite.com>

DocumentRoot /home/www/mysite/htdocsServerAdmin [email protected] www.mysite.orgErrorLog logs/mysite-error_log

</VirtualHost>


Virtual Hosting Recap

• Get your DNS configured for each domain• IP-based Virtual Hosting vs. Name-based Virtual

Hosting• Configure your server for multiple IP addresses if

using IP-based Virtual Hosting• Create new directories for new Document Roots• Add <VirtualHost> blocks to your httpd.conf


Delivering Dynamic Content

• Two ways of delivering dynamic content for the Web: client-side or server-side technologies

• Client-Side – Elements are downloaded to the browser and execute

on the client’s system.

– Examples: JavaScript, Java Applets, client-side image maps.

– Web server administrator needs to see that MIME types are set correctly.


Dynamic Content, con’t.• Server-Side

– Server processes “on-the-fly” content that is passed to client browser.

– Examples: server-side includes, CGI (Common Gateway Interface), server-side image maps, ASP (Active Server Pages), Java Servlets. PHP

– Server-side technologies generally require additional configuration of the Web server in order to function properly. Usually require specific Apache modules.

– Enabling server-side technologies generally has security implications.


Server-Side Includes• Server-side includes are directives that can be

placed in HTML documents to execute other programs or to output data.

• Requires mod_include. • To enable SSI, make the following

modifications to httpd.conf: – Options Includes (or IncludesNOEXEC)

• The options directive only works within a specific Directory or VirtualHost container.


Enabling Server Side Includes, con’t…

• To tell Apache how to interpret SSI documents, add the following to httpd.conf: AddType text/html .shtml

AddHandler server-parsed .shtml

• These lines are usually commented out by default, so you just need to uncomment them.

• All files with indicated extension(s) will be parsed by Apache server prior to being transmitted to the client, e.g. web page files that end with .shtml can contain SSI’s.

Server-Side Includes Examples

• The general form of the SSI directive is:  For example:

<!—include file=“include.html”-->

Will insert the contents of the file file “include.html” when displayed in the client’s browser.

<!—echo var=“LAST_MODIFIED”-->

Prints the last time your HTML file was modified.


Server Side Includes, con’t.

• The Server Side Include in the .html file is evaluated by Apache and the output is displayed to the client.

• Check out http://blender.rutgers.edu/~chrisjur/ssi.shtml for an example ( source file is /home/staff/chrisjur/public_html/ssi.shtml on blender.rutgers.edu server)


CGI

• CGI (Common Gateway Interface) is a protocol for getting, processing, and returning information through Web pages.

• CGI programs or scripts can be written in a variety of languages including Perl, Python, VB Script, JavaScript, and C.

• CGI scripts are generally triggered by data supplied by the client.


Enabling CGI• There are two ways to enable Apache to recognize

CGI scripts: – To allow CGI scripts in one system-wide directory outside of

the document root (All CGI programs must be placed in one directory): • ScriptAlias /cgi-bin “/home/students/<username>/apache/cgi-bin/”

– Within a container: • Options ExecCGI <other options> • SetHandler cgi-script

– To enable files with only specific extensions as CGI scripts use AddHandler instead of • SetHandler: AddHandler cgi-script .cgi


Enabling CGI: Example 1

• Sometimes it’s convenient to have one centrialized “cgi-bin” directory where all CGI programs are kept.

• You can access all the scripts through http://www.domain.com/cgi-bin/scriptname

• To do this at the following line to httpd.conf:ScriptAlias /cgi-bin

“/home/students/<username>/apache/cgi-bin/”


Enabling CGI: Example 2

• You can enable CGI scripts to be placed in any directory by specifying some CGI directives in a directory container within the httpd.conf or an .htaccess file. This allows CGI execution in the directory specified:

<Directory /home/user/htdocs>

Options ExecCGI (other options…)

SetHandler cgi-script

</Directory>


Limiting CGI Access

• If you do not have Options ExecCGI or a ScriptAlias directive, the execution of CGI programs will be denied.

• You can limit CGI access to only programs that end with a specific extension:– SetHandler: AddHandler cgi-script .cgi

(limits CGI execution to programs that only end in .cgi)


CGI: Examples

• http://blender.rutgers.edu/~chrisjur/cgi-bin/test.cgi - CGI script written in Perl, simply outputs current time and the end-user’s browser type (source at /home/staff/chrisjur/public_html/cgi-bin/test.cgi)

• http://blender.rutgers.edu/~chrisjur/cgi-bin/shell.cgi - Written as a shell script in, prints current date/time and lists files in its directories (source at /home/staff/chrisjur/public_html/cgi-bin/shell.cgi)


More CGI Examples…

• http://blender.rutgers.edu/~chrisjur/feedback.html - More traditional example of what CGI is used for. An HTML form posts to a CGI script written in Perl (/home/staff/chrisjur/public_html/cgi-bin/feedback.cgi) which emails form contents to a recipient and performs some validation logic.


Exercise: Enabling CGI

• Enable CGI via the ScriptAlias directive in your httpd.conf. Specify a cgi-bin directory to place all your CGI scripts.

• Copy /home/staff/chrisjur/test.cgi script to your cgi-bin directory. Make the test.cgi script executeable (chmod a+x test.cgi)

• Access the script via http://blender.rutgers.edu:YourPort/cgi-bin/test.cgi

apache web server setup 3

Technology

domain ip

single ip address

blocks of ip addresses

unique ip address

additional ip addresses

ipbased vh configuration

virtual hosting recap

server nic