Web Server (Apache)

1. What is Web  server  and  explain  it?
A Web server is a system that delivers content or services to end users over the Internet. A Web          server consists of a physical server, server operating system (OS) and software used to facilitate          HTTP communication.

A computer that runs a Web site. Using the HTTP protocol, the Web server delivers Web pages            to browsers as well as other data files to Web-based applications.
       The Web server includes the hardware, operating system, Web server software, TCP/IP protocols         and site content (Web pages, images and other files). If the Web server is used internally and is         not exposed to the public, it is an "intranet server"  and if the Web server is used in the internet           and is exposed to the public, it is an Internet server.

2. What is Protocol?
A uniform set of rules that enable two devices to connect and transmit the data to one another.            Protocols determine how data are transmitted between computing devices  and  over networks.            They define issues such as error control  and  data compression methods. The protocol                        determines the following type of error checking to be used, data compression method  (if any),            how the sending device will indicate that it has finished a message and how the receiving device          will indicate that it has received the message.
         Internet protocols include TCP/IP (Transmission Control  Protocol / Internet  Protocol),
                                                   HTTP (Hyper  Text  Transfer  Protocol), 
                                                   FTP (File Transfer  Protocol)  and 
                                                   SMTP (Simple  Mail  Transfer  Protocol).

3. How  a  Web server works?
(i) If the user types an  URL  in his browsers address bar, the browser will splits  that  URL                      into a number of separate parts  including  address,  path name  and  protocol.
(ii) A  DNS  (Domain  Naming  Server) translates the domain name the user has entered into                      its  IP address,  a numeric combination that represents the site's  true address on the                              internet.
(iii) The browser now determines which protocol  (rules and regulation which the client                              machine used to communicate with servers)  should be used.  For example  FTP (File                          Transfer Protocol)  and  HTTP (Hyper Text  Transfer Protocol).
(iv)  The server sends  a  GET  request to the Web Server to retrieve the address it has been                          given.  For example when a user types  http://www.example.com/Myphoto.jpg ,  the                            browser sends  a  GET Myphoto.jpg command to example.com  server  and  waits for a                        response.  The server now responds to the browser's requests.  It verifies that the given                        address exist,  finds the necessary files,  runs the appropriate scripts,exchanges  cookies if                    necessary  and  returns the results back to the browser. If it cannot locate the file,  the server sends an error message to the client.
(v) Then the browser translates the data it has been given into  HTML  and  displays the                            results  to the user.

4. In how many ways can we host the websites?
IP based Web Hosting :
IP based web hosting is usedIP address  or  hostname web hosting.
Name based Web Hosting :
Hosting the multiple websites using single  IP address.
Port based Web Hosting :
Web hosting using another port number  ie., other than the default port number.
User based Web Hosting :
We can host the Web sites using the user name  and  password.

5. What is Apache Web Server?
Apache is a open source web server.  It is mostly used web server in the internet. httpd  is the              deamon that speaks the http  or  https  protocols. It is a text based protocol for sending and                  receiving the objects over a network connection. The http protocol  is sent over the wired                    network in clear text using default port number 80/tcp. To protect the website we can use https            web server for data encryption.

6. What is the profile for  Web server?
Package        : httpd
script        : /etc/init.d/httpd
Deamon        : httpd
Configuration file  : /etc/httpd/conf/httpd.conf   (for  http)
       /etc/httpd/conf.d/ssl.conf   (for  https)
Document  Root : /var/www/html
Log  files         : /var/log/httpd/access_log
       /var/log/httpd/error_log
Port  Number        : 80/http  and  443/https
*   If we want to configure the httpd server,  we have to follow the  ISET  rules.  where
                              I -  Install,   
                              S - Start, 
                      E - Enable    and   
                              T - Test.
*   To access the websites using the  CLI mode  e-links,   curl  tools   are used  and  to access the                websites using the browser in  Linux Firefox  is used.

7. How to make the http web server available to the cleint?
(a) First  assign the static  IP address  and  hostname  to the server.
(b) Check whether the server package  by   # rpm   -qa    httpd*    command.
(c) If not installed,  install the web server package by   # yum  install  httpd*   -y    command.
(d) Start the web server  and  enable web server service at next boot.
# service  httpd  start (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd (to enable the service at next boot  in  RHEL - 7)
(e) Open the browser  and  access the web server document.
# firefox  (to open the  firefox  browser)
*   Then  in address  bar type as  http://localhost/manual   and  press  Enter key.

8. How to configure the IP based virtual host Web server?
(a) First  assign the static  IP address  and  hostname  to the server.
(b) Check whether the server package  by 
                # rpm   -qa    httpd*    command.
(c) If not installed,  install the web server package by 
                # yum  install  httpd*   -y    command.
(d) Check the configuration file to configure the http web server by 
                # rpm   -qac   httpd    command.
(e) If required open the web server document  by 
                # rpm   -qad   httpd   command.
(f) Go to the configuration file directory  by 
                 # cd   /etc/httpd/conf.d
(g) Create the configuration for  IP based hosting.
# vim   /etc/httpd/conf.d/ip.conf
<VirtualHost    <IP address of the web server> : 80>
ServerAdmin   root@<hostname of the web server>
ServerName    <hostname of the web server>
DocumentRoot    /var/www/html
</VirtualHost>

<Directory    "/var/www/html">
AllowOverride   none
Require  All  Granted
</Directory> (save  and  exit  this  file)
Example :
# vim   /etc/httpd/conf.d/ip.conf       (create the configuration file)
<VirtualHost    172.25.9.11:80>
ServerAdmin root@server9.example.com
ServerName server9.example.com
DocumentRoot    /var/www/html
</VirtualHost>

<Directory    "/var/www/html">
AllowOverride  none
Require  All  Granted
</Directory>
(h) Go to document root directory  and  create the index.html  file.
# cd   /var/www/html
# vim   index.html
<html>
<H1>
This is IP based Web Hosting
</H1>
</html> (save  and  exit  this  file)
(i) Restart the web server deamon.
# service  httpd  start      (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on      (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd      (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd      (to enable the service at next boot  in  RHEL - 7)
(j) Add the service to the IP tables  and  firewall.
In  RHEL - 6 :
# iptables    -A   INPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# iptables    -A   OUTPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# service  iptables  save
# service  iptables  restart
In  RHEL - 7 :
# firewall-cmd    --permanent    --add-service=http
# firewall-cmd    --complete-reload
(k) Go to client system,  open the  firefox  browser  and  type as  http://server9.example.com                       in address bar and check the index page is displayed  or  not.
(l) We can also access the website using  elinks  CLI tool.
# yum  install  elinks*   -y (install the elinks  package)
# elinks    --dump   server9.example.com (access the index page)

9. How to configure the name based  web hosting?
(a) Make a directory for virtual  or  named based hosting.
# mkdir   /var/www/virtual
(b) Go to the configuration file directory  by 
               # cd   /etc/httpd/conf.d
(c) Create the configuration for  name based hosting.
# vim   /etc/httpd/conf.d/virtual.conf
<VirtualHost    <IP address of the web server> : 80>
ServerAdmin   root@<hostname of the web server>
ServerName    <virtual hostname of the web server>
DocumentRoot    /var/www/virtual
</VirtualHost>

<Directory    "/var/www/virtual">
AllowOverride   none
Require  All  Granted
</Directory> (save  and  exit  this  file)
Example :
# vim   /etc/httpd/conf.d/virtual.conf (create the configuration file)
<VirtualHost    172.25.9.11:80>
ServerAdmin root@server9.example.com
ServerName www9.example.com
DocumentRoot    /var/www/virtual
</VirtualHost>

<Directory    "/var/www/virtual">
AllowOverride  none
Require  All  Granted
</Directory>
(d) Go to named based virtual directory  and  create the index.html  file.
# cd   /var/www/virtual
# vim   index.html
<html>
<H1>
This is Name based Web Hosting
</H1>
</html> (save  and  exit  this  file)
(e) Restart the web server deamon.
# service  httpd  start (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on         (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd         (to enable the service at next boot  in  RHEL - 7)
(f) Add the service to the IP tables  and  firewall.
In  RHEL - 6 :
# iptables    -A   INPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# iptables    -A   OUTPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# service  iptables  save
# service  iptables  restart
In  RHEL - 7 :
# firewall-cmd    --permanent    --add-service=http
# firewall-cmd    --complete-reload                                                                                                               
(g) Go to client system,  open the  firefox  browser  and  type as  http://www9.example.com  in                   address bar and check the index page is displayed  or  not.
(h) We can also access the website using  elinks  CLI tool.
# yum  install  elinks*   -y (install the elinks  package)
# elinks    --dump   www9.example.com (access the index page)

10. How to configure the port based web hosting?
(a) Make a directory for port based hosting.
# mkdir   /var/www/port
(b) Go to the configuration file directory  by 
                # cd   /etc/httpd/conf.d
(c) Create the configuration for  port based hosting.
# vim   /etc/httpd/conf.d/port.conf
<VirtualHost    <IP address of the web server> : 8999>
ServerAdmin   root@<hostname of the web server>
ServerName    <port based hostname of the web server>
DocumentRoot    /var/www/port
</VirtualHost>

<Directory    "/var/www/port">
AllowOverride   none
Require  All  Granted
</Directory> (save  and  exit  this  file)
Example :
# vim   /etc/httpd/conf.d/virtual.conf  (create the configuration file)
<VirtualHost    172.25.9.11:8999>
ServerAdmin root@server9.example.com
ServerName port9.example.com
DocumentRoot    /var/www/port
</VirtualHost>

<Directory    "/var/www/port">
AllowOverride  none
Require  All  Granted
</Directory>
(d) Go to port based virtual directory  and  create the index.html  file.
# cd   /var/www/port
# vim   index.html
<html>
<H1>
This is Port  based Web Hosting
</H1>
</html> (save  and  exit  this  file)
(e) Generally port based web hosting requires  DNS  server.  So, we can solve this problem by                  the following way.
For that open the   /etc/hosts  file  enter the server name  and  IP addresses  on both                              server  and  client.
# vim   /etc/hosts
172.25.9.11 port5.example.com (save  and  exit  this  file)
(f) By default the web server runs on port number  80.  If we want to configure on deferent                      port number,  we have to add the port number in the main configuration file.
# vim   /etc/httpd/conf/httpd.conf
*   Go to  Listen : 80  line  and  open new line below this line  and  type as,
Listen : 8999 (save  and  exit  this  file)
(g) By default SELinux will allow 80 and  8080 port numbers only for webserver.  If we use                      different port numbers other than 80 or 8080 then execute the following command.
# semanage   port   -a   -t   http_port_t   -p   tcp   8999
(h) Restart the web server deamon.
# service  httpd  start  (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on  (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd  (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd  (to enable the service at next boot  in  RHEL - 7)
(i) Add the service to the IP tables  and  firewall.
In  RHEL - 6 :
# iptables    -A   INPUT   -i   eth0   -p   tcp   -m   tcp   --deport    8999  -j    ACCEPT
# iptables    -A   OUTPUT   -i   eth0   -p   tcp   -m   tcp   --deport    8999  -j    ACCEPT
# service  iptables  save
# service  iptables  restart
In  RHEL - 7 :
# firewall-cmd    --permanent    --add-service=http
# firewall-cmd    --permanent    -add-port=8999/tcp
# firewall-cmd    --complete-reload                                                                                                               
(j) Go to client system,  open the  firefox  browser  and  type as  http://port9.example.com  in                    address bar and check the index page is displayed  or  not.
(k) We can also access the website using  elinks  CLI tool.
# yum  install  elinks*   -y (install the elinks  package)
# elinks    --dump   port9.example.com (access the index page)

11. How to configure user authentication based web hosting?
It will ask user name  and  password to access this website.  So, we have to provide  http                       password.
(f) Go to the configuration file directory  by   # cd   /etc/httpd/conf.d
(g) Create the configuration for  user authentication based hosting.
# vim   /etc/httpd/conf.d/userbase.conf
<VirtualHost    <IP address of the web server> : 80>
ServerAdmin   root@<hostname of the web server>
ServerName    <hostname of the web server>
DocumentRoot    /var/www/html
</VirtualHost>

<Directory    "/var/www/html">
AllowOverride   none
Require  All  Granted
AuthType   Basic
AuthName    "This  site  is  protected"
AuthUserFile    /etc/httpd/pass
Require User    <user name>
</Directory> (save  and  exit  this  file)
Example :
# vim   /etc/httpd/conf.d/userbase.conf       (create the configuration file)
<VirtualHost    172.25.9.11:80>
ServerAdmin root@server9.example.com
ServerName server9.example.com
DocumentRoot    /var/www/html
</VirtualHost>

<Directory    "/var/www/html">
AllowOverride  none
Require  All  Granted
AuthType   Basic
AuthName    "This  site  is  protected"
AuthUserFile    /etc/httpd/pass
Require User    raju
</Directory>
(h) Go to document root directory  and  create the index.html  file.
# cd   /var/www/html
# vim   index.html
<html>
<H1>
This is User  Authentication  based Web Hosting
</H1>
</html> (save  and  exit  this  file)
(i) Restart the web server deamon.
# service  httpd  start (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on         (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd         (to enable the service at next boot  in  RHEL - 7)
(j) Add the service to the IP tables  and  firewall.
In  RHEL - 6 :
# iptables    -A   INPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# iptables    -A   OUTPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# service  iptables  save
# service  iptables  restart
In  RHEL - 7 :
# firewall-cmd    --permanent    --add-service=http
# firewall-cmd    --complete-reload     
(k) Create the user  and  assign the http  password.
# useradd  raju
*   Don't  give the normal password because this user requires the http password.
# htpasswd    -c m   /etc/httpd/pass   <user name>
Example :   # htpasswd    -c m   /etc/httpd/pass     raju
(l) Go to client system,  open the  firefox  browser  and  type as  http://server9.example.com                      in address bar and check the index page is displayed  or  not.  Then it asks password, so                      we have to provide http password.
(m)We can also access the website using  elinks  CLI tool.
# yum  install  elinks*   -y (install the elinks  package)
# elinks    --dump   server9.example.com (access the index page)
*   Then it asks password, so we have to provide http password.

12. How to restrict the web sites access from  hosts  or  domains  or  networks?
(a) Go to the configuration file directory  by   # cd   /etc/httpd/conf.d
(b) Create the configuration for  IP based hosting.
# vim   /etc/httpd/conf.d/restrict.conf
<VirtualHost    172.25.9.11:80>
ServerAdmin   root@server9.example.com
ServerName    server9.example.com
DocumentRoot    /var/www/html
</VirtualHost>

<Directory    "/var/www/html">
AllowOverride   none
Require  All  Granted
Order  Allow,  Deny
Allow  from   172.25.9.0  or  172.25.0   (allows  172.25.9  network  or  172.25 network to                    access the websites)
Deny from .my133t.org(deny the systems of *.my133t.org domain to access the websites)
</Directory>

13. How to Redirect the website?
*   Redirecting means whenever we access the website,  it redirects to another website.
(a) Go to the configuration file directory  by   # cd   /etc/httpd/conf.d
(b) Create the configuration for  redirect based hosting.
# vim   /etc/httpd/conf.d/rediect.conf
<VirtualHost    172.25.9.11:80>
ServerAdmin   root@server9.example.com
ServerName    server9.example.com
DocumentRoot    /var/www/html
Redirect   /   "http://www.google.com"
</VirtualHost>

<Directory    "/var/www/html">
AllowOverride   none
Require  All  Granted
</Directory> (save  and  exit  this  file)
(c) Go to document root directory  and  create the index.html  file.
# cd   /var/www/html

# vim   index.html
<html>
<H1>
This is Redirect based Web Hosting
</H1>
</html> (save  and  exit  this  file)
(d) Restart the web server deamon.
# service  httpd  start (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd (to enable the service at next boot  in  RHEL - 7)
(e) Add the service to the IP tables  and  firewall.
In  RHEL - 6 :
# iptables    -A   INPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# iptables    -A   OUTPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# service  iptables  save
# service  iptables  restart
In  RHEL - 7 :
# firewall-cmd    --permanent    --add-service=http
# firewall-cmd    --complete-reload                                                                                                               
(f) Go to client system,  open the  firefox  browser  and  type as  http://server9.example.com                      in address bar and check the redirection  google web page is displayed  or  not.
(g) We can also access the website using  elinks  CLI tool.
# yum  install  elinks*   -y (install the elinks  package)
# elinks    --dump   server9.example.com (access the index page)
*   This website redirects to the google website.

14. How to configure the website with alias name?
(a) Go to the configuration file directory  by   # cd   /etc/httpd/conf.d
(b) Create the configuration for  alias based hosting.
# vim   /etc/httpd/conf.d/alias.conf
<VirtualHost    172.25.9.11:80>
ServerAdmin   root@server9.example.com
ServerName    server9.example.com
DocumentRoot    /var/www/html
Alias   /private    /var/www/html/private
</VirtualHost>

<Directory    "/var/www/html/private">
AllowOverride   none
Require  All  Granted
</Directory> (save  and  exit  this  file)
(c) Create  private  directory in  /var/www/html.
# mkdir    /var/www/html/private
(c) Go to document root private directory  and  create the index.html  file.
# cd   /var/www/html/private
# vim   index.html
<html>
<H1>
This is Alias based  Web Hosting
</H1>
</html> (save  and  exit  this  file)
(d) Restart the web server deamon.
# service  httpd  start (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd (to enable the service at next boot  in  RHEL - 7)
(e) Add the service to the IP tables  and  firewall.
In  RHEL - 6 :
# iptables    -A   INPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# iptables    -A   OUTPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# service  iptables  save
# service  iptables  restart
In  RHEL - 7 :
# firewall-cmd    --permanent    --add-service=http
# firewall-cmd    --complete-reload                                                                                                               
(f) Go to client system,  open the  firefox  browser  and  type as                                                                  http://server9.example.com/privae  in address bar  and  check the private  or  alias                          based web page is displayed  or  not.
(g) We can also access the website using  elinks  CLI tool.
# yum  install  elinks*   -y (install the elinks  package)
# elinks    --dump   server9.example.com/private (access the index page)
15. How to configure the directory based web hosting?
(a) Go to the configuration file directory  by   # cd   /etc/httpd/conf.d
(b) Create the configuration for  direct based hosting.
# vim   /etc/httpd/conf.d/confidential.conf
<VirtualHost    172.25.9.11:80>
ServerAdmin   root@server9.example.com
ServerName    server9.example.com
DocumentRoot    /var/www/html
</VirtualHost>

<Directory    "/var/www/html/confidential">
AllowOverride   none
Require  All  Granted
</Directory> (save  and  exit  this  file)
(c) Create  confidentialdirectory in  /var/www/html.
# mkdir    /var/www/html/confidential
(c) Go to confidential directory  and  create the index.html  file.
# cd   /var/www/html/confidential
# vim   index.html
<html>
<H1>
This is Alias based  Web Hosting
</H1>
</html> (save  and  exit  this  file)
(d) Restart the web server deamon.
# service  httpd  start (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on         (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd         (to enable the service at next boot  in  RHEL - 7)
(e) Add the service to the IP tables  and  firewall.
In  RHEL - 6 :
# iptables    -A   INPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# iptables    -A   OUTPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# service  iptables  save
# service  iptables  restart
In  RHEL - 7 :
# firewall-cmd    --permanent    --add-service=http
# firewall-cmd    --complete-reload                                                                                                               
(f) Go to client system,  open the  firefox  browser  and  type as                                                                  http://server9.example.com/confidential in address bar  and  check the directory based                      web page is displayed  or  not.
(g) We can also access the website using  elinks  CLI tool.
# yum  install  elinks*   -y (install the elinks  package)
# elinks    --dump   server9.example.com/confidential (access the index page)
16. How to configure the web server to display the user defined home page not the index.html page?
Normally Apache will look the index.html  as the home page by default.  If the name changed it          will display the home page without configure that one. For that we can do the above as follows.
(i) Go to configuration file directory by   # cd   /etc/httpd/conf.d   command.
(ii) Create a userpage configuration file.
# vim    userpage.conf
<VirtualHost     172.25.9.11:80>
ServerAdmin    root@server9.example.com
ServerName    server9.example.com
DocumentRoot    /var/www/html
DirectoryIndex    userpage.html
</VirtualHost>

<Directory    "/var/www/html">
AllowOverride  none
Require   All   Granted
</Directory>      (save  and  exit  this  file)
(iii) Go to document root directory by   # cd   /var/www/html    command.
(iv) # vim   userpage.html
<html>
<H1>
This is userpage as home page web hosting
</H1>
</html>      (save  and  exit  this  file)
(d) Restart the web server deamon.
# service  httpd  start  (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on          (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd          (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd  (to enable the service at next boot  in  RHEL - 7)
(e) Add the service to the IP tables  and  firewall.
In  RHEL - 6 :
# iptables    -A   INPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# iptables    -A   OUTPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# service  iptables  save
# service  iptables  restart
In  RHEL - 7 :
# firewall-cmd    --permanent    --add-service=http
# firewall-cmd    --complete-reload                                                                                                               
(f) Go to client system,  open the  firefox  browser  and  type as  http://server9.example.com                       in address bar and  check the  user defined  web page is displayed  or  not.
(g) We can also access the website using  elinks  CLI tool.
# yum  install  elinks*   -y (install the elinks  package)
# elinks    --dump   server9.example.com (access the index page)

17. How to configure  CGI  based web hosting?
CGI  content will change dynamically every time the client accessed it. Normal web server will          not be used to support this type of web hosting. To access these dynamic pages,  we have to                configure the web server as  ".wsgi"  server. The following steps will configure the  CGI  web              server.
(a) Install the  CGI  package by   # yum  install  mod_wsgi*    -y   command.
(b) Download  or  create the  CGI  script file in  web server's  document root directory.
Example :   # cp   webapp.wsgi      /var/www/html
(c) Create  the configuration file for  CGI  based web hosting.
<VirtualHost    172.25.9.11:80>
ServerAdmin    root@server9.example.com
ServerName    webapp9.example.com
DocumentRoot    /var/www/html
WSGIScriptAlias     /     /var/www/html/webapp.wsgi
</VirtualHost>
(d) Restart the web server deamon.
# service  httpd  start (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd (to enable the service at next boot  in  RHEL - 7)
(e) Add the service to the IP tables  and  firewall.
In  RHEL - 6 :
# iptables    -A   INPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# iptables    -A   OUTPUT   -i   eth0   -p   tcp   -m   tcp   --deport    80  -j    ACCEPT
# service  iptables  save
# service  iptables  restart
In  RHEL - 7 :
# firewall-cmd    --permanent    --add-service=http
# firewall-cmd    --complete-reload                                                                                                               
(f) Go to client system,  open the  firefox  browser  and  type as  http://webapp9.example.com                  in address bar and  check the  CGI  based web page is displayed  or  not.
(g) We can also access the website using  elinks  CLI tool.
# yum  install  elinks*   -y (install the elinks  package)
# elinks    --dump   webapp9.example.com (access the index page)

18. What is secured web server?
Secured web server means  normal  Apache web server with  SSL  support.  In normal web                  server the data communication is done in plain text format.  So,  there is no security for data                because everyone can access the data. If we want to provide security to the data, then we have            to configure the web server with  SSL support. 

19. What is the profile of secured web server?
Package         : mod_ssl
Configuration file : /etc/httpd/conf.d/ssl.conf
Private key location : /etc/pki/tls/private
Public key location : /etc/pki/tls/certs
Authentication certificate : /etc/pki/tls/certs
Port  number : 443
*   Private key extention is   " . key "    and    public key extention is   " . crt "

20. How to configure the secured web server?
(a) Install  the web server  and  secure shell packages.
# yum  install  httpd*   mod_ssl*    -y   command.
(b) Download the private key  and  public certificates.
# cd   /etc/pki/tls/private
# wget   http://classroom.example.com/pub/tls/private/server<no.> . key
# cd   /etc/pki/tls/certs
# wget   http://classroom.example.com/pub/tls/certs/server<no.> . crt
# wget   http://classroom.example.com/pub/example-ca.crt
(c) Create the configuration file for secured web server.
# vim  /etc/httpd/conf.d/https.conf
<VirtualHost    172.25.9.11:443>
ServerAdmin    root@server9.example.com
ServerName    server9.example.com
DocumentRoot    /var/www/html
</VirtualHost>
(d) We have to copy  7 lines  from  ssl.conf  file  to  https.conf  file.
# vim   -O   ssl.conf   https.conf
Copy  the line numbers   70,  75,  80,  93,  100,  107,   116  copy   and  paste them in                            https.conf   file.
So,  after copied those line the https.conf   file should be as below.
<VirtualHost    172.25.9.11:443>
ServerAdmin    root@server9.example.com
ServerName    server9.example.com
SSLEngine on
SSLProtocol all -SSLv2   -SSLv3
SSLCipherSuite ALL:!ADH:!EXPORT:!SSLv2:RC4+RSA:+HIGH:+MEDIUM:+LOW
SSLCertificateFile /etc/pki/tls/certs/server9.crt
SSLCertificateKeyFile /etc/pki/tls/private/server9.key
#SSLCertificateChainFile /etc/pki/tls/certs/example-ca.crt
DocumentRoot    /var/www/html
</VirtualHost>
<Directory     "/var/www/html">
AllowOverride 
Require   All   Granted
</Directory>      (save  and  exit  this  file)
(e) Go to document root directory by   # cd   /var/www/html    command.
(f) # vim   index.html
<html>
<H1>
This is a  secured  web hosting
</H1>
</html>      (save  and  exit  this  file)
(g) Restart the web server deamon.
# service  httpd  start (to start the webserver  deamon  in  RHEL - 6)
# chkconfig  httpd  on (to enable the service at next boot  in  RHEL - 6)
# systemctl  restart  httpd (to start the webserver  deamon  in  RHEL - 7)
# systemctl  enable  httpd (to enable the service at next boot  in  RHEL - 7)
(h) Add the service to the IP tables  and  firewall.
In  RHEL - 6 :
# iptables    -A   INPUT   -i   eth0   -p   tcp   -m   tcp   --deport    443  -j    ACCEPT
# iptables    -A   OUTPUT   -i   eth0   -p   tcp   -m   tcp   --deport    443  -j    ACCEPT
# service  iptables  save
# service  iptables  restart
In  RHEL - 7 :
# firewall-cmd    --permanent    --add-service=http
# firewall-cmd    --permanent    --add-service=https
# firewall-cmd    --complete-reload                                                                                                               
(i) Go to client system,  open the  firefox  browser  and  type as  https://server9.example.com/   in address bar  and  check the  secured  web page is displayed  or  not.
21. How to generate our own private  and  public keys using  crypto-utils  package?
(i) Install the package by   # yum  install  crypto-utils*   -y    command.
(ii) Create our own public  and  private keys by   # genkey    <hostname  of  the  server>                            command.
Example : 
          #genkey  server9.example.com  (one window will be opened  and  we have to enter the details)
    Click on  Next   ---> Don't change the default size  --->  Next  --->  No  --->The keys are                       generated  their directories.
     Other  useful  commands :
      # httpd    -t (to check the web server configuration file for  syntax  errors)